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Misfire, where do i go from here. by Dukesterpro
Started on: 02-09-2023 10:45 AM
Replies: 172 (2524 views)
Last post by: Dukesterpro on 05-02-2023 08:19 AM
Dukesterpro
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Report this Post02-17-2023 02:50 PM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 82-T/A [At Work]:
Is yours a 1984? I couldn't remember if you said this anywhere (didn't immediately see it above).

It appears as though the 1984 distributor is totally different than the 85-86 one. The condensor appears to be mounted internally, with a completely different style of ignition control module, rather than the newer style, which has it mounted externally. For some reason, I cannot find it anywhere, you don't seem to offer this piece separately. Unless I'm just completely wrong, but I unfortunately do not have my 1984 anymore to go out and compare.

Can you take a picture of the part you took off? Or are you saying it's missing completely?



I do have a 1984 and that little red piece up above is the piece.

Im starting to dig up old forum posts, It looks like I might be up a very specific creek without a paddle
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Report this Post02-17-2023 02:52 PM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post

Dukesterpro

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Yes it is a 1984,

I have uncovered some old forum posts and it appears I am up a specific creek without a paddle.

I literally just bought this 84 dizzy. I wonder what could be done now.
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Report this Post02-17-2023 03:51 PM Click Here to See the Profile for PhatMaxSend a Private Message to PhatMaxEdit/Delete MessageReply w/QuoteDirect Link to This Post
Do have any other angles of the part in the pic ?


 
quote
Originally posted by Dukesterpro:

Its in my trunk right now I will pull it out when i get home.


In the mean time, what is this thing. I thought it was a tach filter. But someone's telling me its not.



New distributors in, and here is where I am at.

* Still reverse high idling. No High Idle at cold, progressively faster with heat.
*Smooth Tach when cold and low rpm, gets bouncier with heat and revving about 3000
*Stumble when heavy load on engine. (Eg half throttle in 4th gear at 35mph).


Could this be a injector problem? Still looking for ideas. I am still looking for a scanner.



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Dukesterpro
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Report this Post02-17-2023 04:20 PM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by PhatMax:

Do have any other angles of the part in the pic ?




Just that, the sides of the cap were burst and leaking. That was the only label on it
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Report this Post02-17-2023 09:01 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dukesterpro:

I can't even Identify it by its part number, its like it doesn't exist. Not even in old (1985-86) components catalogs at work.


Because that's probably an aftermarket distributor... possibly by Cardone. It's been about 20 years since I looked on the inside of a 2.5 distributor, so I can't be 100% sure.

The reason I think it may be aftermarket... look at these 2.8 distributors. Factory on left, aftermarket on right.



[EDIT] It could be that unlike the 2.8's, the duke's distributors always had the later style. See below.

[This message has been edited by Patrick (edited 02-17-2023).]

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Report this Post02-17-2023 11:02 PM Click Here to See the Profile for 82-T/A [At Work]Send a Private Message to 82-T/A [At Work]Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dukesterpro:

Just that, the sides of the cap were burst and leaking. That was the only label on it



Ok, this definitely has to be your problem... the engine will definitely run like crap with this messed up... because it literally cannot handle timing adjustments.

They do sell remanufactured distributors, with the new condensors in them. Check Rock Auto... I also saw some on Summit Racing when I was searching for a picture of it for you.
Patrick, the picture you're posting is the difference between the old style and the new style of distributor. I wouldn't say the new one is "aftermarket" per-se, but it's actually GM's replacement for that older style. They just realized that it was a better design, so they don't even rebuild those old ones like that anymore from what I understand... you have to really search for those old ones.
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Report this Post02-17-2023 11:15 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 82-T/A [At Work]:

Patrick, the picture you're posting is the difference between the old style and the new style of distributor. I wouldn't say the new one is "aftermarket" per-se, but it's actually GM's replacement for that older style.


So you're saying that when Pontiac was still around, that they would've have Delco Remy distributors on the shelf that looked like the style of the Cardone units?

[EDIT] Visions of the inside of my duke's distributor are beginning to creep back into my consciousness. It appears the guts look like what I thought were "aftermarket" distributors for the duke. Only one way for me to sort this out. If it's not raining tomorrow, I'll pull the distributor cap and rotor off the duke in my parts car and have a look under there!

[This message has been edited by Patrick (edited 02-17-2023).]

