1995 GMC Jimmy engine serges when idleing and while driving

Tiny
THOMAS BALDWIN
  • MEMBER
  • 1995 GMC JIMMY
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 198,200 MILES
I have changed the alternator, battery, motor, distributor, distributor cap, rotor, fuel pump, fuel pressure regulator, spark plug wires, spark plugs, radiator, thermostat, fan belt. The jimmy surges while running. Lately when the engine has warmed up and when I turn it off, it will not restart, but if I take one of the spark plug wires off, it will start. Before it died and left me stranded on the road I had it towed to a garage and the mechanic can not seem to get to the bottom of the problem. No dash lights come on to inform me of any problem. What should I try next? The distributor came with a module, and now I think it is the computer but the mechanic says it does not show any codes to chech, he state
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Tuesday, September 14th, 2010 AT 9:23 AM

5 Replies

Tiny
HMAC300
  • EXPERT
Check two things, if you have a crank sensor-it's in the timing cover, check the ohms as they can be to high and cause the problem. Then get some choke cleaner and clean tthe throttle plate on both sides along with the oblong hole on it. It will be hard to start after doing this, but it gets oily and causes some of the problems you are experiencing.
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Wednesday, September 15th, 2010 AT 6:02 PM
Tiny
THOMAS BALDWIN
  • MEMBER
I think we have found the problem. We replaced the pigtail going to the fuel injector. It was loose on the two prongs sticking up. Now it seems to be hitting on all cylinders but service eng. Soon comes on and does not want to down shift when it gets hot, and idles rough. Could the next problem be in the temperature sensor or the oxygen sensor? All the fuze checked out ok.
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Thursday, September 30th, 2010 AT 7:52 PM
Tiny
HMAC300
  • EXPERT
Sensor like 02 and coolant normally don't do that, but if your service engine light is on have it scanned and see what is setting the code, that could be your problem. YOu have to eliminate codes first for other problems. The downshifting may be a trans problem or a bad connection as well. You will need a pro model or a trans guy to look at the downshifting problem. But get the service engine light out first.
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Friday, October 1st, 2010 AT 9:06 AM
Tiny
THOMAS BALDWIN
  • MEMBER
Most of the surging and not shifting was solved with a change of the computer and now it shifts good and runs fairly well with a slight movement of the engine while idleing. No dash lights are on to indicate trouble though. Could a computer diagnosis show any thing else with on truble light?
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Thursday, October 7th, 2010 AT 2:31 PM
Tiny
HMAC300
  • EXPERT
For your shifting problem take ti to a trans pro and let him see if he can see anyhting going on. He migh thave to try to freeze frame to find the problem. But it can be a connection on the trans as well.
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Thursday, October 7th, 2010 AT 7:39 PM

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