Roaming revs at idle

[grmair]

My Mk 5 GTI has started revving very randomly.  At idle the revs sit at about 1200 then rise to 2000 or 3000 over a few seconds, then returns to about 1200.  I can't be sure but it feels like it's lost some power too.  Any suggestions where to start looking would be appreciated.

[Komenda]

One or more of the coil packs could be on their way out.

[grmair]

Thanks Komenda,

It's a long story but i have had problems with them before. I had over-spec'd plugs in and they were burning out the coils.  It's possible that one was damaged at the time i sorted the plugs out and is only now showing the signs after degrading over time.  Is there a simple way to test the coils for damage? As far as i know they're packaged pretty tight. This one's a real annoyance!

[bacillus]

Thanks Komenda,

I had over-spec'd plugs in and they were burning out the coils. 

What type of plugs??

[grmair]

I put Denso Iridium's in.  They claimed to be suitable but they burned at too high temperature and blah blah blah.  I replaced it with proper standard Bosch Platinums and all was fixed.  All i can think of is if you're right, one of the coils was still damaged but has got worse over time.  Maybe it's that or maybe it's a completely new problem.  I'm scratching my head at the minute...

[bacillus]

hmm, are you saying that your car idles at 1200rpm when warm?

[Riz]

what was the Fix? i think i have coils

[DanoGTI]

Just to add to the mix - fwiw, I had the same type of issue with my Scooby.
The MAF (Mass Air Flow) sensor was dirty/failing. Caused the performance to drop off (BIG time) and also the idling was erratic.

Personally, I'd still go the coilpacks, but it might be worth checking the MAF out too

HTH & "good luck"

Dan