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Report this Post02-18-2023 10:34 PM Click Here to See the Profile for 82-T/A [At Work]Send a Private Message to 82-T/A [At Work]Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

So you're saying that when Pontiac was still around, that they would've have Delco Remy distributors on the shelf that looked like the style of the Cardone units?



Yeah, it wasn't just Cardone... pretty much all the distributor manufacturers went to this new design. The AC Delco replacement distributor had this new design as well. It was significantly improved over the older style that the Fiero originally came with. The shaft, base, etc... is all still the same, they just upgraded that one piece. You can still find rebuilt versions of the original if you really wanted it, but almost everyone, including AC Delco is using the newer pickup design.

This image is actually from my website: https://www.pontiacperforma...es/Dist_Upgrade.html

Of course, I stole that picture originally too, haha... but I used MS Paint back in like 2008 to put OLD and NEW on it.


EDIT: Yeah, here you go... this is a remanufactured one from AC Delco: https://www.rockauto.com/en...einfo.php?pk=3863712

[This message has been edited by 82-T/A [At Work] (edited 02-18-2023).]

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Patrick
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Report this Post02-19-2023 04:54 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 82-T/A [At Work]:

EDIT: Yeah, here you go... this is a remanufactured one from AC Delco


That's for a 2.8 V6. Find one for a duke.
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Report this Post02-19-2023 08:16 PM Click Here to See the Profile for 82-T/A [At Work]Send a Private Message to 82-T/A [At Work]Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

That's for a 2.8 V6. Find one for a duke.



Here you go, AC Delco, with the newer style of rotor: https://www.rockauto.com/en...einfo.php?pk=3863619




I only mentioned the V6 simply because you were bringing it up here:

 
quote
Originally posted by Patrick:

The reason I think it may be aftermarket... look at these 2.8 distributors. Factory on left, aftermarket on right.




This replacement from Rock Auto is $114, but it has everything, including the condenser. If he needs or is planning on getting a new one, you'll definitely want the newer style, it's significantly better than the older style with the tabs. Later GM-style distributors went with this style of pickup, and is why they switched.
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Report this Post02-19-2023 09:24 PM Click Here to See the Profile for zkhenningsSend a Private Message to zkhenningsEdit/Delete MessageReply w/QuoteDirect Link to This Post
Tach filter is on the white wire coming off the gray plug on the ignition coil for the duke. The other wire coming off the same plug is a thick red/pink wire. Both wires go to the C500 connector in the engine bay. The tach filter is a little metal cylinder that cleans up the signal from the coil. Square component that was messed up in your dist I believe is the pickup, so with that malfunctioning your ICM/ECU will not know where the timing actually is.

My wiring info is for an 85 2.5, but imagine they stuck with the same colors on the wires.

[This message has been edited by zkhennings (edited 02-19-2023).]

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Report this Post02-19-2023 09:36 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 82-T/A [At Work]:

... you'll definitely want the newer style, it's significantly better than the older style with the tabs. Later GM-style distributors went with this style of pickup, and is why they switched.


I guess what surprises me is that it appears (but not absolutely confirmed) that the '84 duke only ever came from the factory with the "newer" style distributor, whereas the later made '85-'88 2.8 only ever came from the factory with the "older" style distributor... which as pictured below is still available rebuilt.

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Dukesterpro
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Report this Post02-20-2023 02:08 AM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hello everyone,

I was away this weekend, part of the urgency to fix this car was a 400+ mile road trip that I had been planning to take in the Fiero. However, considering the fact that I am having consistent and worrying idle and misfire issues, I decided to do the sensible and mature thing and take the car anyways. I am happy to report that she did very well on her trip with no notable change in performance. As long as I stayed under the half pedal, she cruised at 85mph / 3000 rpm with no issues.

Here's a fun Fiero-themed tidbit from my trip. The instigator is the one on the ground. I haven't put it on a pike quite yet.



Anyways back to the topic at hand. Bouncy tach and mystery distributor. I am lucky to have a good relationship with the previous owner of the car and all of the paperwork for the absolute bare minimum amount of work that had been done on it by a dealer. He did all the other work himself. The distributor I pulled is the one that it was delivered to him with. Right from the factory. The replacement I bought from rock auto is visually identical to the original one. The only difference is that it does not have our red component, it expects you to move it over.. The old distributor is stamped Delco Remy. Patrick, does your distributor have anything wired in a similar location. If it does, maybe we can find out the specifications of what it is, and I can try to create a generic version of it.




