HELP! Need help on this one!

Tiny
POLMEC
  • MEMBER
  • 1991 CHEVROLET CAMARO
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 131,000 MILES
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
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Saturday, December 25th, 2010 AT 6:49 PM

9 Replies

Tiny
JDL
  • EXPERT
Check the o2 sensor reading, maybe you can see if running lean or rich. Do ohms test on injector bank, compare one bank to the other. Engine idleing, you can also compare map sensor signal to tps senor signal. They should be close to same reading, not exact.
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Saturday, December 25th, 2010 AT 7:01 PM
Tiny
POLMEC
  • MEMBER
The engine wont idle long enough to check those things. As soon as the battery system, battery, battery lead@alt, charge wires on alt, is taken out of the loop(disconnected)the idle seems to be better but when batt. System is reconnected car barely idles momentarily and then usually dies. As soon as the throttle is cracked, at just about anytime the car dies instantly. Carb spray helps a little on throttle up but not much. Car has a new cat. Conv.
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Saturday, December 25th, 2010 AT 7:22 PM
Tiny
JDL
  • EXPERT
Doesn't have to run to do ohms test on injector bank. You do that test with everything turned off, no voltage, no ground.
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Saturday, December 25th, 2010 AT 7:34 PM
Tiny
POLMEC
  • MEMBER
Just checked ohms @# injectors .02 manual says 8-12 @ 140deg.F
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Saturday, December 25th, 2010 AT 8:03 PM
Tiny
JDL
  • EXPERT
With mfi, injector ohms is probably around 12 ohms, one injector. I can't see what your doing? That spec you listed isn't right, 02? Most of the guys I talk to say, they don't want to see any injector under 11 ohms.
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Saturday, December 25th, 2010 AT 9:02 PM
Tiny
POLMEC
  • MEMBER
I put the meter on ohms and measured right on the injector
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Saturday, December 25th, 2010 AT 9:25 PM
Tiny
JDL
  • EXPERT
The injector is faulty according to that reading. The less resistance the higher the amp draw, too high an amp draw, the computer may shut down the injector driver. If possible do an ohms test for one injector bank, that means all three injectors at the same time. If one injector ohms spec is 12 ohms, you divide by 3, the number of injectors in a bank. The reading should not be less than 4 ohms, for the bank. That's the way I learned to do it.
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Sunday, December 26th, 2010 AT 3:51 PM
Tiny
POLMEC
  • MEMBER
Sorry injectors check @ 13-14 ohms I had the meter set wrong
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Sunday, December 26th, 2010 AT 10:36 PM
Tiny
JDL
  • EXPERT
Did you check all injectors? Use a noid lite, check for injector pulse?
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Monday, December 27th, 2010 AT 3:58 PM

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