White smoke at idle. Occasional misfire.

[smokin6.4]

I have an 08 6.4. This seems to only occur when it is colder outside. About a year ago when I bought the truck it started to do it. At first start while cold outside my truck will occasionally smoke white/blue fairly heavily. It will usually lead into a missfire on cylinder 5. Codes are cylinder 5 misfire and something about contribution. Dealer replaced injector and harness. It has done it once to me this year. I now have a dpf delete sct tune and afe. It has still done it since then. You can shut the truck off and restart and will run fine. Only does it at idle. Any help?

[dieselkane]

Are you losing coolant?

[smokin6.4]

Haven't noticed any coolant loss at all

[zach8z]

i have the exact same problem and when mine does it it sounds horrible like its misfiring on two cylinders it only does it every now and then and if u shut it off and restart it runs fine

[bluthndr]

One is in my shop doing that right now. #5 often/most of the time and #2 to a lesser extent on one of the 3 test drives today. Customer said it is losing a bit of coolant (externally) when he dropped it off - curious why someone else asked if that was happeneing - unless you are thinking head gasket?

No conclusions so far, but guessing it is an injector or two. It's here for head studs, a massive exhaust leak under the cab, and some other work, but I like to drive and scan everything before I ever go modding someone's truck... This was obvious from the moment I turned the key.

[WoodBoy]

Any more contribution codes OP or codes at all pulled with the sct? Also to the others, do yall have contribution codes?

[BIG RED BUBBA]

how white is the smoke? like is it a pure white or a light grey?

[bluthndr]

Originally Posted by WoodBoy

Any more contribution codes OP or codes at all pulled with the sct? Also to the others, do yall have contribution codes?

Yes, P0275 and P0305 both. I can watch #2 drop out a bit at times when cold on power balance, but not always. Only codes #5. Gonna check compression, but issue seems intermittent, so I doubt that's it.

[bluthndr]

UPDATE:

Bad news guys. Cyl #5 is 12% down on compression, so it's gotta come all the way down to see what happened. Gonna call him and see what he wants to do.

Strangely:

#6 is about 5% down on compression, but no miss and no codes.
All the fuel trims are right about the same - even #5 - except #7 which is +25 or so, yet #7 never misses and has fine compression.

A valvetrain problem in #5 could cause a bunch of stuff, but since it's not way, way down I bet it's more cylinder issue. Perhaps will will soon see...

[bluthndr]

UPDATE - #5 and #7 have crashed the piston into the intake valve, and the spray pattern on the #7 piston looks like F. Injectors and heads out for testing. Compression problem was bent intake valve on #5. No visible damage, but solvent pours right through the "closed" valve. Valvetrain looks fine - no idea what caused it yet.