Missfire, Carbon. GDI
This is a GDI engine, 115K, with what looks like a lot of
carbon build up. My experience so far with GDI is this is
normal. We started with Misfire, P0300, on all cylinders.
Engine runs rough at idle, Vacuum is 15" at idle. WPS shows
VE is compromised, but not showing a fully burned valve. (
Recently did a Mazda Turbo GDI with a valve cut in half. )
We did a aggressive FI service with BG, even pulled the
intake and soaked it. Interesting thing is, we fixed one
bank. Good trims, no miss showing on bank 2. We got the VE,
and trims to settle down on bank 1, but not all the way. The
most interesting thing is, driving, it runs good, trims at
+6, or under. It will not show misfire, or set code for it,
unless you are decelerating. Vacuum is still low, 16.5", and
WPS is better, but still jumpy. I pulled the valve cover
just to see in the cam. Looks OK. Probe pictures from exh.
side show a lot of buildup on the exh. stem. I believe the
Valve guides/stems are worn, causing the issue that remains,
and we are doing a valve job.
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2010 Buick LaCrosse CXL 3.0L