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2002 Chevy Venture

The van has 101,000 miles and recently when I start a cold engine, it runs rough for about 30 seconds and then always smooths out and runs fine. The computer code says Number 1 misfire. Does anyone have and suggestions as to the problem?

Has this car been checked for intake manifold coolant leaks?

I don’t have the exact date or mileage, but the intake manifold gasket was replaced once upon a time. There is no lose of coolant at this time. The thermostat was replaced recently to correct overheating.

A neighbor (certified master technician - ASE certified) thinks it could be a leaking fuel injector that overnight it leaks fuel into the cylinder causing the misfire until it eventually clears up. He says a bad plug or wire usually won’t clear up. He is going to look at it next week. Does anybody concur?

I concur that that’s a possible cause, however there are other possibilities including oil leaking down past a bad valve stem seal and fouling the chamber until it burns off. Also, a bad plug, overdue for change and with a resulting large gap, may not be firing well until the engine heats up a bit.

Besides, I’d expect a leaky injector to leak all the time, creating too rich a mixture in that cylinder and perhaps tripping a CEL. Remember that when the pump is running the line behind the injector is at full pressure.

I’d be inclined to wonder when the last plug and wire change was, put new plugs in, and “read” the old ones. I try to start with the basics first. I’m sure your neighbor would agree.

I had the same problem with a 1990 Ford Aerostar van. The van had the head gaskets replaced under warranty. I didn’t see the coolant drop, but apparently a little coolant was seeping into a cylinder. It ultimately turned out that the head gasket failed because of a cracked cylinder head, and the problem reoccured. By this time, enough coolant leaked into the cylinder to score the cyliner wall, so Ford replaced the entire engine under warranty.

As others suggest, your problem may not be as serious. The intake manifold gasket may be causing the problem or the fuel injector may be leaking down.

It has been determined that coolant is leaking into the cylinder. Going to pull the top off and rebuild it.