In the winter the engine starts the first time every time, but it knocks and pings when I accelerate?

BILLY COLE

MEMBER
2000 CHEVROLET SILVERADO
5.3L
2WD
AUTOMATIC
270,000 MILES

Let me start by saying this has been going on for about 7 years. During the summer the engine runs really good although it doesn't start on the first try but it starts up on the second try no problem. I've changed the fuel pump and fuel filter and fuel line filter. I've changed the intake gaskets and knock sensors and I also changed the mass air flow sensor and put new plugs and wires on it. Now for the really weird part. When winter comes everything changes. It will now start the first time every time, but it knocks and pings when I accelerate. I tried all grades of fuel, and nothing helps. When summer hits it all changes again. I'm at my wit's end. Please help.

5 Replies

STEVE W.

MECHANIC
13,117 POSTS

Well, the description sounds like it could be a failing crank position sensor. They can get flakey with temperature swings, and they also help adjust the ignition timing. If you have access to a scan tool, I would plug it in, then watch the crank sensor signal live data. Now take one of the cans of "Dust Off" or similar canned air, flip it upside down and spray the sensor with the engine running. A good sensor won't show any changes, a bad one will throw a lot of changes. Be careful with the testing as you are spraying a refrigerant that can hurt you if you spray yourself. The crank sensor is located behind the starter, bolted to the block.

Image (Click to make bigger)