2004 Chevy Silverado wont idle

ASUPINGER1

MEMBER
2004 CHEVROLET SILVERADO
V8
4WD
AUTOMATIC
100,460 MILES

I was getting on the hiway and noticed a slight loss of power and acceleration unless I floored it then it was fine. When I stopped at the off ramp light it would not idle on its own. I can push the gas and it feels smooth over 2000 rpms. So ichanged the maf sensor, spark plugs, wires and even the catalytic converters. Still runs rough at low rpm and wont idle at all. But will start right back up. Can you help me. My check engine light is on and get codes P0300 and P0101. A garage checked it and said it was that cats. But it wasnt.

4 Replies

DENNYP

MECHANIC
1,823 POSTS

The first step would be cleaning the throttle body out. If you have carbon buildup in the throttle body, it will cause poor or no idle quality. If this doesn't help, try to determine which cylinders show misfires. Let me know what you find.

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Thursday, February 18th, 2021 AT 12:41 PM

ASUPINGER1

MEMBER
3 POSTS

I checked the engine compression and one cylinder had no compression at all so I removed the valve cover and that cylinder has a broken valve spring. The throttle body was fine.

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Thursday, February 18th, 2021 AT 12:41 PM

DENNYP

MECHANIC
1,823 POSTS

Was it the driver side rear cylinder? I have seen about 5 different silverados with broken valve springs in the same location. 4 of them just got valve springs, 1 of them had to get a cylinder head.

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Thursday, February 18th, 2021 AT 12:41 PM

ASUPINGER1

MEMBER
3 POSTS

It was the second cylinder from the front on the drivers side. And the rear spring on that cylinder. If you had heard of that before then a clue might of saved me alot of time and money.

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Thursday, February 18th, 2021 AT 12:42 PM