I know it is enabled in my 85GT prom and would guess it is in all. It's takes the place of the Accel pump in a carburetor to give the engine extra fuel when you step on the gas otherwise you would go to lean.
On mine I know it actually has a couple steps in the amount of fuel depending on MAP value and TPS position. IE the more you step on the gas and the greater the load the more gas.
On a carb the power piston (accell pump) works along with the vacuum controlled metering rods to increase fuel. They have the prom setup to act the same way.
Was looking at the O2 at idle and it is a little lazy but then I looked at the MAP. 50 at idle is a little unreasonable in my book. Usually at idle I'm use to seeing a MAP run around 30. This would be moving you up in the VE table adding fuel since it thinks there is load on the engine. Weird! You have a spare MAP you could try? Or a vacuum gage to see what your reading? crack in the line to the MAP?

[This message has been edited by Dodgerunner (edited 11-18-2008).]

quote Originally posted by Dodgerunner: Was looking at the O2 at idle and it is a little lazy but then I looked at the MAP. 50 at idle is a little unreasonable in my book. Usually at idle I'm use to seeing a MAP run around 30. This would be moving you up in the VE table adding fuel since it thinks there is load on the engine. Weird! You have a spare MAP you could try? Or a vacuum gauge to see what your reading? Crach in the line to the MAP?

Rory, just so this is clear to me - Does a lower vacuum result in a higher MAP reading?

I do have several MAP sensors I can try.

Okay, it's not raining... I'm going outside to poke around with the GT.

Correct, low vacuum (high load) = higher voltage.

[This message has been edited by Dodgerunner (edited 11-18-2008).]

I'll jump into this party late, but I'm guessing that you won't pass smog without a functioning converter. I'd buy Rodney's replacement if it's a three way converter(I don't remember if it is). I have a Summit 2 way on mine, but it barely passes the NOx every time.

I've made one deduction, and one discovery.

First... Rory, I'll bet dollars to donuts that your Fiero is a standard. Why do I say that? Well, I witnessed today while having the laptop connected to the GT that the MAP readings were around 37 at idle. (I had put a different MAP sensor in from an '84 Duke.) I thought this was interesting because it appeared to be closer to the MAP readings (30) you had reported with your Fiero. So I went for a drive, and while I was driving I could see that the MAP readings were back up to 50 or so while I was sitting at a stop light. This puzzled me for a moment until the little light went on above my head... But of course, with my Fiero being an automatic, the MAP reading is higher while it's in Drive because of the drag! When I put the GT in Park, the MAP readings went back down to around 37. What do you think, does this make sense and is a MAP reading of 37 acceptable while in Park?

Second... My discovery. I wanted to bump up the timing a bit as I had previously leaned more towards 8 BTDC than 10 and I wanted to try instead be a tad closer to 12. (I find it difficult to see EXACTLY where the timing mark is in relation to the degree indicators.) By this time it was getting dark, but I thought what the heck, it'll make it easier to see the timing mark. Well, that's not all I saw! All three metal heat shields on the rear most spark plugs were literally dancing with little sparks jumping off them to the heads! I find it difficult to understand how the engine ran so well with all this arcing going on. So I removed all six metal heat shields and I now see no evidence of arcing. These Bosch Ultra Premium 7mm wires were brand new before the GT was put in underground storage for six years, so I’m not sure if this is a true indication they need replacing or not. I have an MSD Blaster coil installed and the NGK UR5 plugs are gapped at .060". Comments?

An image showing some of my ignition components...



By the time we finish with this engine (this is a group project, you know ), it’s going to have double the power with twice the gas mileage!

Okay, after the changes I mentioned above, I took a short run on the freeway with the laptop connected. For Rory or anyone who finds this stuff of interest , Here is the WinALDL log. Thanks for looking!

Prior to creating this latest WinALDL log, I filled the tank so that I could work out what kind of mileage I was getting after unplugging the cat. Arrgh, it's still only 15.5 mpg!

Sure that's better than the 9.4 mpg I was getting prior to unplugging the cat, but it's still pathetic. I'm hoping the latest adjustments I've made (see the second post above this one), including replacing the 180 with the 195 thermostat, will do some good. Otherwise, I may have to get this custom PROM re-done.

[This message has been edited by Patrick (edited 11-19-2008).]

I wish I made 30+ mpg with my 2.8, but that's all it is. A wish. I get about 24 in town. Keep whittlin'. You will get it.

The good news...
I passed the smog test !!!!!!!!

The readings were relatively good...



Keep in mind this was with NO cat. (Well, there is a cat on the car, but it's completely hollow!)

The bad news...

Even with the GT running just fine (supposedly) and passing the smog test no problem, the gas mileage is still absolutely pathetic - 14.36 MPG with my last fill up, and that's with me driving like an old lady.

I've been taking it ever so easy on the gas. I'm even putting the car in neutral every time I slow down and stop so that the transmission isn't putting any drag on the engine while I'm sitting at a light.

