I just replaced my air filters with a set from Pep Boys and they said they could install them for free, so I said sure thing. I'm now getting an occasional rough idle, so I took apart the air filter and found that they forgot to tighten down one of the screws and aparently some dirt got in. I cleaned it up and reinstalled everything but I'm still having the problem. No check engine lights yet.

UnfortunattelyPep Boysthrew away my stock filters so I can't go back, but before I run off and buy some expensive OEM ones to trouble shoot I'd really appreciate any help. Thanks!

Forgot to add car details: 2002 S430 with 65k miles, no prior check engine lights, oil changed regularly.

 

maybe the air filter housing/cover was not installed correctly. or maybe not
sealing well around the maf sensor. the type of filter should not effect idle.

 

Yes the air filters do not have any influence on the idle. I have a rough idle as well in my S430, last Saturday I replaced all the spark plugs which took me about 2 hours to do? I changed the air filters, and the car was running smooth, took it out for the weekend, and comes Monday morning, the rough idle is back. ticks me off. So, obviously there is something else going on. Next step would be to put a injector cleaner in my tank see if that makes any changes, if not, I will have to get it on the scanner and see where it's coming from, and I mean a scanner, not a code reader because I do not have a check engine light coming on, so it probable is not something serious, but it's annoying as hell. Somebody suggested to check the motor mounts, but the car has only 98000 miles on it, if the motor mounts where the problem, then Mercedes put in some serious crappy motor mounts if they deteriorate after 98000 miles, mine where fine. In my opinion, it has to be some sensor, it could be the idle control sensor. In the mean time, the tune up gave me a considerable better gas mileage, that was a winner. Lucky for me, nothing was seized up, and the plugs came out reasonable easy, providing you take your coil packs of. I post my next experience after I'm done with the test, and when the rough idle is history.

 

What was the outcome???

 

Cleaning the throttle body helped a lot, let the engine run and spray little spurts of throttle body cleaner, make sure you use throttle body cleaner and not carb cleaner, that is too aggressive. Next, I replaced the TPS, and the MAF sensor, and the rough idle is now history, car runs as smooth as a baby skin.