Engine lopes while idling and lack of power

ALFREDES

MEMBER
1988 GMC VAN
5.7L
V8
AUTOMATIC
100,000 MILES

My vehicle just recently started running rough while idling. Sputters, coughs when trying to accelerate. Replaced EGR valve, o2 sensor, distributor cap, rotor, spark plugs, and fuel filter. Problem still continues. What could the problem be?

Thursday, June 30th, 2016 AT 6:32 PM

4 Replies

JACOBANDNICKOLAS

MECHANIC
108,192 POSTS

The idle issue is usually the result of a bad idle air control valve, IAC. The IAC is responsible for maintaining a smooth idle. However, the acceleration is different. Are you sure the fuel pump pressure is within the manufacturer's specs?

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Thursday, June 30th, 2016 AT 7:42 PM

JACOBANDNICKOLAS

MECHANIC
108,192 POSTS

Other thought. Have you confirmed the catalytic converters are not plugged?

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Thursday, June 30th, 2016 AT 7:43 PM

ALFREDES

MEMBER
3 POSTS

Still having problems replaced distributor advanced timing emptied beads out of plug in catalytic converter and swapped out fuel meter body

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Tuesday, July 5th, 2016 AT 6:28 PM

KEN L

MASTER CERTIFIED MECHANIC
42,904 POSTS

I would do an compression test, it sounds like you may have a broken valve spring.

Here is a guide to do the compression test.

https://www.2carpros.com/articles/how-to-test-engine-compression

Let us know what you find

Best, Ken

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Wednesday, July 6th, 2016 AT 8:26 PM