Need help for 1985 C4
Thread Starter
Intermediate
Joined: Mar 2017
Posts: 43
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Need help for 1985 C4
Someone help me please. My '85 has a problem. It will idle just fine but when I try to accelerate it coughs, sputters and backfires. If I stay on the throttle it will catch up and run good. It is worse under load. Anybody have a solution for this problem? What should I be looking at? TIA
Team Owner
Joined: Sep 2001
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
First thing is pull the codes, if its acting up that bad there should be one set. Check FP at the rail at idle and with your hand on the throttle linkage, then watch with the engine turned off. TPS voltage too. Note most recent fuel MPG
Thread Starter
Intermediate
Joined: Mar 2017
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Ok. I was doing some checks that you guys suggested this morning and got some mixed and one unexpected results. First I could not get a voltage readings on any of the three wires going to the tps except the bottom one and it was giving a varying reading of .10 - .40 volts. Here is the unexpected part. I started the engine and then I realized that I had not reconnected the plug to the tps.and it was running the same as it does with the wires connected. Is this normal?
Burning Brakes
Joined: Nov 2000
Posts: 986
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Ok. I was doing some checks that you guys suggested this morning and got some mixed and one unexpected results. First I could not get a voltage readings on any of the three wires going to the tps except the bottom one and it was giving a varying reading of .10 - .40 volts. Here is the unexpected part. I started the engine and then I realized that I had not reconnected the plug to the tps.and it was running the same as it does with the wires connected. Is this normal?
With no TPS plugged in you should set code 22. Did it?
Pull. The. Codes.
Last edited by PacerX; Aug 22, 2019 at 11:03 AM.
Oil Producer
Joined: Apr 2014
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Drifting
Joined: Mar 2013
Posts: 1,952
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From: Venice Cali.
Put 1 small pin in the top two tps wires and turn the key on(no start) and the reading should be .54. The key is that when you turn the throttle it should climb smooth to 4. something.
Then put the paperclip in the top right 2 ports in the obd connector(a and b) then you will see code 12 one blink then 2 blinks, after that you will see any codes you have.
Good Luck!
Then put the paperclip in the top right 2 ports in the obd connector(a and b) then you will see code 12 one blink then 2 blinks, after that you will see any codes you have.
Good Luck!
