Exhaust with no muffler or catalytic converter rides rough and sputters when accelerating

BIGJOHN01

MEMBER
1996 GMC SIERRA
5.7L
V8
4WD
AUTOMATIC
178,000 MILES

Truck rides rough and sputters when I get on the gas. After the truck gets hot, I can feel it clear up and drive better. Even the exhaust sounds better. Just had new exhaust pipes installed with no muffler.

Thursday, December 8th, 2016 AT 6:56 AM

5 Replies

HMAC300

MECHANIC
48,601 POSTS

Scan for codes and check fuel pressure with a gauge auto parts rent it. See link.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

also, check for a vacuum leak and soft vacuum hoses if soft replace them.

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Thursday, December 8th, 2016 AT 12:22 PM

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Hey Bigjohn

It sounds like it could be a mass air flow sensor that has gone bad or is dirty, also scan for trouble codes, here are a couple of guides to help you,

https://www.2carpros.com/articles/mass-air-flow-service

and

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please let us know happens so it will help others.

Best, Ken

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Monday, December 12th, 2016 AT 12:01 PM

BIGJOHN01

MEMBER
2 POSTS

I've put new plugs, wires, cap and rotor. Replaced mass air flow sensor. New fuel filter, fuel pressure regulator and injectors. My exhaust broke loose and had to fix it cheap. Got a feeling it's either the throttle position sensor or the O2sensors

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Monday, December 12th, 2016 AT 4:03 PM

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Do you have an OBD2 plug? Or is it an OBD1 truck?

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Monday, December 12th, 2016 AT 4:17 PM

HMAC300

MECHANIC
48,601 POSTS

Scan for codes that is one of the first things to do also check for a vacuum leak because it sounds like computer is richening the fuel mix to take care of vacuum leak also running with no cat and no secondary O2 is not a good idea.