Not a ThirdGen, but GM 2.5L 4-banger/TBI300. '84 Fiero, 8-bit 4KHz processor, no IAT sensor (by design), experiencing intermittent stalling, poor idle, no restart. Had it towed today and almost stopped at the recycler on the way....

I have retrieved all of the following DTCs in one trip:

Code 12 - (DUH);
Code 13 - O2 sensor signal loss or problem;
Code 15 - CTS low temperature fault;
Code 33 - MAP pressure low (vacuum high);
Code 34 - MAP pressure high (vacuum low - *the opposite of above);
Code 44 - Lean O2 sensor reading;
Code 45 - Rich O2 sensor reading (again, the opposite of above)

Bosch oxygen sensor is a few weeks old, Delco MAP is new, distributor is new, fuel pressure is 19 PSIG, CTS meters O.K. compared to gauge reading of coolant temperature, injector (all ONE of them) is new, IAC is clean, TPS is new, all gaskets down to the crank are new, all hoses are in good condition or new, ECM is well grounded, engine ground straps are good, positive bus voltage is 14.4VDC at idle, ECM connections are clean and tight, timing is 2° advanced beyond OEM base setting, fuel tank is 3/4 full and fuel is fresh 94 octane.

PROM is stock, compression is good (150), plugs are new and correctly gapped, wires, cap and rotor were new with the distributor. Coil has been changed.

I'm running out of parts to change and ideas. I'm getting frustrated with this piece of S**T TBI system, and it's unreliable, assumptive nature. I'll take a MAF any day. This system is as about as sophisticated as a f'ing wick stuck into a can of raw fuel and draped into the intake. I've had better luck with even the worst example of carburetion, the Holley 4BBL 4160. I'm about ready to send a thermonuclear token of my appreciation to the GM powertrain boys in remembrance of this fine engineering example.

How the f''k do you get these things to run worth a rats *** ?

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Later,
Vader
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"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

i used to have a fiero check in the ecm and see if their is any pysical damage. if their is check your coil sometimes when they go out they screw with the ecm

 

find a scantool. so that you can monitor thost codes a little more in depth.

Is that the correct fuel pressure setting. Im not familiar with 4cyl tbi, but that would be high for us v8ers.

might want to double check cts.
and what do your plugs look like now.

more info should help, hopefully GMtech will catch this post.

 

Does anyone make a good scantool thats not laptop based and a billion dollars?

Kelly 'GhoSSt' Rosato

 

Gho, I use, among others, an AutoXray that is specific to OBDI GM's, I think it was/is like $179? Pretty nice and easily hand held but the screen isn't as big as my SnapOn or a laptop but Bang-for-the-buck it cannot be beat... Especially for a first scan tool. It can record, too, which makes driving/tuning at the same time a little easier.

 

At least it isn't a Mercury outboard! I put up with 12 years of similar B.S. from one of those and (get this) Mercury Marine has no e-mail address!! Because they know what kind of letters they would be getting!

Anyhow, when you are getting a no restart, is the injector spraying fuel during crank? I agree that 19 PSI pretty high, esspecially at idle. I would turn it back down to 12-13 FOR NOW, then I'd take a good look at your primary ignition, and after that, I would go shopping for a new ECM. The ECM uses the pickup coil as a reference for the injection of fuel. If it gets a poor signal or no signal, your injection and ignition will both suffer. If you have no injection while cranking during a no restart, I would go straight to the pickup coil.

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'83 Trans Am. 400 CID, 224/234 crane cam, Summit aluminum roller rockers, hand ported intake, home bored 2.09" (53mm) throttle bodies, MSD 454 injectors(75 lb/hr), Holley 255LPH fuel pump, custum modded FPR w/Vacuum port added, Edelbrock TES headers, empty cat, SLP 3" stainless steel cat back, stock ECM & chip. Borg/Warner T-5 World Class, 12" Corvette rotors and clipers, GTA 16" wheels, South Side Machine subframe connectors, 1LE sway bars, 3.45 ring and pinion, Alpine sound.
Best E.T. 13.532
Best MPH 102.24

[This message has been edited by Tom 400 CFI (edited January 03, 2001).]

 

Vader,
About 10 years ago I was heavy into the Fiero world. I owned a '86 Fiero 2M6 (4-speed 2.8 liter MPI V6), and worked on different types of Fieros. I kind of wish I still had one, fun little cars. Most of the folks who I knew who had continued problems with the Fiero's 2.5 liter iron dukes after replacing many parts in the fuel system, it usually turned out to be a ECM problem. Especially when it runs good one minute and then starts sputtering and stalling the next, or stalls out of the blue. Try diagosing the ECM with some test equipment. If it turns out to be the ECM and you don't want to pay for a new one. You probably can get a good functioning ECM out of a '84 junk yard Fiero, that would allow you to get your Fiero up and running yet not break your wallet.

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Disco Man

1982-83 Cross-Fire Trans Am Site: http://members.xoom.com/the305cfi/

1979 (L78/W72) 10th Anniversary Trans Am
1982 (LU5) Trans Am

 

Also I forgot to mention, if the ECM checks out ok, it probably is the pickup coil like Tom mentioned.

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Disco Man

1982-83 Cross-Fire Trans Am Site: http://members.xoom.com/the305cfi/

1979 (L78/W72) 10th Anniversary Trans Am
1982 (LU5) Trans Am