Okay, so two days ago the engine light on my 02' 4.7 with 161,600 miles came on, I checked it and it was p0300. Easy enough, multiple cylinder misfire. The next day I noticed that the truck was running really rough almost sounds like not all cylinders are firing and at times was even hard to start like the engine was kicking back. Also I noticed ALOT of white smoke from the exhaust for just a few minutes then it seemed to clear up. Today I noticed that the day tank was almost empty, had to put in a whole gallon of water and my oil was a little low, wasn't to worried about the oil because the truck does burn oil and I am about 700 over on oil change. But what grabbed me was when I went to add oil there was a white residue on the bottom of the oil fill cap. I know about engines, I am a diesel mechanic by trade but all of this happening at once is kind of throwing me. If anyone can please help I would appreciate it. On a side note, I put new plugs in it about 6 months ago and changed 1 coil pack that was bad.

 

Sounds like you may have a blown head gasket. Do a compression test to make sure.

 

I will try and check compression this weekend. I have seen a blown gasket put oil in water, water in oil and compression blow coolant out of tank but can it throw codes and make misfire?

 

if antifreeze is entering the cylinder... there is your miss-fire.

white foam on oil cap.. is moisture mixed with oil. pcv valve maybe bad OR engine is not getting to 200 degrees...

 

I knew that the white buildup was oil/water mixed but my engine oil looks like brand new, not milky at all. My radiator has a slow leak and I know where it is I just haven't had the time to change it yet. Well it looks as if the "engine fairy" came and fixed my truck over night. Started her up this morning for work and the engine light was off and she didn't miss at all. Drove about 200 miles today and it was like normal. I had gotten gas the night before all this started, I'm wondering if I had gotten some bad gas at the shell station. I only put in 8 gallons and yesterday I topped her off with gas from a different station. Will post if anything else happens. Thanks for all the help.

 

Its possible to get bad fuel. Although most places sell enough so you usually doesn't happen. Try running some sea foam. I would still do the compression check. When was its last tune up?

 

Never had a chance to do compression check because of work. I bought the truck about 9 months ago and right after I got a code p0302 i think, changed that cylinders coil pack and ALL plugs with a set of copper classic split fires that the previous owner had bought but never installed. Haven't had a problem since till this started. i change oil about every 3500 with Mobil one full syn. The code never came back but I noticed yesterday that it was still white smoking a little and it had power but the exhaust didn't sound like it usually does. Have flowmasters on it and you can def hear a differance. I changed the pcv valve earlier today, it had a little bit of moisture in it like the oil fill cap did but still no milky oil, it's as clean as when I put it in. I need to get a compression tool for the truck, all I have is for detroits, John Deere and cummins. But that's what I work on.

 

Pull the valve covers and see which rocker arm came off. Hopefully the valve isn't stuck down or broken. Stop running the engine though.


The code isn't going to come back no matter how bad it misfires, since you erased the memory. The misfire monitor won't count until the Adaptive Numerator is relearned.