Its still doing it... just like a few other's cars on this board right now. It bucks and stumbles occasionally and seems to do it at lower rpms, but if you nail it, it almost always pulls thru to red line. Seemed like directr fuel problem but its not... unless its weak injectors (I don't know how to figure that ne out either).

*I read that the ECM goes in open loop at WOT... is that true? If so, could my ECM be bad, but let it run ok in high rpms because its "ignoring" the motor (open loop).

*Also, is there anyway to tell if my PROM is good. It has a Hypertech in it that was there when I bought it. Another guy had similar problems and it was his PROM. Anyone?

I appreciate all the help so far and the help that is still to come. Input welcome from all THANKS!!

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

Kinda sounds like my problem check it out https://www.thirdgen.org/messgboard/...ML/006739.html

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'87 Trans Am
305 TPI:
160 Degree Thermostat
TB Bypass
Accel 300+ 8.8 Racing Wires
Accel Super Coil
Bosch Platinium Plugs
Custom Ram Air with K&N

 

Dude, I've already told you how to find weak injectors with the cylinder balance test. It's either that or probably a bad EGR.

------------------
1990 IROC 350
Mods: Too busy trying to make it run right to mod it.
Airfoil, Dynomax cat-back, Accel coil, 180 t-stat, Bald Eagle tires,
Hypertech fan switch, Ruger P95DC, hot wife, new oil filter,
thick rubber floormats, towels in the seats.
18.0 @ 85MPH since I'm one big-a$$ MF
"It's better to have and not need than to need and not have."

 

Oh ****... thats right. I don't know what i was thinking! I think the EGR is fine though. I unplugged the solenoid and it made no difference at all. It will still run this way after a while. My dad says its not EGR related either. Its way too violent.(fuel or spark related)... and if it was the EGR it would probably pull thru I think. I still think it may be that darn ECM. We'll have to do that balance test too. The only thing is: could the injectors test out ok on the balance test, but be messing up only intermitently? because this problem is definately intermitent. It seems as if it does it after the motor gets in closed loop mode and after you've driven it a little bit. Whats the best way to clean the upper end and injectors? Besides taking it all apart? Thanks

------------------
'91 GTA:
www.fbody.com/members/91WS6GTA

 

GTA91, Last year I had that problem with my '92Z,after spending a lot of money(and I mean a lot!!!)it turned out to be dirty fuel injectors. Check those out first just to make sure even if you think their clean. Good luck

 

GEARHEAD-
Dirty injectors? How'd ya figure that one out? Did you run cleaner thru them at teh Schrader valve or what? Injector cleaner thru the tank? I need to try something like this b4 I pull them out. THANKS

------------------
'91 GTA:
www.fbody.com/members/91WS6GTA

 

What do ya'll think about my problem?

------------------
'87 Trans Am
305 TPI:
160 Degree Thermostat
TB Bypass
Accel 300+ 8.8 Racing Wires
Accel Super Coil
Bosch Platinium Plugs
Custom Ram Air with K&N

 

GTA91 - I've tried about every in-tank fuel treatment under the sun, all of them a complete waste of money IMO. With all I've spent on that worthless s@#t I could have paid for 30% of a new set of injectors . However, one of the kits that connects to the fuel rail may work better in some cases. I just skipped spending $80 for a kit to slap on the fuel rail in favor of new Accel injectors from Rich at www.cruzinperformance.com. He's excellent to deal with and my injectors will be here tomorrow (I just ordered them Tuesday). I figured why not spend another $150 and have all new stuff, and not take the chance that the rail cleaner won't work. You make your own call on that one.

jobryan - Off the top of my head, check the IAC, CTS, TPS and torque converter lockup (TCC). I still wouldn't rule out the EGR too since you didn't replace it yet.

 

Thanks Jethro I'll go ahead and replace it today.

------------------
'87 Trans Am
305 TPI:
160 Degree Thermostat
TB Bypass
Accel 300+ 8.8 Racing Wires
Accel Super Coil
Bosch Platinium Plugs
Custom Ram Air with K&N

 

I've been fighting the same problem for about 5 months now. Do you have any results from the injector, ECM, or EGR swap?

 

Check your ground wire! When I installed the L98 motor in my RS it would idle like crap, but when I stomped on it, the problems would clear. What was happening is the motor was rocking in the mounts, twisting the negative ground, causing a better connection. I bought a new ECM and everything. I really felt dumb when I found the negative ground on the engine block to be loose. I found it when I grabbed the smaller ground wire leading from the battery to the fender. Burnt my hand because the car was trying to pull all ground thru that tiny wire.

------------------
Rob P
89RSconvtZZ4TPI
Edelbrock Hi-Flow Intake
SLP Dual Cold Air Intake
1 5/8" Headers
Semi-Siamesed Runners
MSD6AL/relocated MAT/ AdjFPR/IROC frnt@rear swaybar/wonderbar/steeringbox/alum drvshaft/ Alston SFC/3:23posi disc rear/MAC LCA/H.Adams Panhard Rod/KYB struts/ shocks/
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

I had a similar problem on my TA...

it would run fine at idle and on accelleration... but chug and backfire at constant speed and decelleration...

turned out my rotor had lost one of the screws and busted a piece of it off... the only thing holding it in the center was the cap and the reason it would go good on accelleration was that the broken side was the notched side... so the little tab would catch the rotor on accelleration and let it slip out of place on decelleration causing the chuging...

i am sure that that probly isnt your problem though... just thought i would share...

later,
Chris

 

Ok, I JUST NOW finished fixing this same exact problem with my car. Turns out the o-rings on the fuel injectors were bad, and they were letting air get in. IE it makes a nasty vacuum leak. Turn the car on, while it's idling push on your injectors, if the idle comes up there you go. Listen for a vacuum leak noise, especially a whistle. Hope this helps.