Engine stalled at traffic lights and stop signs

[ps2cho]

Get it from autohausarizona.com For my 260E it shows $54.

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[xsun]

seems like i figured out the problem without spend a buck! After i removed poorly wired CD changer, everything go back to normal, no more stalls and rough idel. I guess they wired CD chager into Engine control system.

[Brian_I.]

Hey Xsun, just curious, how do you adjust the engine idle speed?

[appatula]

Originally Posted by Brian_I.

Hey Xsun, just curious, how do you adjust the engine idle speed?

I think he adjusted it via the throttle cable adjustments. I don't think this is a good band-aid for a low idle, as (PLEASE CORRECT ME IF I"M WRONG GUYS) purposely adjusting the cable to attain a higher idle RPM can cause the torque converter to heat up when your sitting at a stoplight in (D) drive.

[rayhennig]

Wrong, wrong, wrong.

Idle is controlled by whatever fuel injection/management system you have. Mine's KE-Jetronic with a 'mechanical' MAF, yours may be later with the HFM management and a 'hot wire' MAF.

Either way, tweaking idle speed with the throttle cable confuses everything as it opens the butterfly valve and allows air through. There are idle control valves to do that. The management electronics will be utterly baffled by these tactics. I know this because a young MB specialist tried the same thing on mine when I complained of stalling.

The ONLY answer is to find the root cause of the stalling problem. With mine, it was a cheap rotor arm but I suspect yours doesn't have one. Assuming you'r is the later HFM system, I cannot say more but there are loads of posts here and elsewhere that address this.

All the best.

RayH

[appatula]

Originally Posted by rayhennig

Wrong, wrong, wrong.

Idle is controlled by whatever fuel injection/management system you have. Mine's KE-Jetronic with a 'mechanical' MAF, yours may be later with the HFM management and a 'hot wire' MAF.

Either way, tweaking idle speed with the throttle cable confuses everything as it opens the butterfly valve and allows air through. There are idle control valves to do that. The management electronics will be utterly baffled by these tactics. I know this because a young MB specialist tried the same thing on mine when I complained of stalling.

The ONLY answer is to find the root cause of the stalling problem. With mine, it was a cheap rotor arm but I suspect yours doesn't have one. Assuming you'r is the later HFM system, I cannot say more but there are loads of posts here and elsewhere that address this.

All the best.

RayH

That's exactly along the lines of what I was thinking. Best to adjust your idle mixture with a DMM capable of measuring duty cycle, this will fix most idle issues.

[Andrew_Culture]

I'm also having the stalling problem, it's fairly intermittent though. I only picked the car up a few days ago and it’s a damned shame that after spending weeks convincing my wife a W124 was the right car to get that it stalled every time we slowed down or stopped, she made me go home and take a different vehicle instead!

I bought this car off an enthusiast and Merc parts dealer who had replaced all the HT leads, alternator etc very recently and he reckons the stall is happening because of a vacuum leak so I’ve got our super hero mobile mechanic coming to check that out in a few days time.

In the mean time I’m going to have a look for that fuse, if that’s all the problem is I’ll be a happy chap indeed!

[ps2cho]

I doubt its a vacuum leak as it would have to be a massive leak which would show a lot of other driving poiwer + fuel economy problems.

I'm sure its just the OVP. Get that changed first before paying him any money.

[Andrew_Culture]

Thanks for your help, it's really appreciated.

I'll take the battery out and check the fuse tomorrow, and of course I'll report back!

[Andrew_Culture]

The fuse was fine, albeit jammed in there like a right sod!

I took the car out for a spin after putting the battery back in and it didn't stall once, as is the nature of an intermittent fault!

[73Elsinore]

Originally Posted by appatula

This sounds like either, MAF, OVP, or ICV failure

As far as I know, the HFM-SFI M104 does not have an idle control valve or an idle air bypass valve. I had my engine top end all apart during the head gasket job and I never found any devices in the intake or on the manifold except the throttle body itself.

Someone please correct me if this is wrong...

[Andrew_Culture]

Our friendly local mobile mechanic just popped over to take a look and found a loose tube under the air filter which he has fixed.

He says I need to get a hole in the exhaust fixed before any CO2 problems can be diagnosed, so it's going to an independent Merc specialist tomorrow.

[loclark757]

I have a 1988 300 E. Fuel economy has become terrible. Ive put a lot of money into the car. It stalls out when coming to a stop. If I go into the grocery store and get back to the car to leave it sometimes takes 10 key cranks to start the car. Then just keeps stalling out. Its gotten worse over the past couple years. Air and fuel seem to not be getting along...