Something of note. My car does not have an external silver tach filter can. According to the previous owner, it was never removed. He never did any ignition work to the car in the 40 years he owned it except for spark plugs and spark wires.

What do we think that red piece does? If not a tach filter what? Please refer to the little diagram I made to see how it was wired.

[This message has been edited by Dukesterpro (edited 02-20-2023).]

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Report this Post02-20-2023 12:24 PM Click Here to See the Profile for 82-T/A [At Work]Send a Private Message to 82-T/A [At Work]Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

I guess what surprises me is that it appears (but not absolutely confirmed) that the '84 duke only ever came from the factory with the "newer" style distributor, whereas the later made '85-'88 2.8 only ever came from the factory with the "older" style distributor... which as pictured below is still available rebuilt.




No, that's definitely not the case. I bought a 1984 Fiero 2m4 back in the day (mid 90s) that was 100% all original. I also had a 1985 Fiero 2m4 that I bought at auction that was also all original. I've probably futzed through at least ~100 Fieros in the junkyard, and I can pretty confidently say that all the Fieros that were sold, came with the original style of "pickup" rotor as you posted in that image. The newer one with the triangular points within the ring is definitely the newer style.

But it's worth mentioning that the 84 distributor is just different anyway from the 85+ models. The condensor (to answer dukesterpro) is internally mounted within the distributor in the 1984, where as the 1985+ had it mounted externally (from what I remember). In this case, he should just spend the $114 and get the new / rebuilt distributor that comes with everything already.

More on the 84/85 stuff, things were not so cut and dry in 1985, because many many thousands of 1985 Fieros were using parts from 1984s. The 1985 Fiero that I had was a very early-production 1985, and it still had flat-tappet lifters, and a bunch of other things that were 84-Specific (and the VIN matched)... where as they switched to roller-lifters. There were even some 85 Fieros that came with 84 Fiero harmonic balancers.


EDIT: But back on the distributors... to be perfectly clear... no Fiero ever "came from the factory" with the distributor that has the star of David pattern. They all came with the one that looks like little points sticking up. But the "star of David" design is a NEWER design. As I mentioned, if you really want the older style (originality, concourse restoration?)... you can still find them rebuilt. But almost everyone has gone to the newer style because it's better and less likely to foul.

[This message has been edited by 82-T/A [At Work] (edited 02-20-2023).]

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Dukesterpro
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Report this Post02-20-2023 01:06 PM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post
I already bought the new distributor. It didn't have the condenser.

Id have to rewire to use the later style distributor with the plugs on the outside right? Besides, it still doesn't change the fact that apparently this car needs that piece. Im lost as to what you guys think i should do here?
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Report this Post02-20-2023 01:13 PM Click Here to See the Profile for 82-T/A [At Work]Send a Private Message to 82-T/A [At Work]Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dukesterpro:

I already bought the new distributor. It didn't have the condenser.

Id have to rewire to use the later style distributor with the plugs on the outside right? Besides, it still doesn't change the fact that apparently this car needs that piece. Im lost as to what you guys think i should do here?



Honestly, it should have come with it, it's an integrated part of that distributor, and the one on rock auto when I looked showed it in there. My guess is someone bought it, "borrowed it" and then returned it, possibly. Either way, Call the Fiero Factory, or the Fiero Store... see if they have the piece that you need. Make sure you tell them you have a 1984... there were a lot of one-off things in 84, and early 1985.


Fiero Factory:
https://thefierofactory.com/

The Fiero Store:
https://www.fierostore.com/
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Report this Post02-20-2023 11:03 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dukesterpro:

Patrick, does your distributor have anything wired in a similar location. If it does, maybe we can find out the specifications of what it is, and I can try to create a generic version of it.


I've had a busy last couple of days. Hopefully tomorrow I can do some Fiero related stuff. I have two '84 Fieros here that I've owned for 20 years. As far as I know, they both have their original distributors. I'll do some digging and report back.
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Report this Post02-21-2023 10:10 AM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 82-T/A [At Work]:
Honestly, it should have come with it, it's an integrated part of that distributor, and the one on rock auto when I looked showed it in there. My guess is someone bought it, "borrowed it" and then returned it, possibly. Either way, Call the Fiero Factory, or the Fiero Store... see if they have the piece that you need. Make sure you tell them you have a 1984... there were a lot of one-off things in 84, and early 1985.


