WHY DOES CHEVY RUN FINE AT IDLE-BUT BACKFIRES, AND RUNS ROUGH WHILE DRIVING?

1997 Chevrolet Tahoe

Tiny

debohallo

February, 21, 2012 AT 12:20 AM

Cannot go over 20 mph or it will bog down and die out. We replaced the fuel filter, plugs, plug wires, and upper crank position sensor. We also had the ignition control module tested and it checked out good. We ran some seafoam through because water was coming out of exhaust. Nothing has made a difference-please tell me what to try next?

FOUND 4236 RELATED QUESTIONS

Running Rough

27 ANSWERS
34 IMAGES

Idles Rough/changed Ects

37 ANSWERS
3 IMAGES

12 Answers

Tiny

billymac

February, 21, 2012 AT 12:24 AM

Two possibilities fuel pump or timeing chain. I would check these both.

Tiny

debohallo

February, 21, 2012 AT 12:26 AM

Can you tell me how to check both?

Tiny

debohallo

February, 21, 2012 AT 12:27 AM

Because it runs well at idle I did not think fuel pump

Tiny

debohallo

February, 21, 2012 AT 12:31 AM

I just asked-and the fuel pressure was checked while the vehicle was running-and it was 60 lbs pressure

Tiny

billymac

February, 21, 2012 AT 12:32 AM

Yes but it requires less fuel delivery at idle when you accelerate more volume is required the bogg and backfire together really to me seems like fuel delivery prob. This is just something that should be checked not common for a fuel pump to act this way, but I have seen it.

Another possibility is a restricted exhaust system

Tiny

debohallo

February, 21, 2012 AT 1:00 AM

Do you think it could be the distributor cap?

Tiny

billymac

February, 21, 2012 AT 1:04 AM

Yes it is a possibility that the distributor cap or rotor has failed cracked I thought you had tuned it up sorry my mistake. So fuel pressure is ok now we have to believe it is electrical I would replace that cap and rotor so it can be eliminated.

Tiny

debohallo

February, 22, 2012 AT 12:05 AM

We did replace the rotor-not the distributor cap. Today we replaced the crank position sensor-the first one we replaced was the cam position sensor. It seems to have more power-but still backfires. There is a lot of condensation coming from the exhaust-even though we previously ran seafoam through it

Tiny

debohallo

February, 22, 2012 AT 12:07 AM

The code is P1345-which is cam sensor/crank sensor correlation-but both of the sensors are new

Tiny

billymac

February, 22, 2012 AT 12:35 AM

This sounds like a timeing chain. Olease repost your question and hopefully our gm guys can help

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