Im thinking its either OVP or Idle Control Valve...About to take a look when the weather clears

[Andrew_Culture]

A quick chat with the parts people at my local Mercedes dealership (preceded by lots of long confused phone calls with local scrap merchants/ breakers yards) revealed that a brand new OVP unit could be mine for just £70. At this price I decided to take the risk of replacing what might be an already working part and jumped in my car and headed across town to hand over some cash to said franchise holder. Pausing only to stall ten or eleven times of course. So now I’m the (proud?) owner of a brand new Mercedes OVP unit, and tomorrow morning I’m going to fit it and see what happens, I’ll report back here of course.

Oh, I'm writing this up on my blog now! -
http://lawsie.blogspot.com/2009/11/m...n-slowing.html

[Andrew_Culture]

The new OVP relay was very easy to fit, in fact I don’t think I’ve ever done any work on a car that was so brief and easy.



I took the car for a spin to see if it would still stall. I held the brakes on corners, held the brakes at traffic lights and generally did everything I could to make it stall and it didn’t. I was feeling cautiously optimistic, and decided to go to our local farm shop to buy some gourmet mayonnaise (I tell you this, because sometimes details are important) and had to hold the brakes for an age waiting to turn into the entrance. Shudder, poot, the engine stalled.

I gave up on buying Mayo and headed home. My optimistic side is trying to tell me that the stalling problem wasn’t as bad, but my pessimistic side is telling me that if the Mercedes specialists can’t fix this problem on Monday then I may have to sell the car. I’ve only had it two weeks and have only done 115 miles, and 100 of those were the drive from where I bought it to my home!

[Andrew_Culture]

I’m just back from the independent Mercedes specialist ‘Prestige’ in Ipswich with some good news, some bad news and some weird news.

The good news.
The idle circuit air hose was badly split so they taped it up and ordered me a new one, cost is just £12! This will probably almost entirely eradicate the stalling problem. They noted on the diagnosis report that the OVP unit had been replaced, so I feel kinda like I did the right thing in replacing it.

The bad news.
The exhaust manifold is cracked and the oxygen sensor has become one with the rust therein. The catalytic converter is also shagged (my word, not theirs). So there’s air rushing in where air ought not to be rushing in, and the engine is getting all confused and running far too rich (hence the petrol smell I described earlier). The catalytic converter is contributing to the problem by kinda suffocating the engine, thereby twisting the knife that cases the stall. A replacement oxygen sensor will cost about £136.00 (not too bad), a new catalytic converter will cost £1162.00 (oh mercy).

The weird news.
The idle circuit air hose will be fixed within the week, and should almost entirely eradicate the stalling problem, in fact it’s already FAR improved with the Heath Robinson repair they put in place today.
If I’m happy with the performance of the car after the hose has been replaced then fine. If it’s still an issue then they’ll replace the oxygen sensor, mig weld up the holes in the manifold and remove the catalytic converter entirely – it turns out cars as old as mine don’t legally need one! So I’ll feel a little bad that my car is chucking out some nasties into the atmosphere, but that will be nicely balanced by the fact that I’m keeping an old car on the road! Keeping an old car going (to a certain extent) is surely better than buying a brand new car? Replacing the catalytic convertor is quite simply never going to happen, in fact if I was forced by law to replace it I would have to scrap the car as I can’t afford it!

[73Elsinore]

Originally Posted by Andrew_Culture

Replacing the catalytic convertor is quite simply never going to happen, in fact if I was forced by law to replace it I would have to scrap the car as I can’t afford it!

Well done Andrew. In regard to the knackered cat converter, what about an aftermarket cat, i.e. a non-factory part? Are those available to you in the UK? On this side of the pond, that is an option in locales that allow it by law. Just an idea. Please keep us apprised of your progress in solving this stalling problem. Pete

[rayhennig]

Originally Posted by Andrew_Culture

A replacement oxygen sensor will cost about £136.00 (not too bad), a new catalytic converter will cost £1162.00 (oh mercy)!

There are places that have genuine MB cats for far less than that. In your shoes I would probably junk the cat but if you come over all green, you might find one around 500 Euro. Then there's shipping and installation costs but you should be well short of £1100.

RayH

Try:

www.mb-parts-teile.com
www.speed-autoteile.com
euromercmercedesparts.co.uk

[Andrew_Culture]

Yeah, that was basically the price from Merc in Germany. We can get non-factory parts (we call them Pattern parts) but the older the vehicle then the less there are on the road, then the less chance there is that anyone will make pattern parts.

Thanks as always you lot!