86 TPI problems
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Joined: Oct 2007
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From: Durant Ok
86 TPI problems
I was needing some help figuring out what is wrong with my car. The car is an 86 4+3. After it messed up and we got it home, I started it up to put it in the garage, anyways when I started it up it would idle but any throttle input would result in it stalling out or dying. We finally got it into the shop and I was messing around and unplugged the MAF and the TPS, after doing this the car will idle, and you can rev it up, it is running very rich now though. If you plug either the MAF or TPS back in it results in it stalling and dying. We tried replacing the computer but that didnt change anything, but when we were changing out the computer we discovered that the car had a Hypertech chip in it. Do you guys think that it might be the chip, or should I look elsewhere? Any input would be appreciated.
Team Owner
Joined: Sep 2001
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From: Athens AL
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It does this upon initial startup or all the time (i.e., even when hot)?
There are no SES lights showing?
There are no SES lights showing?
Race Director
Joined: Sep 2003
Posts: 16,835
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From: Database Error Indiana
The MAF has 2 relays that can cause trouble. I would replace them first. In the last 10 (100k miles) years I have replace them twice. Not sure whitch one was bad either time but they are cheap so its worth it.
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Joined: Oct 2007
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From: Durant Ok
Ok, so I replaced the relays and it helped it idle a little better but it still wouldnt rev up any. It threw a tps code so I went ahead and changed that too. Now, it wont start at all, it just cranks and acts like it wants to start but wont.
Team Owner
Joined: Jan 2003
Posts: 20,277
Likes: 236
From: Summerland B.C. Canada
After you replaced the TPS, did you calibrate it to .54 volts at idle ??
https://www.corvetteforum.com/techti...D=55&TopicID=2
https://www.corvetteforum.com/techti...D=55&TopicID=2
Burning Brakes
Joined: Apr 2004
Posts: 762
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From: Huntington ma
Generally speaking, and it's an over simplification, but...
If it won't respond to throttle with the MAF connected, and unplugging the MAF "cures" it, sort-of (it'll drop into limp-in mode without the MAF input, so it won't be running Right), then it's Probably a bad MAF.
The MAF itself, not the relays - A bad Power relay will usually result in a code with the MAF plugged in (because essentially it's the same thing as unplugging the MAF), and a bad Burn-off relay doesn't effect the way it Runs (not at first, anyhow).
Replace the MAF. Borrow one from a friend, if you can, to prove it first.
The TPS is a different deal. If the New one causes the car to not start, then either it's Bad, the connector to it is bad, or you haven't adjusted it.
If it won't respond to throttle with the MAF connected, and unplugging the MAF "cures" it, sort-of (it'll drop into limp-in mode without the MAF input, so it won't be running Right), then it's Probably a bad MAF.
The MAF itself, not the relays - A bad Power relay will usually result in a code with the MAF plugged in (because essentially it's the same thing as unplugging the MAF), and a bad Burn-off relay doesn't effect the way it Runs (not at first, anyhow).
Replace the MAF. Borrow one from a friend, if you can, to prove it first.
The TPS is a different deal. If the New one causes the car to not start, then either it's Bad, the connector to it is bad, or you haven't adjusted it.
Thread Starter
Advanced
Joined: Oct 2007
Posts: 50
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From: Durant Ok
After you replaced the TPS, did you calibrate it to .54 volts at idle ??
https://www.corvetteforum.com/techti...D=55&TopicID=2
https://www.corvetteforum.com/techti...D=55&TopicID=2
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Safety Car
Joined: Oct 2007
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From: :45 minutes from everywhere / E-I-E-I-O
I was needing some help figuring out what is wrong with my car. The car is an 86 4+3. After it messed up and we got it home, I started it up to put it in the garage, anyways when I started it up it would idle but any throttle input would result in it stalling out or dying. We finally got it into the shop and I was messing around and unplugged the MAF and the TPS, after doing this the car will idle, and you can rev it up, it is running very rich now though. If you plug either the MAF or TPS back in it results in it stalling and dying. We tried replacing the computer but that didnt change anything, but when we were changing out the computer we discovered that the car had a Hypertech chip in it. Do you guys think that it might be the chip, or should I look elsewhere? Any input would be appreciated.
Intermediate
Joined: May 2008
Posts: 36
Likes: 0
From: Katy TX
Have you checked your fuel pressure at the fuel rail? An almost dead fuel pump, or blocked fuel filter can get you enough fuel to idle the engine, but will cause the engine to die at anything more than idle.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I would disconnect the neg cable on the battery and let the ECM reset. Reconnect and try and start the engine. If it will not start..it's time to check fuel, spark, codes. Even this far into it, it sounds like it could be fuel related.