Fiero Factory:
https://thefierofactory.com/

The Fiero Store:
https://www.fierostore.com/



Well its not technically apart of the distributor so there is no way someone removed it. Its a piece of the wiring harness that happens to bolt into the distributor. if it wasn't broken it would have been permanently soldered in parallel with the pink and black line coming from the coil.

I will definitely give them a call and see what they have. It seems like this is the only fiero to have this capacitor or resistor or whatever. lol.

I eagerly await your response patrick.

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Report this Post02-21-2023 10:15 AM Click Here to See the Profile for 82-T/A [At Work]Send a Private Message to 82-T/A [At Work]Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dukesterpro:
It seems like this is the only fiero to have this capacitor or resistor or whatever. lol.


It is, definitely... 1984, and maybe a run of 85s. But that said, it does not mean it's the only GM car that has them. I would suspect there are other GM cars from say, 1982-1984 that also used that same distributor. I'd guess if you took a look at the 1984 Pontiac Grand Am with the 2.5, you'd probably also see the same distributor in there. GM tended to use all of these things across multiple car lines over the years. Like... the ESC that was used in the 80 Corvette also found its way into the Trans Am, Camaro, and even pickup trucks.

EDIT: I would guess that GM changed this for the 1985 model year because of reliability issues. I'd have to assume that having it mounted inside the distributor caused premature failure.

[This message has been edited by 82-T/A [At Work] (edited 02-21-2023).]

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Dukesterpro
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Report this Post02-21-2023 05:44 PM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post
Something interesting happened. I was looking at another Fiero for sale and my 84 was idling, high, 1600 rpms, when I got in and took off. It stumbled a bit for the first time tripped a code. Code 42.

I stopped the car and when to look in the back. Nothing seemed wrong. Still idled strong just high. Code went away after a restart. Oddly enough the engine idled correctly, at regular temp for the first time in a long time for about 30 seconds. I was standing there watching it. When all of a sudden it climbed right back up to 1600 rpm. Like someone lightly stepped on the throttle. No one was in on or near the car. Weird Weird Weird.

Fiero Factory doesnt know what Im talking about regarding that capacitor/resistor and I cant get fiero factory to pick up.

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Report this Post02-21-2023 09:08 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dukesterpro:

...all of a sudden it climbed right back up to 1600 rpm. Like someone lightly stepped on the throttle. No one was in on or near the car. Weird Weird Weird.


Not really all that weird, as that's what the IAC valve's job is when commanded to do so. Something is triggering the ECU to give the command. The next time the engine appears to be idling at the correct speed, unplug the harness from the IAC valve and see what happens.

I took some pictures of my 84's distributor (which I'll post this evening), but have nothing conclusive to share at this point.

[This message has been edited by Patrick (edited 02-21-2023).]

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Report this Post02-22-2023 12:59 AM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post


That's a photo of my '84 parts car. I have no way of knowing for sure, but I believe this is the original distributor... and it's the "newer" style. I suspect all 84's came with this style distributor.

 
quote
Originally posted by 82-T/A [At Work]:

No, that's definitely not the case. I bought a 1984 Fiero 2m4 back in the day (mid 90s) that was 100% all original. I also had a 1985 Fiero 2m4 that I bought at auction that was also all original. I've probably futzed through at least ~100 Fieros in the junkyard, and I can pretty confidently say that all the Fieros that were sold, came with the original style of "pickup" rotor as you posted in that image. The newer one with the triangular points within the ring is definitely the newer style.

EDIT: But back on the distributors... to be perfectly clear... no Fiero ever "came from the factory" with the distributor that has the star of David pattern. They all came with the one that looks like little points sticking up. But the "star of David" design is a NEWER design.



I'm still not convinced. Can you find a single picture online of an '84 duke "older" style distributor? If no Fiero ever "came from the factory" with the newer style distributor, there must be tens of thousands of the older style distributors still out there. Todd, I think your memory is playing tricks on you and it was actually "older" style distributors on 2.8 V6s that you're thinking of.

Dukester... in my image above, it's pretty obvious that this distributor has been tampered with (years ago by me). Where exactly was that unknown component mounted on your original distributor? On the outside of the body?

Online image of a Cardone '84 distributor...

