MDHLexus

iTrader: (5)

So I had a reoccurring p0304, and a few scattered p030x along with it. I pulled of the valve cover and saw that the valve heads were coated in carbon. I tried everything to clean them... seafoam, hot soak with Techron and scrub with wire brush, water decarbonization, and then finally went to the Lexus Stealership and let them clean it. I forced them to take before AND after pictures, and after looking at the pictures it was clear that none of my cleaning methods worked at all. The after pictures show shiny metal valves, but still a little bit of residual carbon pieces, since they just scrape it off they don't use chemicals anymore. I have been getting misfires still, and that procedure was done almost a month ago. The misfires are far less frequent, and all I have to do is pull over, turn the car off, wait 5 seconds, turn the car back on, and its good. And it is almost always when I'm coming to a stop. I can drive 200 miles on the freeway just fine with no traffic (I've done it 4/5 times now).

My question is, do you guys still think this is carbon build up? I can't see it being a coil or plug, because if it was it would have gone permanently bad already. I was thinking maybe it is carbon build up on the stems of the valves now, so that the valve stems are sticking when they slip up into the guides. Any thoughts, ideas, questions, comments, anything.... would be helpful.

Thanks in advance,
Matt

MDHLexus

iTrader: (5)

Here are some valve pics.

These are the pics Lexus took, before they scraped the valves. So this was how dirty they were even after all the seafoam, water, and techron.



These are the after pics, notice how there is some carbon still built up around the top most part of the stems.

Aspect

If I saw your problem earlier I'd have suggested getting a BMW shop to walnut blast your valves... just got mine done and they look way better than what you've posted. Maybe it's still misfiring because of the carbon buildup past the top parts like into the crank case IIRC.

trippy

iTrader: (1)

after reading this i took my 250 and WOT on the freeway twice lol damn carbon build up

i also took my ride to lexus to get it cleaned fine so far and i ran redline fuel cleaner and switch gas to shell

TopNotchIN

I own an '06 IS250 AWD and cleaned up some carbon deposits , shortly after purchase, when I changed my spark plugs. Well, after having the car awhile and adding more mileage there were idling issues. At stop lights there would be a slightly lumpy idle and sometimes I would get a misfire code. The car ran well and smooth for the most part. My experience with BMWs led me feel that treatments with P.E.A. could help since carbon buildup is an issue with those cars, too. I know it's speculation because of the direct injection though. I tried a once-a-year treatment from GUMOUT that claims to work with port AND direct injection. It was like $20 at Wal-mart, but I'm sure you could get it at any auto parts store. It seems to have helped out. You add it to an empty tank and then completely fill up with gas. I'm not sure what or it if did anything, but it did seem to burn off the carbon deposits. Sometimes I would go WOT to help out and the exhaust would definitely smell burnt like it was working. YES, I know for a fact it wasn't burning oil out the exhaust.

MDHLexus

iTrader: (5)

Thanks for the info, maybe i'll try some of that product as well. I don't understand how it would help the intake valves though? Like, just thinking out loud... if you pour that into the gas tank and we have direct injection, wouldn't it only get the exhaust valves and inside the cylinders?