GMC Repair: Cold Engine Miss, spark plug wires, hydraulic lifter

Question
I have a gmc with a v6 1977 model pickup...when the motor is cold the engine will miss until it warms up. The rest of the day it runs smooth..only with it cold does it miss....I have changed the plug wires and plugs.

Answer
There are numerous possibilities. The most common that comes to mind is that you have a leaking hydraulic lifter (IF your vehicle has hydraulic lifters) whereas the check valve in the lifter is not sealing and the oil is draining out of the lifter over night thus causing a COLD MISS until the lifter refills with oil.

If you start pulling spark plug wires while the engine is missing can you determine which cylinder is at fault ?.

Pull the distributor cap OFF first thing in the morning and see if there is any moisture in the cap.

Is there ONE spark plug that is a different color at the electrode end as compared to the rest of the plugs ?.


let me know.


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