2003 S500 Rough Idle

Nov 22, 2006 | 08:35 PM

ChrisS500

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2003 S500 Rough Idle

Greetings,

I bought a used 2003 S500 a couple of months ago and the car was running smooth at that time. After I hit the 50K mile mark, I've notice the car would sometime idle rough when I'm waiting at a light and the car is in D. It's getting worse lately where it seems it wants to shut off during rough idle but then it's fine again. It wouldn't idle rough at first but if I'm waiting at the light for awhile, it would sometime happen, very rough idle, and then correct itself. When it's driving it's fine, the temp is in normal operating range and there is no codes thrown. Because it's out of warranty, is this a MAF going bad? If so, how hard is it to replace the MAF myself and whats the price tag?

Thanks in advance.
Chris

Nov 22, 2006 | 08:53 PM

newton22

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Joined: Aug 2005

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From: Sugar Land, TX

BMW E39

MAF is a possibility. MAFs are very easy to replace yourself. They usually cost about $250-350 and maybe over $400 if you want your dealer to replace it for you.

Nov 22, 2006 | 09:24 PM

esprit

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Lucky you, rough idle in Drive. My '03 idles *kind of* rough in park only and the shops, including the dealership don't have much to work with. They assure me it's normal, the last mechanic said: "The dealership told you they can fix this? They can't fix this. The only way to get a smoother idle in Park is to buy a Japanese car." I think I have narrowed it down to the transmission mounts, since I hear a knocking sound when pressing the gas abruptly at around 10mph and feel the knock on the stick.

Anyway, replacing the MAF yourself is VERY easy, take it from someone who has done practically no work on cars. Just follow these instructions, that's what I did last weekend:

https://mbworld.org/forums/showthrea...&highlight=maf

Get your MAF on eBay, most posts on the forums indicate that you should buy the OEM BOSCH MAF as opposed to the aftermarket ones. You can also get the insert only to save money. Taking the insert out of the case is easy -- you can do it with a torx security bit (recommended) or use thin pliers to gently unscrew the screws, while holding them on the side.

Regards,
esprit

Quote:

Originally Posted by ChrisS500

Nov 22, 2006 | 09:26 PM

ChrisS500

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Thanks guys.

If I have the dealer diagnose the problem with it out of warranty, is there a charge that the dealer will charge just to diagnose?

Nov 22, 2006 | 10:15 PM

esprit

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At my dealership, it depends on the complexity of the issue. For example, they would not charge anything to inspect the brakes, but would charge to try to determine the cause for my rough idle. I would't expect them to charge in your case, but can't be sure. Best thing to do is give them a call and ask. You may have to make an appointment and speak with the service advisor (when you go in) and ask them. It is sometimes hard to get answers over the phone, but you will have to see a service advisor when dropping the car off and can ask at that time.

Congrats on your new vehicle, it is state of the art. I purchased my '03 s500 in September. I sometimes concentrate too much on a small issue and forget to enjoy the car -- big mistake!

Keep us posted.

Regards,
esprit

Quote:

Originally Posted by ChrisS500

Thanks guys.

If I have the dealer diagnose the problem with it out of warranty, is there a charge that the dealer will charge just to diagnose?

Nov 23, 2006 | 03:42 PM

ChrisS500

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Thanks. I love the car. I've notice the rough idle problem happens only when the car is warmed up around 100C. Anyone else experience this?

I wanted to see the MAF so I took the airbox off today and found this. I'm not mechanically incline so should I be concern about the below? Could this also contribute to the rough idle? Thanks in advance.