Fun time today! Sudden rough running and check engine light (Page 1/2)
ArthurPeale SEP 05, 06:26 PM
1986 SE v6 2.8

I shifted into reverse earlier and it was running really rough, and the Check Engine light came on. Shifted into neutral and it shut off. Shifted back into reverse and it was fine.

I'd like to know what happened.

Jumpered the ALDL - code 33. Huh.

I just discovered a few things....

1) the recall for the pipe along the firewall was never done on this vehicle. Huh.

2) the front manifold is glowing a bit. It's never done that before now, that I'm aware.

3) for giggles, since I already had the paperclip in the ALDL, I tried to start it - it wouldn't. Fired right up as soon as I removed it, and ran like a top. Ran like CRAP if I put it back.
IMSA GT SEP 05, 07:11 PM
Sounds like the MAP sensor died.
ArthurPeale SEP 05, 07:17 PM

quote
Originally posted by IMSA GT:

Sounds like the MAP sensor died.



Maybe. It recovered within seconds, and is still running like a top.

I thought it was uncommon for them to die?
Patrick SEP 06, 02:26 AM

quote
Originally posted by ArthurPeale:

I just discovered a few things....

1) the recall for the pipe along the firewall was never done on this vehicle. Huh.



Why, what exactly did you find (or not find)? Post a photo.


quote
Originally posted by ArthurPeale:

...for giggles, since I already had the paperclip in the ALDL, I tried to start it - it wouldn't. Fired right up as soon as I removed it, and ran like a top. Ran like CRAP if I put it back.



Although your engine may appear to be running "like a top", that's very much a subjective observation. If the engine won't start with the ALDL jumper in place (which effectively retards the timing), something's not right.

Of course I don't know for sure, but it sounds to me like the ignition timing is set too retarded (or it was originally set correctly, but the clamp has loosened and the distributor has moved a bit). If a timing light were to show otherwise, I'd suspect the outer ring of the harmonic balancer has slipped, and the timing grooves on the balancer are no longer in the right place (in relation to the crankshaft).

[This message has been edited by Patrick (edited 09-06-2021).]

ArthurPeale SEP 06, 01:44 PM

quote
Originally posted by Patrick:

Why, what exactly did you find (or not find)? Post a photo.



It'll have to be later, but the line that goes from the air cleaner housing to the valve cover against the firewall, it's intact.



quote
Originally posted by Patrick:
Although your engine may appear to be running "like a top", that's very much a subjective observation. If the engine won't start with the ALDL jumper in place (which effectively retards the timing), something's not right.

Of course I don't know for sure, but it sounds to me like the ignition timing is set too retarded (or it was originally set correctly, but the clamp has loosened and the distributor has moved a bit). If a timing light were to show otherwise, I'd suspect the outer ring of the harmonic balancer has slipped, and the timing grooves on the balancer are no longer in the right place (in relation to the crankshaft).




It started once I removed the paper clip, then once put back, it would run poorly. Agreed that I'll have to do some investigating, this was just a prelim.
Xenoblast SEP 06, 03:17 PM

quote
Originally posted by Patrick:


Of course I don't know for sure, but it sounds to me like the ignition timing is set too retarded




I second this. My engine used to be 30 degrees retarded when i first got it, and it didnt feel any different then it does now except maybe some more torque on the low end. I only checked it out of curiousity. And my headers did glow red after only 2-3 minutes of running in diag mode.

It didnt idle on its own in diag mode, so i had a friend keep on the gas while i turned the distributer until it idled on its own. I then had him help me set it more precisely.

the reason why i know it was 30 degrees retarded is because it showed 10 degrees of timing out of diag mode, so the previous owner must of skipped grounding the connector

[This message has been edited by Xenoblast (edited 09-06-2021).]

Patrick SEP 06, 05:42 PM

quote
Originally posted by ArthurPeale:

...the line that goes from the air cleaner housing to the valve cover against the firewall, it's intact.



Well, that's fine. However, if the open end of that tube hasn't been capped off, then that's not fine.
ArthurPeale SEP 07, 05:00 PM

quote
Originally posted by Patrick:

Well, that's fine. However, if the open end of that tube hasn't been capped off, then that's not fine.



the tube isn't open ended; it goes directly from the air cleaner housing to the valve cover.

I'll see about snapping some photos soon. It's been a rough few days.

Interesting note: the gasket between the deck lid and rear window is still there.
Patrick SEP 07, 05:15 PM

quote
Originally posted by ArthurPeale:

the tube isn't open ended; it goes directly from the air cleaner housing to the valve cover.

Interesting note: the gasket between the deck lid and rear window is still there.



Sounds like your Fiero has never had the recall done to it. Rather unusual.

Does your engine then not have this newer style breather tube connected on the front side of your engine? (The end not connected in the photo plugs into a replacement snorkel).

[This message has been edited by Patrick (edited 09-07-2021).]

ArthurPeale SEP 08, 10:48 AM

quote
Originally posted by Patrick:

Sounds like your Fiero has never had the recall done to it. Rather unusual.




quote
Originally posted by ArthurPeale:

I just discovered a few things....

1) the recall for the pipe along the firewall was never done on this vehicle. Huh.




quote
Originally posted by Patrick:Does your engine then not have this newer style breather tube connected on the front side of your engine? (The end not connected in the photo plugs into a replacement snorkel).






Pretty sure not. I'll have to look.