Five years approximately ago the engine was rebuilt because of a failed oil cooler. No expense was spared, whatever was required was carried out. Five years later cylinder 3 is misfiring when cold only, which soon clears. I'll upload files later, but I don't think WPS is showing anything. Although the third cylinder spark plug to me looks like its been burning coolant. Yes the coolant level had been topped up by the customer.
I'm asking if anyone has a good test plan to see if I can identify the cause inside the cylinder without dismantling? An HC check has not yet been carried out. Any advice much appreciated.
Edited to add additional information...
Turns out that what I thought was coolent entering the cylinder is not. Tests on the system show it is completely sealed. A test of the cylinder using the WPS shows a good 22" of vaccum acting. The spark plug thread was black and sticky when removed. The electrodes appear burned. The fault is not a leaking headgasket or coolant but defective valve stem seals with valve guide problems. It is oil entering the cylinder increasing the working temperature and burning the spark plug electrodes. What I have not yet got to the bottom of is why they have failed on a engine with 47K miles that was fully rebuilt five years ago!
Maybe I should go back to school, or call it a day I'm getting too old for all this I'm sure. Today the engine has started and run normal all day without misfires. valve stems and seals don't fail intermittently. So what the heck is going on with this cylinder 3? Scan tool live data shows nothing obvious along with no fault codes or pending codes.
Looking at the plug(s) what is most likely to cause the black plug and burned looking electrodes?
Does anyone know the typical current demand through the injector circuits? ThanksHistory...