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HELP! Need help on this one!


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polmec
New User

Dec 25, 2010, 11:44 AM

Post #1 of 9 (1509 views)
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I have a 1991 Camaro 3.1L V6 automatic with 131,000 miles on it. The car was running fine when I purchased it from a private party a couple of weeks or so ago. It drove fine for a few days. Then as we were driving one day it all of a sudden quit for no apparent reason. It restarted and ran for about 2 miles then quit again and we had to have it towed home.

Now it starts, idles very very low and the instant you open the throttle it dies. If I disconnect the charging wire from the alternator or the battery wire at the alternator or the battery when the car is idling, the idle seems to correct itself but still dies when you touch the throttle. When any of those things are plugged back in, it barely idles.

I have replaced the fuel pump, all the distributor components, coil, checked the timing, had the alternator checked, spark plugs are good, battery is good - I even tried another battery thinking something was wrong with the battery. Checked the fuel pressure which is 43 PSI, I pinched the fuel and the return line one at a time as the car was poorly idling and there was no difference. Changed the map sensor, unplugged the computer and checked the connnections which all looked good. There are no codes. When I pull the wires off of an injector, that cylinder dies. All fuses have been checked and are ok. It seems like the fuel injectors aren't getting enough voltage to fire correctly. Checked all the vacuum lines.

Done everything I know to do and still can't seem to find the problem. I have been a mechanic for almost 40 years and have never come across this problem before - challenging to say the least - I'm stuck!

Does anyone have any ideas????

Thank you very much for your ideas and thoughts on this. Would love to get this car running ASAP.

Polmec


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 25, 2010, 11:58 AM

Post #2 of 9 (1504 views)
Re: HELP! Need help on this one! Sign In

Do you have a scan tool? We need to see some datastream info during the problem.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



polmec
New User

Dec 25, 2010, 1:14 PM

Post #3 of 9 (1498 views)
Re: HELP! Need help on this one! Sign In

the car wont run long enough to get any readings


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 25, 2010, 1:16 PM

Post #4 of 9 (1494 views)
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Then find out if it's fuel pressure, spark or injector pulse that your losing.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



polmec
New User

Dec 25, 2010, 1:24 PM

Post #5 of 9 (1488 views)
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fuel pressure is good 42 psi,installed new pump,spark is good,rebuilt dist. w/all new parts,new coil plugs have good spark I believe its puls width due to voltage? As soon as the battery is taken out of the equation,battery,battery charge wires at alt.,batt wire at alt. the idle gets better but wont rev up,as soon as the throttle is open it dies. Plug battery back in and idle is rotten again.
Thanks


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 25, 2010, 1:27 PM

Post #6 of 9 (1486 views)
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It doesn't matter how many parts you've already thrown at it. You somehow need to determine what function your losing. If you can't do that, then all you are left with is the crystal ball method.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



polmec
New User

Dec 25, 2010, 1:32 PM

Post #7 of 9 (1482 views)
Re: HELP! Need help on this one! Sign In

I understand that, but what I cant figure out is why does it run idle better when the battery is taken out of the equation and then is bad when brought back in?


Sidom
Veteran / Moderator
Sidom profile image

Dec 26, 2010, 6:41 PM

Post #8 of 9 (1470 views)
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I would probably what to verify the mechanical condition of the engine before I moved on to any other areas.

Comp test, cranking & running vac, etc.

If all that checks out looking at a datastream with the KOEO & running could be helpful.

One thing I would really caution against and that is removing the battery from the system while the car is running. I can't tell you how bad of idea that is. Basically part of the battery's job is to absorb any surges or spikes in the system. With it out of the loop any little hiccup an you will be looking at a new PCM.


chickenhouse
Enthusiast

Dec 27, 2010, 9:18 AM

Post #9 of 9 (1461 views)
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Without any better info, I would be looking at vacuum and leaks.






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