After much b*tching about driving my car in traffic I have to wonder if the whole issue is my idle. The car seems to need excessive nursing of the throttle to keep it happy, and obviously this becomes an annoyance in stop and go traffic.

I honestly thought nothing of it at first, just figured it was the nature of the vehicle. But I hear the coupe should be idling around 600.

Mine seems to be a fairly consistent around 400rpm.

I assume this all stems from repairs my car had before I bought it. (it was in a supposedly light front/passenger side accident. With all damaged parts being replaced with new oem stuff. The full extent of what happened isn't know to me or the dealer who I purchased from (he bought it at dealer auction). Again, not sure of the exact cause of this, the car was thoroughly inspected by myself, my father, and a friend with old slk experience. Maybe a computer problem? (or even an incorrect/non oem pulley?)

Anyway, is there some way to adjust this without going to a dealer? I know everything is electronically controlled, so it seems unlikely, but worth a shot.

Edit: I should mention that there are no other issues with anything else on the car (excluding my lower seat heater). In other words no other engine/computer problems.

 

400rpm seems a tiny tad bit low. If you strictly had only cosmetic damage then the electronics shouldn't be changed. Did you try perhaps resetting your ECU by unplugging your battery then plugging it back in? Perhaps there is an issue on the TPS or MAF? Are you running any mods?

 

Unhooked/reconnected battery and nothing. Staring at the idle, it looks to be just a little under 400 (380>400). No mods on this car to my knowledge (let's say I'm 99% sure everything is stock).

One of the issues is that I don't know if it was cosmetic damage only. I was just going by my own inspection and the dealer/carfax report. Everything under the hood looked and still looks 100%. I am fairly certain no air bags ever blew, but that doesn't necessarily mean the damage was light. Both headlights are orig. (somehow...), but the passenger fender, grill, front bumper, and fog lights are brand new, the hood may have had repairs (under hood cover shows signs of having been removed/replaced). But in all honesty, it may have just been a good repair job masking damage that was more severe than I originally thought. Its hard to say for sure.

Like I said, everything on this car works great, no problems. Just a slightly low idle. I'm sort of afraid of the cost of going to the dealer right now. With the holidays so close I really don't have few hundred dollars to throw out the window. Are there any other potential fixes for the low idle. I would take it to the dealer if I knew they could just electronically adjust the idle, but somehow I doubt it would be that easy or cheap.

 

Maybe check the air filters to make sure they are not clogged and restricting air intake?

 

First place to start is the vacuum lines, air pump line (which is know to come loose), and the egr valve & lines.
Any of these will play hell with the idle.

Check the Emission label for locations.

 

And most assuredly will turn the check engine light on in short order. You need to find somebody that knows his way around a scanner and have him check the base idle settings and if the ECM has been chipped. What ever is going on, the "system" think everything is normal or the MIL light would be on.
Is this an automatic or manual trany?

 

Its a 6spd. No check engine lights are on, air filter and intake are clean. Right now, I'm looking at a pretty full week. I'll most likely have to wait until next friday to work on it again. If no luck by Saturday I may take it to the dealer the following week.