[This message has been edited by Patrick (edited 02-22-2023).]

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Report this Post02-22-2023 07:48 AM Click Here to See the Profile for 82-T/A [At Work]Send a Private Message to 82-T/A [At Work]Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

That's a photo of my '84 parts car. I have no way of knowing for sure, but I believe this is the original distributor... and it's the "newer" style. I suspect all 84's came with this style distributor.

I'm still not convinced. Can you find a single picture online of an '84 duke "older" style distributor? If no Fiero ever "came from the factory" with the newer style distributor, there must be tens of thousands of the older style distributors still out there. Todd, I think your memory is playing tricks on you and it was actually "older" style distributors on 2.8 V6s that you're thinking of.


I love you man, you know that, but respectfully, you would argue about ice with an Eskimo. I'm not sure what the point is, this is the better design, and nearly all the new rebuilt distributors have this style. It's the one he should have and would want to get.


Dukespro, wish I could help, but honestly... you're missing the condenser... which is important for ensuring a clean signal to the ECM for timing. I used to have a 1984 Fiero Service Manual... I may still have it in storage if you feel like waiting that long. You might be able to find it online too... I just did a quick search and couldn't find it in PDF format. But this is it basically: https://www.themotorbooksto...175c90b69bdbe3d83819

It'll literally have the part numbers, exploded diagrams, and everything you will need to diagnose and identify the part that you're missing. The problem is that in 1984, it was basically the only year that Fiero had that configuration specifically like that. As I said though, if you can find a U-Pull-It or LKQ junkyard near you, you might want to check to see if there are other cars from that year... something like 1982-1984, either as a Chevy S-10, Pontiac Grand Am, Oldsmobile (whatever it was), etc... basically, anything with a Duke in it, and I guarantee to you that you'll be able to find the parts you're missing.


EDIT: I literally just ordered an original (reprint) of the service manual for my 1987 from that site. If you can swing it, it's worth the price. There's a lot of experience here on the Fiero List, but nothing beats the original service manual for things like this, especially with a 1984... which is probably my favorite year. I know it may not seem like it, but in 1984, the Fiero had a lot of little nuanced parts that none of the other years had (or were discontinued a few years after). Like the threshold name plates (I think, gone by 86?), or the headrest speakers (gone by 86), the one-year only black buttons (84 only), with several interesting seat combinations. They even had fleece seats, which were totally wild looking, last year of those was 1985. There was also a super-rare mirrored sunroof (not sure whether this was good or bad) in 1984. There were some issues too... but 1984 was truly a unique year. Man... I'm tempted to go buy one now.


Ok, just found part of it, go to page 107 (by looking at the pages, not the actual PDF page number):

https://www.fieroinfo.com/m..._Troubleshooting.pdf


It lists it as a "Radio Noise Capacitor"

When looking at Summit Racing, I see a list of possible options: https://www.summitracing.co...se-filter-capacitors


ALL the GM-style ones seem to be special order. I don't really see anything listed for L4/151, but it could just be because they don't seem to care enough to even bother to list it (I've seen this before).

[This message has been edited by 82-T/A [At Work] (edited 02-22-2023).]

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Report this Post02-22-2023 09:13 AM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post
First I want to thank 87 and patrick. You guys have been wonderful.

87 that book is going to be a tremendous help. That's really what I was looking for, and being new to this, I had no idea that existed. The big thing was identifying the name and part number. Which you did. I knew it wasnt exactly a condensor, due to it being fed on the solid 12 volt line. It had to be some sort of filter. I think that will help me get started.
Patrick, the part I am looking for it on bolted to the distributor, inside the housing, and wired in parallel to the purple and black wire going to the + pin on the 3 pin side of the ICM. Best thing that could be done is if you could carefully remove it by clipping the wire and measuring the capacitance of the filter so i match up an identical one from 87s provided material

[This message has been edited by Dukesterpro (edited 02-22-2023).]

