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Q: Car misses

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The car misses even the the compression and leak-down test are good.

If you have went as far to do compression and leak down, I’ll assume the problem is not obvious. After those tests, you can be almost sure the mechanical components of the engine are good. Is it a random misfire or one cylinder? Some problems that would affect all would be a bad ignition coil. Spray a mist of water to check for voltage leaks. Load the coil by pulling a wire ½ off a plug. Carefully inspect the distributor cap for carbon tracking. Check each plug for the same. Crankshaft position sensors are common to fail completely on these engines, however, sometimes they will put out a “noisy” signal to the PCM. Check it with a lab scope. I would also perform an injector balance test. Finally, check fuel pressure, vacuum leaks, or clogged exhaust. If you need assistance, a qualified mechanic from YourMechanic can come out and diagnose your car’s misfiring issue.

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