So I have a MY06 and am having two seperate idling issues, they may be directly related, or may not be

1) Intermittent rough idle - most of the time when I'm idling it feels normal/semi-normal. Occassionally it feels like someone swapped v8 with cams and open pipes

2) More often than not when coming up to a stop, and I clutch out and approach a stop, the rpm's will jump up to about 500 (to ~1400) and it has that 'floating feel'.

So my complete lack of automotive troubleshooting knowledge, leads me to believe problem #2 may be related to a vaccuum leak and/or a IACV issue (do we have a IACV or something similar)? Which vacuum lines/items outside of the engine should I inspect that are related to idling? Issue #1 leads me to believe I should get a leakdown test (and subsequent testing/repairs based upon that), however I won't be able to do that for another 3 weeks until I have some days off, as I'm working graveyards and the S is my only ride. The car drives fine, it's only the idle that's being affected.

Appreciate the tips

 

Nothing?

 

run to part store and get an start up helper spray. and spray an small amount near any vacuum line. if rpm goes up. u have a leak there! takes like 2 mins.

 

Clean the IAC valave and throttle body plate area like i did with a good carb cleaner.Really improved my idle which was shaky and caused the car to shudder. Look in the DIY thread for insturctions on cleaning the IAC valave. Its very easy...

 

There is no IAC valve on DBW cars, idle is controlled by the DBW throttle.

Do not spray anything into the DBW throttle body.

Use a dry rag and wipe it if you like.

 

Ended up being much worse. Took it in to the shop today. My compression test showed 160 and 160 on cylinder 1&2, and 105 and 105 on 3/4. Only 5% loss on 1&2, 30% loss on 3/4. Intake valves on 3 are screwed, exhaust valves on 4 are screwed. Car's gonna be down a week for head work to be done. I'm just praying my aftermarket warranty won't deny me.

Appreciate some of the pointers though guys

 

Most of all, its important to find the underlying cause of why the valves are bent. I would make sure the guides a thoroughly inspected.

It is near impossible to mechanically over-rev/mis-shift an AP2, ESPECIALLY high enough to bend valves. it would require you to go from third gear to first while wide open. Or fifth to third. Impossible.

 

ouch sorry to hear man, did you misshift recently?

 

I'm thinking, it might be a case of my lack of pro-active action when I first felt the idle get bad. Not entirely sure where it could have come from, though once this is taken care of, I'll definitely be asking for their insight. It's the best shop in this town, so I have no doubt they'll make sure everythings in tip top shape. Though I'll find a way to mention the guides, without insinuating that they wouldn't have checked them otherwise.

Nope, no misshift. There was no event that caused this catalyst of events, or at least, nothing that I did (perhaps something that I didn't do?).

On an unrelated note: Graciously, my parents are letting me use their SLK to get to my graveyard shift while their asleep. There's more sport in half of a OEM Miata tire, than in the entire SLK.