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Report this Post02-22-2023 09:18 AM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post

Dukesterpro

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Ok after some research this is not my problem. All this capacitor does is filter noise out of the charging system to prevent feedback to the radio. Its not required to have the car run right if your radio has noise reduction built into it. (I have a touchscreen radio with all that jazz already built in) later Fieros apparently didn't have these filters when they went to the more modern pushbutton style radio. Damn

I'm back at square one. However, 87s reference material claims I should have a tach filter. Which I thought I didnt. I might need to go back and look harder.
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Report this Post02-22-2023 10:28 AM Click Here to See the Profile for 82-T/A [At Work]Send a Private Message to 82-T/A [At Work]Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dukesterpro:

Ok after some research this is not my problem. All this capacitor does is filter noise out of the charging system to prevent feedback to the radio. Its not required to have the car run right if your radio has noise reduction built into it. (I have a touchscreen radio with all that jazz already built in) later Fieros apparently didn't have these filters when they went to the more modern pushbutton style radio. Damn

I'm back at square one. However, 87s reference material claims I should have a tach filter. Which I thought I didnt. I might need to go back and look harder.



To be clear, the filter definitely ALSO does that, but it can also have an effect on the performance of the engine due to interference with the ECM. I'm not looking at the chart in front of me, but without that radio noise suppression filter, it's not grounding out a wire that otherwise should be ground. Again, I'm not looking at it, but that piece that comes out of the distributor has two leads going to it. One grounds out, and the other continues on, does it not? With it missing, are there not connections which are not being completed?

You do also want a tach filter, without one, the ECM may not be getting a good signal to adjust timing.
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Report this Post02-22-2023 11:36 AM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post
That filter grounds out right there. From 12v purple and black to the distributor housing. 2 leads.


Im wondering if my tach filter is there and I just dont see it. Its starting to bug me that I know this harness has not been modified and yet I dont see a tach filter or evidence of one at all.

[This message has been edited by Dukesterpro (edited 02-22-2023).]

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Report this Post02-22-2023 11:54 AM Click Here to See the Profile for ArthurPealeSend a Private Message to ArthurPealeEdit/Delete MessageReply w/QuoteDirect Link to This Post
I think that's a capacitor?

[This message has been edited by ArthurPeale (edited 02-22-2023).]

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Report this Post02-22-2023 12:15 PM Click Here to See the Profile for 82-T/A [At Work]Send a Private Message to 82-T/A [At Work]Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dukesterpro:

That filter grounds out right there. From 12v purple and black to the distributor housing. 2 leads.

Im wondering if my tach filter is there and I just dont see it. Its starting to bug me that I know this harness has not been modified and yet I dont see a tach filter or evidence of one at all.



Yes, ok... that's what I thought. So if I'm not mistaken, not having that plugged in or attached properly (or a failed one), is likely leading to a circuit not being completed. When you say purple and black, you mean black and purple as the 2 leads? I don't know what it does, but it's possible that maybe those two connect somehow within the radio noise suppression filter. So without it... it's not making that connection. You definitely want this.

Yeah, and there should be a tach filter... maybe it's serving as both? I don't know... it's kind of the same thing.


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Report this Post02-22-2023 12:45 PM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post
Its a black wire with a purple stripe. Its sole purpose is to provide 12 volts from the coils 12 volt supply the ICM.

My nearly completed CET degree is making me think that this is simply a form of back-emf protection so you don't hear whining over the radio from the ICM's micros working.

This capacitor doesn't appear to make any connection, since its run in parallel to the plug. All that happens is you have a bit more noise in the electrical system. Further, when I plugged my old radio back in, it makes a whining noise it never used to. I did find a replacement capacitor just in an electrolytic flavor instead of ceramic. Its on the way so I guess I am going to have to put up or shut up.

Can't wait to do a bunch of more work and find out you were right all along. lol.

I ordered a scanner from OBDDiagnostics today. Its time to get serious. In the mean time, I'm am going to try to locate that tach filter. It has to be there, because the tach worked really really well when I first got the car.

I will keep everyone posted. Please keep feeding me ideas and information if you think of anything. This is been very informative and I feel that all these ideas, even if they weren't my solution may be a valuable resource to others in the future. Especially as the popularity of the 84 seems to be on a uptick. At least in my area.
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Report this Post02-22-2023 02:26 PM Click Here to See the Profile for 82-T/A [At Work]Send a Private Message to 82-T/A [At Work]Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dukesterpro:

Its a black wire with a purple stripe. Its sole purpose is to provide 12 volts from the coils 12 volt supply the ICM.

My nearly completed CET degree is making me think that this is simply a form of back-emf protection so you don't hear whining over the radio from the ICM's micros working.

