I have a 2003 S500 Sport. I have 2 questions:

1) Recently since the temperature in the SE has started to rise, my idle has gone from approx. 500 rpm to 900 rpm. When I turn off the AC it goes back to 500 rpm. Is this normal or is there a probelm? I have ran the AC before temps. increased and this did not happen.

2) My brake wear sensor just came on. I know I need to replace my pads and front rotors. Are there any specials tools, things to know, etc... when I do this? I like to perform this type of maintenance myself.

Chemist69

 

I would encourage you to get the "star service library dvd".MB dealers stock them and it is the same tech info that the dealer uses to troubleshoot/repair your vehicle.i use it and feel that for most routine maint you dont want to be without it.it is only about $100.as for doing the front brakes on the 03 S500 it is pretty simple,you will need a metric torx for the rotor hold down bolt,there are pins that retain the pads ,you will need to use a drift to tap them out,and just replace the wear sensors,they are only $7 each. beware of "BAS".alias brake assist system.if it malfunctioned during the pad replacement it will apply max brake assist to the calipers and you would not want your fingers to get smashed like a catsup packet on a concrete floor.please get the dvd.

 

Thanks for the advice. I will get the dvd.

 

I have looked into the DVD and I am gong to buy one. I not sure that will help my idle probelm. I am not getting an error message about this. It has just recently started running about 400 rpm higher with the A/C on. Anyone have any ideas what would be causing this or what I shoule check?

 

I've noticed my idle speed is up a couple hundred RPM lately in the heat of the day. It may be our heat lately kicks on the cooling fans quicker and the up-idle is somehow related to that. It's not troublesome and it doesn't show as a malfunction, so I'm going to let the dog lie unless somebody has an experience that argues it needs a look.

 

idle speed increasing is normal correct me if I'm wrong something to do with the AC Compressor engaging?

 

ill check how our car responds to ac compressor/cooling fan cycling on/off.i dont think that there is a noticeable effect on idle speed,but i will verify and post tomorrow.these cars occasionally "glitch" and you dont want to panick right away,your idle sems a little odd and i dont think you should see the rpm fluctuate from accessory loads being cycled on/off.the system in fact manages engine rpm,but only to maintain normal factory specs,not increase beyond them.