Thread: multi missfire when restarted warm

97 3.8 104,000

When vehicle is started after engine is warm i get a multicylinder missfire that remains untill engine is reved through a power cycle.

Check plug wires and routing ok they were replaced at 64,000.
I am leaning toward ignition module but dont have acces to a flow chart mitchell etc to figure it out.

Thanks

Which cylinders are misfiring? Could be a bad coil, or possibly the ICM that sits under the coils.


Jay

I think I am having the same problem. Run the car until it reaches normal temp, shut it off for 5 - 10 min and it misses on restart. Blip the throttle a few times and it clears out. I am thinking small headgasket leak - when the engine is hot the cooling system is pressurized, shut the engine off and anti freeze leaks into the cylinder keeping the cylinder from firing until it is cleared out. I am losing coolant at a very slow pace. I have replaced the LIM gaskets and upper intake manifold previously and think I am good there. Don't know just a thought.

Do you get a CEL when it misfires?

Does your oil look milky at all? If you suspect a HG, then I would do a compression test and see if you have a cylinder leaking.

Are there no other visible signs of coolant leaks? Check the coolant elbows. Also look for any trails of evaporated coolant around the waterpump area. Might be seeping out of the weep hole.

What condition are your hoses in?

I had a misterious leak similar to yours and all of the sudden my heater core let go. Not saying this is your issue, but just something else to consider. If you exhaust all other possibilities, try bypassing the heater core and see if the coolant leak stops.

Also, check the rad. for leaks. Mine was leaking at the upper hose neck as the plastic had cracked and would only leak when hot.

Jay

The logic behind the headgasket is there but i dont see it causing a MULTI cylinder missfire. Ill comp check it to verify.

thanks

We used to see a lot of leaking fuel pressure regulators cause that on the older models

Pull off the vacum line and see if its wet