This capacitor doesn't appear to make any connection, since its run in parallel to the plug. All that happens is you have a bit more noise in the electrical system. Further, when I plugged my old radio back in, it makes a whining noise it never used to. I did find a replacement capacitor just in an electrolytic flavor instead of ceramic. Its on the way so I guess I am going to have to put up or shut up.

Can't wait to do a bunch of more work and find out you were right all along. lol.

I ordered a scanner from OBDDiagnostics today. Its time to get serious. In the mean time, I'm am going to try to locate that tach filter. It has to be there, because the tach worked really really well when I first got the car.

I will keep everyone posted. Please keep feeding me ideas and information if you think of anything. This is been very informative and I feel that all these ideas, even if they weren't my solution may be a valuable resource to others in the future. Especially as the popularity of the 84 seems to be on a uptick. At least in my area.



I mean, you've basically replaced everything at this point! Haha...

But I think you said it idles pretty well, minus the slightly high idle? That still confuses me. Did you ever check the EGR? Can't remember if you said that.
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Report this Post02-22-2023 02:33 PM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post
Idles strong, just at 1500-1700. Doesn't high idle when cold, only when hot. Like the high idle is reversed. Runs good, under half throttle. The more rpm I have to more throttle pedal I can use. If I push the throttle down to fast it bucks and occasionally pops out the intake. Otherwise runs good. Hell I was cruisin at 85mph for over 200 miles without a hiccup. Unless I pushed the throttle down to far. (Think load related vs throttle position, Low RPM + High Throttle = Misfire. High RPM + High Throttle = Good Running)

Everything thats been replaced so far.

Distributor
Pickup Coil
Ignition Coil
Cap
Rotor
Wires
TPS
ICM
IAC
MAP
EGR
Vacuum Lines
Fuel Pump
Fuel Filter
Coolant Temp Sensor (ECM)

This car is a veritable ship of theseus. Im starting to think fuel now? I havent replaced the injector.

[This message has been edited by Dukesterpro (edited 02-22-2023).]

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Report this Post02-22-2023 07:18 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dukesterpro:

Everything thats been replaced so far...


And all before you've done a very basic tuning requirement... timing the ignition! Dukester, I'm not trying to be critical, but this makes absolutely no sense to me.

I've contacted a friend of mine who's an electronics wizard, and who had an '84 Fiero for years (and who currently has a Formula). I'm hoping he can supply us with some insight. [EDIT] I just realized (after looking up some ancient posts on a local Fiero club's forum) that my friend had an '86 duke. Heck, they all look basically the same. Anyway, he might still be able to help with identifying that component.

In the meantime, is there no merit in what ArthurPeale found and posted? The actual page for the item (T8349) is Here.

[This message has been edited by Patrick (edited 02-22-2023).]

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Report this Post02-23-2023 09:43 AM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

And all before you've done a very basic tuning requirement... timing the ignition! Dukester, I'm not trying to be critical, but this makes absolutely no sense to me.

I've contacted a friend of mine who's an electronics wizard, and who had an '84 Fiero for years (and who currently has a Formula). I'm hoping he can supply us with some insight. [EDIT] I just realized (after looking up some ancient posts on a local Fiero club's forum) that my friend had an '86 duke. Heck, they all look basically the same. Anyway, he might still be able to help with identifying that component.

In the meantime, is there no merit in what ArthurPeale found and posted? The actual page for the item (T8349) is Here.




And I set the timing! I forgot to mention that dont yell at me, lol. 8 degrees at 1 and 4 and split the dfference.


ArtherPeale information was great, but the problem is no where on the returned google searches does the datasheet or webpage for the actual component does it list T8349. Meaning I can't be sure if its actually a "T8349" or google showing me something close. That's also a polyester capacitor, the one on my distributor was ceramic. Might be a newer version, the actual material type doesn't matter here. But without knowing its actual uF and V ratings for the original I cant put that one on.

[This message has been edited by Dukesterpro (edited 02-23-2023).]

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Report this Post02-23-2023 11:31 AM Click Here to See the Profile for 82-T/A [At Work]Send a Private Message to 82-T/A [At Work]Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

And all before you've done a very basic tuning requirement... timing the ignition! Dukester, I'm not trying to be critical, but this makes absolutely no sense to me.

I've contacted a friend of mine who's an electronics wizard, and who had an '84 Fiero for years (and who currently has a Formula). I'm hoping he can supply us with some insight. [EDIT] I just realized (after looking up some ancient posts on a local Fiero club's forum) that my friend had an '86 duke. Heck, they all look basically the same. Anyway, he might still be able to help with identifying that component.

