stumbling ML320 with agressive pedal - PeachParts Mercedes-Benz Forum

sdanville · #1 11-19-2006, 10:43 AM

Agressive pedal is not anymore accurate.
Now anything more than a feathered pedal causes misfire.

1999 ML320, 120,000 miles. replaced plugs, fuel filter and pump at 100,000 miles..and cleaned erg tube. CPS replaced at 90,000.
cleaned air filter last night. mass air flow replaced this week.

I drive like a grandpa. last week i thought i should open her up a little...nothing happened when i pushed the pedal half way down...no rpm increase no acceleration. ..then it felt like it was hitting on about 3 cyl and the check engine light came on. I tried it 3 times, 3 times this happened. I turn the key off and it will start back up running on all 6...If I take it easy I am ok. My buddy says replace the gas filter again. I thought I would post here first. I have more updated posted down this Thread.

dkveuro · #2 11-19-2006, 09:57 PM

First, you need to get the codes ...then fix each one.
It's possible you have coil/s problems.
Getting on it hard and then missfire, this seems likely.

You'll likely to find random Missfire codes...P0300 and up.

.

MB208 · #3 11-19-2006, 10:24 PM

I would get the codes first but it sounds like an air mass meter issue, that will kill power on the car if its bad.

sdanville · #4 11-19-2006, 10:35 PM

Thanks.
I almost bought one on Ebay a few weeks ago as a back up. From what I read on this forum, its just a matter of time when you buy one.

There is a EBAY seller -- selling information how to fix the MAS Cheap.
I ran a search here and found nothing. Go figure.

Ive been looking for directions on mass air flow sensor cleaning. havent found much. Read what is on the can. Vague for the bosch in a ML320.
i pulled mine out and sprayed this thin wire a dozen squirts.
it looked clean before i started.
there is a little cover, looks like it is glued on. Anyone know if I am supose to take that off to fine the dirt ?
It ran better post cleaning...I didnt puch the gas down too far..yet.

Johnhef · #5 11-21-2006, 09:22 PM

With out seeing codes, I'll second the air mass sensor diagnosis. they are known to cause exactly what you describe.

Sam1951 · #6 11-22-2006, 08:34 AM

I just bought a 98 ML320. The codes is easy to get. Go to your local auto parts store, and the'll be glad to run a code scan. The hook up is under the drivers dash with a little snap cover, its a usb or a common plug. Also I received a recall for the coils. There are one coil per cylinder. My coils weren't changed because they said mine were after the recall serial numbers. I would never trust what any MB dealership tells me. Hope I helped,
Sam

sdanville · #7 11-22-2006, 08:44 AM

UPDATE 11-27-6 The new Air Mass sensor arrived. I installed it in 120 seconds. Drove 7 miles. Still have problem. I am hoping the computer has to take time to adjust. I will get the codes checked as advised today.

UPDATE : Codes read. PO300. multi cyl mis fire. PO301 to PO305. mostly cyle #2. autozone guy said plugs or wires. I only have 20,000 miles on these plugs. all of a sudden they go ? Bosch platinum 2. he wondered if i put them in tight - gapped them and put the caps on tight. yes yes yes.

DEC 1st 2006 UPDATE: One thread I read the owner said the MAS installation didnt help until he had his codes reset. I have not done that. Another said the dealer should update the computer codes. That sounds like it should be free like windows update. Can anyone verify?

12/8/2006 Today my Mercedes Is running great. I believe CURED.
the dealer installed 2 cats, reset the codes, and fixed a vacuum hose problem. The service mgr said he wanst sure what was done on the vacuum hose. I wish I had exact details to post. $80 was their labor charge. Cats would have been $3,000 but fixed under warrenty.
12/11/2006. Not Cured totally. Rough Idle, check engine light back on. I bought a code reader today. PO170 PO173. Ive changed the leading causes of these codes. (MAS)
jan 2007 - Ordered my 2nd New Mass Air Flow Sensor. Waiting for arrival. I suspect and almost hope my 1st one was defective.
JAN 13 UPDATE 2007 2nd new Bosch Mass flow air Sensor made no improvement. I sprayed starter fluid around the engine at idle and the rpm's picked up. I then found a vacuum gizmo had come off. My only problem now is a not so perfect idle. slight mis. not enough to give off a code.