A couple of weeks ago I had a coolant leak issue. Got a lot of help from several of you guys, thanks! Long story short - suspected crack in (plastic) intake manifold where the t-stat crossover pipe bolts up to it. Faced with the prospect of having to remove the alternator, fuel rails, COPs, etc, I opted to try the easy way out - at least for a temp fix. With my garage hovering about 120 degrees, I poured a $4 bottle of Barr's stop leak into the coolant system, and so far, so good. Two weeks without losing an ounce of coolant. I'm keeping an eye on it, and if it leaks again I'll pull the trigger on the permanent repair (side note - need to find an aluminum intake - why put another plastic one on there?).

So now, I've got a new proplem, think it's probably related. When the engine's cold, it runs fine, no problem. After about 20-30 minutes, it starts misssing, and I get a P0304 code - missing on #4.

Now, I can understand why that would happen when I had the leak - the coolant runnig down the head and into the coil extension/spark plug hole - shorting and causing the miss. What I don't get is why does this not happen immediately? Why only after it warms up?

Thanks all!

 

I don't really know either. Mine used to fo that to after a little water would get down the plug holes. My only guess is that once the truck warms up, it evaporates some of the coolant and it coats the boot, making the connection between the coil and the head via the water.

Just a guess. Clean out your plug wells and use lots of Di-electric grease and you should be fine.

 

The misfire may have damaged the COP. When your enging heats up the coil also heats which causes more resistance and can cause the coil to misfire. Try swapping the coil and see if the misfire follows the coil.

 

Very good tip on swapping the COP, thanks!

 

Yeah 2 of my COP's had to be replaced after it happened a couple of times. Then I finally wised up and mad sure the COP boot sealed properly at the top of the plug well.