I may end up re-connecting the EGR and re-installing the stock PROM to see if that helps as this just isn't good enough.

i dont know if you have dont this but...

1 take your plugs out and toss them, get a new set of ngk's and gap them to .47 yes .47
2 get rid of that msd blaster they are junk, and get a NOS one from a 92 buick roadmaster 5.7 350
3 if your wires were arc ing put the heat shields back in and get a new set of wires 8mm core if you can afford them
4 delete the cat all together put a nice pipe in its place, empty cat is causing exuast flow turbulance.
5 egr... car will run better with it and get better gas mileage... thats up to you i dont like them either
6 a cooler running engine will use more fuel, again do what you want 195d is the opt temp for the engine but you will lose power
7 put some rubbing alc in your tank when you goto emisions 1/2 tank 1 bottle = 3 cats on your car works every tim

oh and you will lose about 7mpg with an auto... sorry.... lol put a nice shift kit in it and a switch to bypass lock up so that when you are on the highway you can just lock the tranny in gear (if you do this mod be careful if you forget to flip the swich in the city or before you come to a stop car will stall.)
and stay away from the dickman cats they are just uni's i have done a few of them now and everytime it has been a uni, magana flow high flow cat is worth the pennies if you really want one.

[This message has been edited by Fieronum6 (edited 12-05-2008).]

Fieronum6, thanks for all the great suggestions. Some I agree with, some I don’t. However, I believe they’re all worthy of discussion.

quote Originally posted by Fieronum6: take your plugs out and toss them, get a new set of ngk's and gap them to .47 yes .47

My plugs are new NGK UR5, gapped to .060" as suggested by many people here when used with a Blaster coil.

I don’t think you’re suggesting I gap them to almost half an inch. I’m sure you mean .047"

Why .047"?

quote Originally posted by Fieronum6: get rid of that msd blaster they are junk, and get a NOS one from a 92 buick roadmaster 5.7 350

What is the problem with the MSD Blaster coil?

And what is special with the NOS one from a 92 buick roadmaster 5.7 350 compared to a stock Fiero coil?

quote Originally posted by Fieronum6: if your wires were arc ing put the heat shields back in and get a new set of wires 8mm core if you can afford them

I actually had bought a set of 8.8mm Accel wires on eBay, but the vendor said he “lost them” after the auction as I reported Here.

If the boots no longer arc without the metal heat shields on, and as long as the silicon plug boots don’t melt, is there still a need to replace the wires?

quote Originally posted by Fieronum6: delete the cat all together put a nice pipe in its place, empty cat is causing exuast flow turbulance.

Now that I find difficult to believe.

The effect may be minimal, but an empty cat should work as an expansion chamber. Hot exhaust gases get to expand and cool down as they pass through an expansion chamber. When they cool down, they also contract, thus taking up less space. Less volume means less restriction as these gases pass through the rest of the exhaust system.

I would think that “exhaust flow turbulence” would be one heck of a greater problem occurring in the muffler!

quote Originally posted by Fieronum6: egr... car will run better with it and get better gas mileage... thats up to you i dont like them either

Yes, I’m considering reconnecting the EGR and putting the stock PROM back in the ECM.

quote Originally posted by Fieronum6: a cooler running engine will use more fuel, again do what you want 195d is the opt temp for the engine but you will lose power

I have a 195 degree thermostat currently installed and I have no immediate plans to put a 180 back in there.

quote Originally posted by Fieronum6: put some rubbing alc in your tank when you goto emisions 1/2 tank 1 bottle = 3 cats on your car works every tim

Well, I passed the smog test without a cat at all, so I won’t be needing any gypsy juice.

quote Originally posted by Fieronum6: oh and you will lose about 7mpg with an auto... sorry.... lol put a nice shift kit in it and a switch to bypass lock up so that when you are on the highway you can just lock the tranny in gear (if you do this mod be careful if you forget to flip the swich in the city or before you come to a stop car will stall.)

Installing a switch to force the tranny to lock in gear on the highway is an interesting idea. If I wasn’t doing 95% of my driving in the city, I’d install one right away!

quote Originally posted by Fieronum6: and stay away from the dickman cats they are just uni's i have done a few of them now and everytime it has been a uni, magana flow high flow cat is worth the pennies if you really want one.

Again, having passed the smog test without a (functioning) cat of any sort, the type of cat to use is a moot point (for me).

One alteration I am thinking of doing however (now that I know I don’t need a cat) is to put a true dual exhaust system on the GT. Call me a dinosaur, but I want something similar to the exhaust system on the V8s of my youth where both engine banks had their own exhaust pipes, mufflers, and tail pipes. I want true “stereo imaging” of the engine exhaust noise. Having two tail pipes coming out of a common muffler just isn’t good enough!