In the meantime, is there no merit in what ArthurPeale found and posted? The actual page for the item (T8349) is Here.



Oh man, he hasn't timed it yet? Yeah, you definitely want to do that.

By the way... this thread is killing me. All of these pictures and looking up stuff about 84s... I'm like... very close to buying a 2nd Fiero, that's an L4... for my daughter. My wife thinks it's a horrible idea, but my daughter absolutely loves the look of the car. I showed her a picture of it and she was like... OMG, this car is amazing, and it has pop-up headlights. Plus, she wants to learn to drive stick for her first car.

She's 14, and for some insane reason, they let 15 year olds drive here in Florida... so she'll be driving in less than a year... I figured this could be a daughter-father bonding moment.

I'm such an idiot...
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Report this Post02-23-2023 12:48 PM Click Here to See the Profile for DukesterproSend a Private Message to DukesterproEdit/Delete MessageReply w/QuoteDirect Link to This Post
After all this pain and suffering, I still would recommend this car.

Its never run perfectly, but it always runs.

Its never not delivered me to work, nor failed to shuttle me home.

As long you and her have the patience to deal with these quirks. Go for it. She will never forget it.

Just teach her good defensive driving. Stay away from everyone always.

As an added bonus the iron dukes guarantees[i] that she will never get a speeding ticket.
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Report this Post02-23-2023 01:40 PM Click Here to See the Profile for ArthurPealeSend a Private Message to ArthurPealeEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dukesterpro:

ArthurPeale information was great, but the problem is no where on the returned google searches does the datasheet or webpage for the actual component does it list T8349. Meaning I can't be sure if its actually a "T8349" or google showing me something close. That's also a polyester capacitor, the one on my distributor was ceramic. Might be a newer version, the actual material type doesn't matter here. But without knowing its actual uF and V ratings for the original I cant put that one on.



It was also the -only- result I could find for that number. I wasn't even sure if that was the actual component, despite the obvious physical similarity
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Report this Post02-23-2023 05:06 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dukesterpro:

And I set the timing! I forgot to mention that dont yell at me, lol. 8 degrees at 1 and 4 and split the dfference.


And that was with the ALDL jumper in place? Hey, I've got to ask!

 
quote
Originally posted by Dukesterpro:

ArtherPeale information was great, but the problem is no where on the returned google searches does the datasheet or webpage for the actual component does it list T8349. Meaning I can't be sure if its actually a "T8349" or google showing me something close.


It's interesting to note, that if a Search is run at the site itself for "T8349", that this capacitor shows up... so it's not just Google that indicates this item is there. However, it is odd that the number "T8349" is not actually indicated anywhere in the part's literature.



 
quote
Originally posted by Dukesterpro:

But without knowing its actual uF and V ratings for the original I cant put that one on.


And we've hit a snag in regards to that... as even if I can locate this capacitor at my end, I have no way of determining it's specs. I asked my friend who's familiar with electronics if my multimeter has the capacity of doing these measurements (I sent him a photo of my multimeter)... and it doesn't. (And he's currently a thousand miles away from here, so it's not like I can use his multimeter.) So... we're back to square one. I'm of the opinion that this capacitor is only there to smooth things out for the tach, but also fully admit that this is above my pay grade.

[This message has been edited by Patrick (edited 02-24-2023).]

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Report this Post02-23-2023 05:17 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post

Patrick

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quote
Originally posted by 82-T/A [At Work]:

By the way... this thread is killing me. All of these pictures and looking up stuff about 84s...


And I bet you still haven't found an image of an "older" style '84 duke distributor... despite the fact that 136,840 1984 Fieros were produced and sold.

 
quote
Originally posted by 82-T/A [At Work]:

...to be perfectly clear... no Fiero ever "came from the factory" with the distributor that has the star of David pattern. They all came with the one that looks like little points sticking up. But the "star of David" design is a NEWER design.

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Report this Post02-23-2023 05:31 PM Click Here to See the Profile for PhatMaxSend a Private Message to PhatMaxEdit/Delete MessageReply w/QuoteDirect Link to This Post
If the cap is just for filtering you could put any cap in there as long as the minimum spec is the same or a higher value is used. The voltage can be higher as well as the uF…….just have to find the right size to fit.
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