Misfire with no codes
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Misfire with no codes
I have a 98 Expy with 128k on it and it is having misfire issues with no CEL or codes pending. When the truck is cold it runs fine but after it warms up and is shut off the problem comes on restart. There is a obvious misfire when under load like when going up a hill. The truck won't rev and starts breaking up. Level road driving isn't bad.
The fuel pump and filter are new and the plugs are only a year old. Fuel pressure is 40 psi with vacuum off and scanner shows fuel trims are spot on. Coils are only 2 years old and I think that's the problem(not good quality). TPS was also changed. Truck has no vacuum leaks either. What could it be besides coils? I really don't want to buy another set just to find out that's not the problem
The fuel pump and filter are new and the plugs are only a year old. Fuel pressure is 40 psi with vacuum off and scanner shows fuel trims are spot on. Coils are only 2 years old and I think that's the problem(not good quality). TPS was also changed. Truck has no vacuum leaks either. What could it be besides coils? I really don't want to buy another set just to find out that's not the problem
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