Engine stalls on deceleration

[flatif]

My 88 300e has just crossed 200,000 miles and is still going strong. It has developed a nasty problem of stalling on deceleration, such as when coming to a complete stop on a red light. The stalling occurs just before the car stops completely. On turning the key, the engine will start right back up and the car runs fine. The stalling is more noticeable on humid days and in the morning (it will stall once or twice in 8-10 stops run during morning commute).

I have taken the car to the dealer 3 times with this problem. This dealer has serviced the car since I bought it new and is familiar with its history. The dealer replaced a part (# 1 000-070-39-62, fuel regulator?) and adjusted idle speed etc. The problem is still there.

Has anyone else experienced such a problem? What was the remedy? It looks like my dealer has no clue on how to proceed on this one.

On a side note, the cruise control control-module is not functioning. This may or may not have any effect on the stalling. The dealer does not think so.

Any help on how to diagnose this problem will be appreciated.

Thanks

[DLGarza]

I had the exact same problem on my '88 300E. It seems to be a problem for just this year from what I've heard. I don't remember the exact part that needs to be replaced, but it was a problem with the cruise control. The cruise control didn't even need to be engaged for the stalling to occur. Have the dealer fix your cruise control and the problem should stop. My mechanic couldn't find the problem at first and since I didn't use the cruise control much, I never knew it didn't work. I ran into the fix on thebenzbin.com a few years ago and showed my mechanic. Once the cruise control was fixed, all was fine. If you need to know the exact part, let me know and I will look at my receipts when I get home.

Good luck,

Darrin L. Garza

[flatif]

Thank you Darrin.

If you do get a chance, I will appreciate the part number for the part that fixed your problem.

The dealer ran diagnostic on the cruise control when I told him that it works intermittently. Just like you, I use it rarely so I didn’t bother fixing it. He told me that the control-module needs to be replaced. It is located under the dash on the driver side.

F. Latif
-------------------------------------------------------
1988 300E
1996 C280
2000 E320 4-M SW

[DLGarza]

The problem is in the instrument cluster. The part that needs to be replaced is called a Hall-Effect Sensor or Speed Sensor. When mine had to be replaced, I only had 128,000 miles and that was back in May 2000. Yours lasted a long time. Anyway, at that time, the part was around $45 and my mechanic charged about $60 for the job.

Here's the information I got off thebenzbin.com website that helped me:

1987-1988 Mercedes 300E, 300D, 300TD, 190D, 190E

Cruise control will disengage intermittently. Engine cuts out when vehicle comes to a stop.

Beginning with the production date of May 1987, the Hall-effect sensor, which is mounted on the speedometer, may have a defective cold solder joint on the sensor output pin.

If your vehicle exhibits these symptoms;

1: Cruise control will not engage at all.
2: Engaged cruise control will disengage intermittently.
3: Your 1988 vehicle cuts out when you come to a stop but will restart immediately.

Gently wiggle the output pin. If any movement is detected, the sensor is defective and should be replaced. After June 1988 and improved part was made (stamped 6.88) even though the part number remains the same.

I hope this helps you. I'm sorry that I don't know the exact part number, but this should be enough information that the dealer, or any other MB mechanic should be able to fix this for you. Please let me know how this turns out for you.

Sincerely,

Darrin L. Garza

[Erich Borden]

flatif,

I have experienced this problem with my 1988 260E. The cruise control module was bad and the car would accelerate without warning. Talk about exciting! These units have "reference resistors" in them that go bad. The 1988 version is soldered into the module. In 1989 they can be removed and replaced. I was able to get a unit out of a 1989 300E and exchanged it. Works very well now. This is below the steering wheel under the dash.

I also had the stalling effect when I came to a slow stop. This was the overvoltage protection relay (OVP). These have failed on two of my Mercedes so far. I recommend you replace this first. Secondly I would take your car to have the alternator output checked. Sometime if you have a week alternator and you slow the engine speed when stopping this could be enough to kill the engine. The voltage regulators maybe bad preventing you from getting the proper charge. Autozone can check this for free in the car if you have one near you.

Hope this may help you

Erich

[SemperBenz]

I had the exact same problem on my '88 300E. It seems to be a problem for just this year from what I've heard. I don't remember the exact part that needs to be replaced, but it was a problem with the cruise control. The cruise control didn't even need to be engaged for the stalling to occur. Have the dealer fix your cruise control and the problem should stop. My mechanic couldn't find the problem at first and since I didn't use the cruise control much, I never knew it didn't work. I ran into the fix on thebenzbin.com a few years ago and showed my mechanic. Once the cruise control was fixed, all was fine. If you need to know the exact part, let me know and I will look at my receipts when I get home.

Good luck,

Darrin L. Garza

My 1989 300TE (with 193k miles and a production date of April 1989) has the same problem. If you go to various Benz sites you'll see that many of the late 1980 W124 had the same affliction.

Maybe it is time to try the old HES....

Thanks.