A while ago had a misfire, and changed the switching module. Things seemed to work fine for a while but last week I had a misfire again. Had it checked out and the dealer claimed it was due to carbon build up on the valves. Is this normal on a '99 1.8T Passat with 80k miles? Can I adjust my driving to slow down carbon buildup? and Do the fuel additives work to remove the buildup? (and which ones are the best)
Thanks!
Forgot to say that the misfires only happens when the engine is cold, but definitely not every time the engine is cold.
Carbon build up on valves is caused by "gas quality" so changing brands and looking for gas that has fuel cleaners should help prevent the problem. In our area, we must be lucky with gas because it doesn't seem to be a problem even with car over 100,000 miles. The problem we see is that owners don't change their timing belt and it breaks! That how I know there is no carbon problems in our area as I get to inspect the bent valves during the repair.
As for cleaning your carbon off at this point check to see if you can find a place that injects the cleaner into the injectors. We have an unit that we disconnect the fuel lines so the cleaner goes directly into the injectors so the injectors and valves get 100% cleaner and the car runs for about 10 minutes on the stuff.
I understand that carbon build up can also be an indicator of a cool running engine. Maybe someone chose to use a cooler thermostat thinking it would be good for the engine, or the thermostat is bad.
True, but the newer cars monitor coolant temperature and the MIL would set if engine isn't within the operating range. I think if it runs about 15 cooler that's enough to turn the MIL on.
Thanks for the advice!
The temperature gauge is always steady at 190 (after a few minutes of driving). Allthough this won't always be the real engine temp, there shouldn't be a problem here.
Having the engine cleaned through the injectors is about $200, I can buy a lot of bottles RxP for that and throw that in my gas tank. Will that work too, or is this a waste of money?
My fix is always a bottle of slick 50 fuel system cleaner(9 dollars at autozone), a tank of premium gas, and a lap around 465 (50 miles), or trip of equal distance. Has always cleared up issues for me.
-Larry
Premium should have no effect. The quality of the fuel can.
I'll give the slick 50 and always fill up premium, maybe I shouldn't fill up at the cheapy place. Problem doesn't occur too often, but hopefully it brings the frequency down. I understand that a misfire isn't good for engine and cat, but how bad is a few misfires a week? Does that need immediate attention or can I try for a few weeks and see how that goes?
Thanks!
Drove over three hundred miles yesterday; Colima and back to the Bay Area, with a few miles at pit stops it was all freeway.
Car ran 75 mph with three folks and a bunch of luggage on the way up and
80 mph with just the two of us.Man, car was peppy, peppy, peppy after that. (Toyota Cresida with inline six cylinder motor).
Should apply to VWs as well, might help to add some B12 Chem tool of Chevron Techroline (Slick 50 _cleaner_ might be OK) they are pretty much the same volitle aromatic hydrocarbon solvents.
Do a goggle search for
+"Italian Tune Up" .TBerk
I should add that premium where specified by the manufacture does make a difference and should be used for several reasons, but it will not help reduce or prevent carbon deposits.
Atleast this explains the carbon buildup, my wife never drives it over 3k rpm, I'll make it a decent Italian tune up, with some chemicals and see how long that lasts.
Do a Google search on GM Top Engine Cleaner. I woud have tried it on my old 78 rabbit but I'm not sure I'd use it on a modern engine.
Bill
78 Rabbit...10/77 - 4/02 82 Convertibles(s)...since 93 95 Golf GL...since 11/99 02 Passat 1.8T Tip GLS...since 4/02 (Remove the CAT to email me)MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.