Immensely rough idle
Hello there,
My GTI has a very very rough idle
It idles at 300-400 rpms and it shakes, jerks, studders, sputters, has a misfiring sound, and a glunking sound
I’ve been on just about every vw and Audi forum about this topic and the common response were to replace coilpacks and spark plugs, replace PCV valve, check an clean the maf.
I did all of that. With the addition of cleaning the MAP and air intake temp sensor to look like new. It did nothing
Then I took it to the shop I always take it to and they claimed to run a VAGCOM on it and got nothing, scanned the ecu and found nothing, resetted the computer, cleaned and readjusted the throttle body, and reset the idle control. All of that did nothing
Then when I got it back, I did a vacuum leak test, the kind where you take carb cleaner and spray it on suspected lines while running. Still got nothing.
I’m leaning towards a bad o2 sensor and/or a another blown PCV valve. But I truly have no idea
I really don’t want to take it to a dealer cause it’ll break the bank, but I might have to and I plan on taking it over there Monday if I can’t get a lead.
The car is a 2008 Vw golf GTI with the 2.0 FSI engine
113000 miles on the clock
Only uses 93 shell gas
Oil changes every 3000 miles ( only 400 miles since last )
I never go pass 3000 rpms on shifts
So please, anything can help.
Thanks!
Comments
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Idle air control valve is possible
Sad part is, these cars don’t have an idle air control valves. Only the diesels do.
It’s all electronic, which was resetted
Just as a shot in the dark get out on the highway and get closer to red line,
my subaru had a problem kinda like that a couple highway runsccleared it right up was told it was carbon build up on valves ant the high rpms help i guess
Hmm, didn’t think of that
Should I throw some seafoam in there too ? For added help?
Maybe this is the problem, VW Turbo engines are quite notorious for having valve carbon build up and short-shifting is not helping matters. Also checking the inyectors would be good, maybe they are dirty or they are not pulsating properly.
I would have to agree with Joseph. Since you’ve narrowed down so many options, carbon build up is very likely especially for those FSI and TSI motors. My dad had always told me to rev out my engine once in a while and this might be why. I know Mk6 GTIs need a carbon buildup cleaning after a number of miles. I heard that using seafoam is recommended every 10k to have less build up. Here is a picture of a Mk5 GTI with 70k miles and its buildup.
Yeah that’s what it seems like
Imma it rev it out next time I go driving and just see what happens
Then call my shop and see how much a carbon cleaning will cost.
Or do you recommend going to a dealer for that?
You can either do a short test of spirited driving or have VW do a diagnostic to look for buildup. Up to you. There are some videos on DIY cleaning, but I wouldn’t know how effective it is… I drive a Mk4 lol.
I’ve seen the DIY videos with using mineral water or seafoam or whatever and they don’t seem at effective.
I’d rather get them professionally done and get them manually scrubbed