2002 Chevy Venture

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. No kidding! Does anyone have and suggestions as to the problem?

 

Im guessing your code is PO 301......?

Look carefully at your ignition wires. A " Spray Bottle" directed at the passenger side back corner of the engine will likely reveal a bad wire. If you look under the hood first start of the day, look and listen for "SPARK -ARC".....

Any engine work done recently???...Battery been disconnected , or dead lately? Its rare , but sometimes the PCM can lose its "SYNC", and fire opposing cylinders at the wrong times...which will produce a Misfire code in either #1 or #6...( If you look at the coil pack, you will notice 1 +6 are paired on the same coil).

 

Thanks for the comments unclediezel.

Autozone read the code and all they told me was number 1 cylinder misfire.

I assume the spray bottle is to mist water on the spark plug wires to see if there is an external spark jump from the wire to ground, but I figure that would have to be in the dark in order to see it very well. Not sure if I could hear or discern "spark-arc" over the engine noise.

I did have the thermostat replaced recently, but can't imagine what that would have to do with the misfire.

I get 87 meanings for PCM on Google including "please call me" so not sure what you mean.

The 6 year old van has 101,000 miles on it so I figure it is time for new wires and plugs minimum. I think I will scrub the floor mats too.

 

PCM....Powertrain control Module.....Engine computer...

 

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.

 

Possibility, but usually accompanied by a hard start , first start of the day.

If the fuel were to leak into a cylinder, it would also depressurize the fuel rail, requiring excessive cranking time to re-pressurize the fuel.

 

It has been determined that coolant is leaking into the cylinder overnight.

Going to pull the top off and rebuild it.

 

New head gaskets, trued heads, ground valves & valve seats, new valve stem seals, new intake manifold gaskets, new spark plugs, fixed exhaust manifold leak, new oil, new throttle position sensor...$1250. Runs like new.

And I also scrubbed the floor mats.