Mbenzer007

I have a 1986 300e (Manual) with 154,000+ miles on it. Now, I have done so many research on this topic and I cant seem to find the culprit. For hesitation, I would first start my car and when I would drive away it would feel as if there is full power,very fast. After 1 min, feels as though the power has been restircted aswell as the RPM. Ok powerloss hits, now when im driving if I hit the gas to speed away it would hesitate and "chuggle" a bit then take off. Now im chuggling- sometimes, this is frequent, if im at a stop light my RPM gauge would rev up and down around 500-1000 trying to stay alive. Then when I hit the gas to go it chuggles then dies. Along with all this there is a faint "Knocking sound" when im driving . Other than that the car is in awsome shape. People said its the Oxygen sensor to needs a tune up. If you think you might know the problem pleaseeee reply. I have taked it to some Mercedes shop and came back with no results. This Wed. a MB dealer will test drive it so hopefully he will figure it out. So, please help me if you know whats wrong!!!!!!

MB4JH

it could also be the coil.

Mbenzer007

Yea I will have the MB dealership take a look at that. Do you have the same problem?

pesuazo

Mbenzer007, I was having the exact same problem in my car.
1986 300E, but automatic.
I took the idle control valve out and cleaned it thoroughly with carburetor and brake cleaner. The problem persisted for another week, but less severe. I repeated the procedure the following weekend plus lubricated it with WD-40. I also cleaned the air intake, there was plenty of dirt attached to the walls just below the plate. The problem has not reocurred since (about a month).
Good luck.

jljimenez

Hi,

Did you fix that problem?, I think my car has something like that. Please, may you tell me anything?

Thanks in advance,

Best regards,

Woody

pesuazo

Unfortunately, many people only post "I have this problem" they get some suggestions but never come back to say "I did this, and it solved the problem".

Let's be a little helpful to other members, and post "HOW I SOLVED THE PROBLEM".

Mbenzer007

Hey guys sorry I was out a bit,

I took the benz to my dealer and he replaced my tensions and filters and such. From there the dealer said he could pin point where the problem is from. My car has improved a lot but still minor hestiation. He will do another round with the benz this week. I will tell ya how it goes.

-MBENZER007

soldsep

did you tell him about the things we said just to see if we might be right?

Cuz some of the time at the dealer they dont know anything unless you tell them about it and then they check it and then there like OH WELL... THAT WORKED!

Hendrich

Mbenzer007, I have been battling the same problem for over a year, though not as seveer as you described. With lots of frustration, lots of returns to the shop, thousands of dollars, and at the verge of selling my car just to rid myself of the problem, alas, I think it's finally solved. I had to drop my former mechanic of over ten years because he could solve or diagnoise the problem.

My new mechanic solved it in only two returns to the shop. Here's the history: 88 300CE with about 150k+ miles. First it was a tune up, then the O2 sensor, then engine mount (rough idle), then a valve job, then the fuel pumps (yes two), fuel relay, electronic this and that, then a used fuel distributor, etc. The fuel pump I went in twice because only one was changed initially. The tune up was done more than once, and the O2 sensor twice. Still the car would run o.k. for a while but would later stall, gargle and lots of hesitation. I also had the tach run like your. I may have missed a few things... That was with my first mechanic.

Then my second (and hero) mechanic. Frist he replaced the fuel relay switch something and the used fuel distributor that the first mechanic installed, who charged me lots of $$ for (he was trying to save $$ because I had already accumulated lost of deposits in my "new bank account" - his shop. That solved the gargling and hesitation - period. But he did warn me that idle would be rough for the next 1000 miles because it has to imbed. But car still stalled after a few days. The magic move was when he replaced the electronic overload module. So my car is back to normal aside for the occasional rough idle, which will be adjusted in a few hundred miles. I'd forgotten how much power the car had!

Hope that helps...

Mbenzer007

I recently switched mechanics two. Those where very hlpful tips thank you very much. My new mechanic found several issues with the car that was rather funny. Anywayz, he is right now replacing my engin mount. He alraeady put in a new tensioner, filters and such. That improved the car dramitcally. I still have low rpms of take off and hesitation. The hesitation though wnt to a minimum.

The dealer wants to fix the small things then truble shoot from that. After he replaces my mounts he can determine what the problem is. I will also suggest all of your ideas to him. Hopefully couple more trips and my 300e will be up to full power!!

jljimenez

Now I am investigating a possible problem about my car 260E year 1987, it´s about the potentiometer that reads the position of the air flow meter disk. I will keep you informed.

Woody

jljimenez

Hi,

I have got a clue from some people in Germany and Bamberger_1 translated it for me. Thanks Bamberger_1.

It was about the air-flow meter potentiometer, in fact this weekend I dismantled this piece –black plastic cover with four screws- that is attached at the Air-Flow Meter body and reads the position of the disk. The carbon lines of this potentiometers were worn in a zone –may be between the position where the disk is located when the engine is between idle and 3.000 RPM-. I cleaned this carbon lines, I gave more pressure to the brushes that run over this carbon lines and fit this element again. The engine now goes a little better but still hesitates –only when hot and between idle and 3.000 RPM, more or less-.
Now I think that the gasoline/air mixture is too poor because with the air filter removed, when I accelerate if I push with my finger the disk of the Air Flow Meter the engines goes up RPMs right, may be the reason that the engine runs better when cold is because the mixture is richer or may be that when I push, I put the disk at a location where the potentiometer reads right.

The reference that have printed the potentiometer is 3 437 224 015.

Please, if anybody knows how to get this piece, tell me.
Sorry about my English, I know it is not fluent.

Best regards,


__________________
Woody

1stmbenz

I have a 400E thats constantly stalling. I took it to the dealer. The dealer says its the air mass sensor. Hope this helps.

jljimenez

I had a similar problem and this problem is just solved, I got a complete set of an air flowmeter and fuel distributor from a sraped car -only 150,00€-, I changed this set and now I have a new car, I had forgotten the power of my motor. It seems the problem was the potentiometer that reads the position of the airflowmeter sensor.

If anybody needs more information, contact me

Woody


__________________

MBs Only Now

I know these posts are from years ago, but anyone having this issue might want to look to the ignition system rather than fuel system right off the bat (as is the case with many other MB issues). Although the fuel filter (and injectors) is exactly what my mechanic went to first, I insisted he look at the cap and rotor. This was after almost two years of headaches, with another owner and I on a forum putting our heads together to find the culprit. It turned out that once the car had been running long enough, the sparks and resulting heat from the worn parts couldn't maintain a connection. Symptoms include shorter and short periods after starting until the car begins to stutter, stalling, overall power loss, and the car often starting fine when it's cold. Cheap fix.