[This message has been edited by Patrick (edited 12-26-2008).]

quote Originally posted by Dodgerunner: Well the BLM now is staying down closer to normal. However you O2 is acting different. If you look at you rich/lean graph it should be a smooth saw tooth. You can see yours is jerky. That is due to the fact you O2 quits switching at times. It stops often at idle. Might be due to the cat being gone that it cools off quickly and stops working. You might also put your 195 stat back in and see what affect it has on the O2. Have to run, will look more later..

i have not yet read past this post, but i thought i would make a note that the ALDL readings on the O2 sensor is NOT an effective way to diagnose an o2 sensor. the ECM data feed is simply too slow to effectively see what the sensor is doing even on a modern car let alone one with a slower 25 year old computer. in order to really see what an o2 sensor is doing you would need a labscope. however you can see that the thing is working based on the fact that it IS fluctuating between rich and lean whick is correct operation.

------------------

Wyotech Sacramento Alumni. ASE A6, A8, L1 and Certified. CA SMOG License.
1987 Pontiac Fiero GT 5-speed
1987 Pontiac Fiero GT, 151,000 miles! decklid window, More pics of my 87 GT can be found here <-SOLD
1985 Pontiac Fiero 2m4 auto, 222K miles and counting <-recently lost to arson (6yo bro playing with fire) RIP!
2005 Jeep Grand Cherokee 3.7L 4x4, 72K <-Daily driver
A 4 year olds knowledge of science: No matter how much jello you put into a swimming pool you still can't walk on water.

ok here goes,

the gap has been dyno proven to have a better curve (smother)
the bigger the gap the skinnyer the spark and the less of a chance for ignition under load
msd blaster coils are junk because they sell you on the name, sure its higher voltage then stock but the amprage is lower amps is what does all the work
sorry to hear about ebay im going though that with my turbo fiero that i just sold dude wont pay....
the muffler does rob horsepower as for a dual setup i would like to do the same, there has to be some thoght put into it to keep the banks balaced. ill prolly just shade tree it and see how it sounds and go from there (-:
the hotter the engine the more efficent it can run

good luck, oh btw i still have that dual throttle body setup works ok but i sold the NA car too got something new in mind 50 bucks plus shipping?

[This message has been edited by Fieronum6 (edited 12-06-2008).]

quote Originally posted by Fieronum6: oh btw i still have that dual throttle body setup works ok but i sold the NA car too got something new in mind 50 bucks plus shipping?

Thanks for the offer, but no, I'm finding it enough of a task to keep the stock engine functioning properly without complicating things!

Patrick- Have an update for us? Or is 14mpg not a problem since gas prices went down?

Heh heh, let's just say I haven't been using much gas at all lately. This picture was taken yersterday and it's been snowing like heck all day today. This is NOT usual Vancouver weather.



When I'm finally able to drive the GT again, I plan on swapping the injectors with another set I have here to see if that makes any difference with the gas mileage. It may be awhile, but I'll report my progress (or lack thereof).

That picture explains a lot.

This is the time of year I am glad to be in the South. lol

[QUOTE]Originally posted by Patrick:



QUOTE]

Hey look! IT turned into a fastback...

quote Originally posted by Dodgerunner: Hey look! It turned into a fastback...

Hey Rory, it's an '86 GT... It was always a fastback!

Looks like it's not going anywhere very fast in that pic...

Are you getting the rain and warming that they are getting south of you?

quote Originally posted by Dodgerunner: Are you getting the rain and warming that they are getting south of you?

Yes, most certainly. The big problem now is flooding as the rain is combining with rapidly melting snow.

With storm drains being plugged by snow, there are now reports on the radio of several cars on local roads being swallowed up by three foot high "puddles"! I kid you not!

This shot was taken yesterday just before the rain started...

[This message has been edited by Patrick (edited 12-27-2008).]

quote Originally posted by sjmaye: Patrick- Have an update for us? Or is 14mpg not a problem since gas prices went down?

Okay, it's almost June and I believe the cold front has now passed...

I've done a few things to the engine. I've put the EGR system back into action. The custom PROM has been chucked and the factory unit has been reinstalled. The ignition has been timed "by ear" (it's quite a bit further advanced but with no pinging on regular gas). The tranny pan has been dropped and the fluid/filter has been changed.

I wanted to also mention that I did not replace the injectors, as a leak-down test demonstrated that they weren't leaking.

On my last tankful of gas, 22% of the mileage was around the city and 78% was on the highway. So, is it running any better now?

21.36 mpg

Still not the greatest, but a heck of a lot better than I was getting previously.

There's a few more things I wish to try to increase the mileage. I'll post here again in the weeks to come if I've got any further news to report...

[This message has been edited by Patrick (edited 05-29-2009).]

At least your car is running and it seems to be doing so reliably. There are many here that can't say the same.

Yes, it seems to run well, and since I put this replacement nose on, it also looks pretty good. (The '86 GT that this nose came off of had extra stripes all around it. I actually kind of like having the stripes just on the nose.) Too bad it's an automatic. For that reason alone I'll be selling this GT when I get another one of my Fieros roadworthy.

EDIT : aha answered my question

[This message has been edited by serealport (edited 06-21-2009).]