Rough idle and popping sounds from exhaust upon sudden acceleration with poor to no response?

CACIQUE12

MEMBER
1997 CHEVROLET SILVERADO
5.7L
V8
2WD
AUTOMATIC
458,000 MILES

The truck listed above is a 2500. The initial issue was bad brake booster, replaced and now this! Used OBD on it and no codes. No Check Engine Light. Replaced the followings; fuel pump, in-line fuel filter, 4 ea. O2 sensors, MAP, IPS, TPS, plugs, fuel pressure regulator, PCV valve, cleaned throttle body, cleaned EGR, NO vacuum leaks found, no bad fuel, no misfiring. Please someone help me with this puzzle. Please someone help me with this.

6 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,658 POSTS

This sounds like you may have a broken valve spring or a burnt exhaust valve. We should remove the spark plugs for inspection. The one that looks different will be the cylinder that is having the problem. Also, let's do a compression test, this can tell us a lot.

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

Please run this test and get back to me, you can rent a compression gauge for cheap at the auto parts store.

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Wednesday, November 9th, 2022 AT 11:36 AM

CACIQUE12

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4 POSTS

I'll let you know the results, and we go from there. Thank you very much.

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Thursday, November 10th, 2022 AT 9:15 PM

CACIQUE12

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4 POSTS

Ken L,

Did both, compression test and the fuel pressure test? Before are the results:
A) compression test:
#2- 165 psi. #5- 160 PSI.
#8- 160 psi. #7- 165 PSI.
#4- 165 psi. #3- 165 PSI
#6- 165 psi. #1- 170 PSI.

B) fuel pressure was 60 PSI.

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Friday, November 11th, 2022 AT 5:50 PM

KEN L

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47,658 POSTS

Those are good readings, when the spark plugs were out how did they look, did you install new ones? Also, in the first post you said you replaced the MAP sensor did you mean MAF sensor? Also, is there a slight ticking noise in the engine when idling? Check out the images. (Below)

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Saturday, November 12th, 2022 AT 9:43 AM

CACIQUE12

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4 POSTS

I cleaned that one, MAF sensor. But replaced the MAP sensor which is the one next to the vacuum hose on top of manifold. The one that connects to the booster. Yes, I replaced all 8 plugs as well. No ticking sound, just a few popping sounds from the exhaust.