1989 GTA LB9/700R4 high idle and shuts off. 73k miles
#1
1989 GTA LB9/700R4 high idle and shuts off. 73k miles
Hi all, have done a search and cannot find any new info to try to fix my issue. Once you start the engine, the idle automatically goes to 12-1500 rpm when its cold, over 1500 rpm when warm. Shift into gear and idle settles around 1000-1100 rpm. Seems to run well otherwise, but when it gets warm, you rev the engine slightly and it will die completely. The engine still will run liked a raped ape otherwise, but am having trouble figuring this issue out. So far I have:
Changed plugs- Ac Delco R45TS (gapped correctly)
Wires-Accel super stock
Cap and Rotor--AC Delco
Coil-- AC Delco
New CTS
New TPS--set at .54V and increases linear to 4.13V
Vader's IAC reset procedure
New thermostat--195F
All new Fel-Pro TPI intake gaskets
Checked and repaired any possible vaccum leaks
New fuel pump and filter
Also, I have tried to pull codes after everything listed above. I will get an SES light roughly 10 min into a steady drive but no change in running condition. I do have an ALDL cable and old laptop running WINALDL that I haven't yet tried to pull codes with but I did try the paperclip method and cannot get a code 12. SES light stays solid with jumper in place and KeyOn/EngineOff. Kinda stumped here and need a solution. I have never tried PROM tuning as I am a noob at that sort of thing but with the cable I can at least datalog. I have also taken a video of the engine warm and dying under light throttle that I can email or upload if need be. Thank you for any help that I receive! You guys have always been the kings of 3rd gen knowledge!
Changed plugs- Ac Delco R45TS (gapped correctly)
Wires-Accel super stock
Cap and Rotor--AC Delco
Coil-- AC Delco
New CTS
New TPS--set at .54V and increases linear to 4.13V
Vader's IAC reset procedure
New thermostat--195F
All new Fel-Pro TPI intake gaskets
Checked and repaired any possible vaccum leaks
New fuel pump and filter
Also, I have tried to pull codes after everything listed above. I will get an SES light roughly 10 min into a steady drive but no change in running condition. I do have an ALDL cable and old laptop running WINALDL that I haven't yet tried to pull codes with but I did try the paperclip method and cannot get a code 12. SES light stays solid with jumper in place and KeyOn/EngineOff. Kinda stumped here and need a solution. I have never tried PROM tuning as I am a noob at that sort of thing but with the cable I can at least datalog. I have also taken a video of the engine warm and dying under light throttle that I can email or upload if need be. Thank you for any help that I receive! You guys have always been the kings of 3rd gen knowledge!
#2
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Join Date: Jul 1999
Location: Adrian, Mi, USA
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Car: 1988 Pontiac Firebird Formula
Engine: 5.7 TPI
Transmission: 700R4
Re: 1989 GTA LB9/700R4 high idle and shuts off. 73k miles
Still sounds a lot like a vacuum leak...... disconnect the vacuum line from the brake booster, and plug it off.... see if anything improves.
#3
Re: 1989 GTA LB9/700R4 high idle and shuts off. 73k miles
, that is what keeps bugging me. I hear no hissing or anything from around the intake. Also tried the old spray starting fluid around the intake and see if the idle picks up more and it doesn't. I'm just kind of lost at this point. Will re-check after I get off the water today and re-update.
#5
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Join Date: Jul 1999
Location: Adrian, Mi, USA
Posts: 1,551
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20 Posts
Car: 1988 Pontiac Firebird Formula
Engine: 5.7 TPI
Transmission: 700R4
Re: 1989 GTA LB9/700R4 high idle and shuts off. 73k miles
I think if you ground A and B on the ALDL terminal in the car, and turn the ignition on, it should run the IAC all the way closed. Try that, and then disconnect the IAC, and see if the engine idles really low.
#7
Re: 1989 GTA LB9/700R4 high idle and shuts off. 73k miles
Any other ideas that I can try guys? This is a really frustrating issue to figure out. I threw an ALDL cable and a laptop at it to try and pull codes. It showed a MAF code, and had some really weird looking data showing up. I really hope the computer isn't dying, but I am out of things to try except for throwing parts on it.
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