tmwsccsh

All,

UK Based owner here asking for some help as getting no joy over this side.

First posting too!

I have a strange problem - when she gets up to temperature, after about 4 or 5 miles, the idle becomes rough, revs start going all over the place at lights and things and it's almost as if she is going to cut out. If you do turn her off, you can't start her again for 4 or 5 hours, then all is fine until she gets up to temperature again and it all starts again.

So far, crank position sensor has been changed, HT Leads, Disty caps (these have also been dried off behind just in case) but my mechanic chap is now at a loss.

Where else can we look to get this resolved? I have been without the car now for 2 months - fortunately I have another - but I want her back!

Thanks in advance for any help.

Regards

Tim Watts

scottejupiter

I had some cold starting and idle issues that were resolved with a new OVP relay -- a $50 part. Not sure if a 1995 is the relay or the base control module. But something to look at.

morganb

Tim, I am interested in this as well, I had the same issue, changed the Crank angle sensor and all was good for about 2000 KMs. Same issues have surfaced again, I am wondering if the Crank angle sensor is dirty and therefore cant read properly, you could ask your mechanic to check and clean it and see if the issue goes away for a while. Do let us know the result.

tmwsccsh

All,

A potential encouraging update.

She has finally been put onto a computer and a problem with the Mass Airflow Sensor / Meter has been identified - this is interesting as, to digress slightly, I purchased a hard-top a couple of weeks ago and the place I got it from is a Mercedes Restoration place - whilst there I mentioned the problems with her and they said either Crank Position Sensor or Mass Airlow Sensor / Meter.

Anyhoos, it would appear that this part on the SL500 is not a cheapy - £600 or so from Merc direct or £450 for a non-Merc one, but sourced one off eBay for £100 used with a warranty. So hopefully that will arrive on Tuesday and can be fitted and all will then be fine. Frustratingly, I am away for work on Wednesday and Thursday so, if it does solve the problem, won't be able to collect her until Friday morning, but at least there is now a positive step and there could finally be some light at the end of the tunnel.

But, this does lead to an interesting question. As advised previously, various parts have been changed already with no success and, so far as I am aware, these are still on the car. This means that I am potentially looking at a bill for some parts (and probably associated labour) that I actually did not need in the end. So should I state my case on this and hope that a reduction is forthcoming or just be grateful that there's some other bits on there that have been renewed - what's everyone's thoughts on this?

Regards

tmwsccsh

Chetter

Would someone share with me as to where the crank pos sensor and /or mass air flow meter are located. A parts breakdown pic would be great. I have a similar problem.

tmwsccsh

Alas I can't help you - mechanic has done everything for me and don't know myself...

TMW

scottejupiter

I"ve had some things done on my car that I probably didn't need. Car repair seems to be an art form as opposed to a true science. Try different things until something works. But if you are going to keep your car for a long time, you would probably need some of those parts replaced anyway.

morganb

On my RHD car it is at the back of the engine, on the Left side when looking towards the front.

tmwsccsh

Good news, everyone!

Got her back today - all sorted and all working really well - and another years MOT on her as well as that runs out on the 18th.

So it was indeed the Air Flow Sensor in the end.

Here's to a few more miles of enjoyable motoring - can go and collect the new hard top next weekend now too!

TMW

scottejupiter

Glad you got it handled!

morganb

Well Done, I have an update as well after reading your idea. Put on my new Crank Angle Sensor and got the same failure as before. Sprayed some cleaner on the Air Flow Sensor and cleaned a sensor at the front and now all seems good. Only drove about 8 KM so I need a good run to prove it is fixed.

scottejupiter

Morgan, can you post a pic of what you cleaned? Not sure what the airflow sensor looks like. Is it under the black plastic housing?

Did you use break cleaner?

morganb

Its in the intake, take off the air-cleaner cover and you see it down through a mesh. My mechanic used a sensor cleaner, not sure of brand or anything. You spray it with the engine stopped. He sprayed a fair bit. Took about 20 seconds for the car to start afterwards as well, it normally starts straight away.
Check out That is what we did but left it in place on the car.

morganb

An Update. My car is not fixed. Can run OK from Cold for a few minutes and if at higher revs once warm. If warmed up at low revs then it runs rough and can stall. Once stopped it will not start so it sounds the same a TMW's problem.

scottejupiter

Try doing a search on this other site.
http://www.benzworld.org/forums/r129-sl-class/