1995 E320 Sedan 104 hesitation - PeachParts Mercedes-Benz Forum

83scrambler · #1 02-26-2007, 09:33 PM

Alright guys.... I know I am getting closer...

I have found another one of us that has had a problem much like mine. We have both described the hesitation as the following: Light acceleration is fine (if you are really light on the gas and crawl through the intersection, the problem is almost un-noticeable). The harder you push on the gas (or if you floor it), you get major hesitation. Then all of a sudden, you would get a huge rush of power as the hesitation ended. It was quite unsafe to drive!

He posed this question to me:

"Have you looked to see if you have a MAF potentiometer on your car?"

I looked and he told me where to look. I found that our cars are very different in that he was talking about a 1990 SL. I am wondering if I have the same MAF potentiometer somewhere hidden in the airflow system.

Here is how he defined the part (MAF Potentiometer) to me:

"I replaced mine and the problem went away completely. The copper
track that the wiper slides on wears out, and you get a "dead" spot just
above idle. When you're in this spot, the car adds the appropriate
amount of air but NO fuel because the fuel pump doesn't think you
need any. The result is stalling/hesitation, then you get a burst of power
once you pass that "worn out" area.
I found that you can only buy the entire air flow meter ($950) from
Mercedes, but the potentiometer on the side is replaceable very
easily.
Remove 4 screws and a connector, then replace. Takes 5 minutes. The
Mercedes tech I go to (independant) can get the potentiometer and I
think I paid about US$90 for mine."

Please tell me that this is something that my year and make has!!!!

I have just replaced the Bio-degradable wiring harness, and new plugs too, I have spark plug to coil connectors on their way right now...

Thanks for all your guys help!!

Justin

Ali Al-Chalabi · #2 02-27-2007, 12:47 AM

Your car has a hot film MAF snesor that is known to cause running problems and require replacement on a lot of M104 engines. It's hard to say for sure over the internet that it needs replacement without seeing any data or possible stored codes. However, it is a possible culprit, it does take 5 minutes to replace, and the part costs more than $90.

JMaxwell · #3 02-27-2007, 01:58 AM

83:

Based on a very similar past experience, i would guess your problems involves the spark plug boots (and not the coils themselves). I hope you ordered them too, because as a lot of members here will tell you, these are a major source for the type of problem you are describing, and are really cheap to replace. Good luck.

83scrambler · #4 02-27-2007, 07:45 PM

I just got the coil to spark plug connectors replaced and it seemed much better on a short spin, although there is a slight hesitation when putting the pedal down at times. I'm going to take the car to work tomorrow and will get a chance to get it out on the interstate. I'll have to report back then.

I have yet to replace the coils, but have replaced the plugs.

The afore part mentioned... the MAF Potentiometer... So I do indeed have something like that. Can you tell me what its called? You mentioned that its more than $90.00... so if not 90 then what do they want for it and is there a source?

This car is going to become my primary transportation and I can't compromise the operation of the car when I depend on it to get to work.

Thanks for the help, the problem seems to be better but as I said I will have to look into it a little more as I am sure that I felt a shutter when giving it 3/4 throttle.

Justin

dtf · #5 02-27-2007, 07:48 PM

How many miles on the spark plugs?

softconsult · #6 02-27-2007, 08:16 PM

Had the same thing on a '93 M104. The MAF (Just behind the air cleaner in the air stream) was the culprit. You could not smoothly accelerate from stop. As you describe, all of a sudden it takes off.

On-line look up for my '97 S320 a shade over $200. called Air Mass Meter on one site. Luckily mine was replaced about 40,000 miles ago.

Common failure item.

Steve

Arthur Dalton · #7 02-27-2007, 08:46 PM

< >>

With what ??

Also, check codes.

david s poole · #8 02-28-2007, 12:25 PM

you need bosch f8dc4 plugs[yes they are still available--worldpac] and you need a mass airflow meter[approx---$300] if the wiring is done this will fix it.make sure after you replace the maf that you leave battery disconnected for about ten mins to zero out the adaptions[changes the computer makes to try and compensate for the bad maf].

83scrambler · #9 02-28-2007, 03:18 PM

Thanks guys!! I will have to check into the plugs that I put in as far as the number that I got. I got Bosch platinums from Autozone that were listed for the car. By the looks of it you all mention the same plugs so I need to take them out and check to see what I got.

Why do they have to be so specific as there are others that are listed at parts stores?

suginami · #10 02-28-2007, 04:29 PM

Quote:

Originally Posted by 83scrambler

Thanks guys!! I will have to check into the plugs that I put in as far as the number that I got. I got Bosch platinums from Autozone that were listed for the car. By the looks of it you all mention the same plugs so I need to take them out and check to see what I got.

Why do they have to be so specific as there are others that are listed at parts stores?

You need to take out the platinum plugs because they are resistor plugs and your engine demands non-resistor plugs.

Only use the plugs referenced above.

83scrambler · #11 02-28-2007, 08:12 PM

I just found some (bosch f8dc4)for $2.00 a plug, that a decent price?

I just read that it is possible to improve the performance of the MAF sensor by cleaning it with Isopropyl Alcohol. Anyone heard of anythign like this?

I just don't want to kill anything in the process.

Thanks,

Justin

Arthur Dalton · #12 02-28-2007, 10:08 PM

Get rid of the Plats and put in the correct F8DC4 before doing anything to the MAF.

83scrambler · #13 03-01-2007, 08:14 PM

Just got them ordered... Hope this makes some inkling of a difference!!!

Arthur... You know anything about Headrest motors? I need one for my drivers side.

And.... anyone hear about cleaning a MAF with Alcohol ?

Thanks!!

Justin

genesiscg · #14 03-03-2007, 12:47 PM

My 93 300E is having this exact problem. I replaced the Mass Air Sensor 10k ago to fix a rough idle problem (it didn't) The question is does the MAS #0000940548 include the potentiometer that is being discussed? Can I test the pot with an ohm meter to see if the dead spot exists and can I use contact cleaner to if that helps the problem?

83scrambler · #15 03-03-2007, 05:42 PM

I would like to know more about cleaning the MAF sensor. I never got much response to that... anyone, anyone??