I have a 2000 ML320, Bought the OBD2 reader, When the engine is cold, it dosent want to start on the 1st try, it will on a 2nd try, it runs rough until it fully warmed up. I do keep =getting a code P0100, I have replaced the Mas Air Sensor with a rebuilt, was still getting the same code, Replaced it with a new one, Took it to the dealer where they put it on there computer, renormalized the setting, Still having the same code & issue.
Any Ideas??

 

Don't bother with rebuilt MAF period! Don't bother cleaning it either. Purchase brand new from dealer, check with them if you can just buy the insert. once you put new sensor in clear the code and let it idle for like 5-10 min. so it can adapt. check or replace engine air filter often. Vacuum out the air box. Dirt kills these sensors pretty quickly. Regarding po100 code don't know right off my head what that means. Oh yeah you can test if the MAF is bad heres how, start the car, drive it around a block warm it up, once its warm, give it some gas or floor it and if it feel like its not a smooth acceleration feels more like some shuddering or weak in power most likely the MAF sensor.

 

Yea, that was my last purchase, Brand New. Still didn't work. Thinking it my be the fuel pump or at the least a fuel filter...going to do a pressure & bleed down test this weekend.

 

I changed the air filter as it was not changed for 20000 miles approx, and it took care of MAF code. Sop try to do the same.

 

Found out it was my Oil sensor, it had gone bad, Unplugged it & the car runs fine now....Change my filter regulatory
Thanks for the reply

 

My problem turned out to be the EGR valve not closing completely. For my post on diagnosis and repair, see this.

 

 

 

I'm only a newbie .. sorry Is that the correct link for C-Class Coupe (CL203) C220 CDi (the engines are similar as in W203)? .. I put the new post here .. please move it if you feel it should be in better location.
https://mbworld.org/forums/c-class-w...ml#post7471078
BTW: I bet similar issues are happening in bigger Merc motors too. Similar engine components brands and sensors are used there.

 

Hi everyone, I'm lapsed member so think of me as a 'new' newbie!

Hello to all the present and past members, it's good to be back.

I'm not sure how this works but i think this is the thread I need to be on. Not sure of the protocol, but I/m sure you'll all let me know!

Anyway, I have a 2002 W163 ML500...and I love it! I've had it for 8 years and been fastidious with its maintenance. Whenever it gets any sort of problem I get it fixed straight away. I only run 98 Ron premium fuel and get all the oils changed every 5000 k's. The car has always purred like a kitten...just magnificent on long cruises to see friends in the bush.

But now I have a problem and its intermittent. When I'm in stop start city traffic the car will sometimes fail to accelerate...it feels like a massive loss of power/fuel. It's always at low revs, once I'm up and running the fault disappears. Some days when driving to work it doesn't happen, so its very hard to get the mechanic to diagnose the issue.

The first thing he tried was to change the air intake feed. (It connects to the ECU and through this the fuel flow is regulated is what the mechanic told me) It was fine for two days then it started to happen again. Next he replaced the entire fuse box. Not only did this fix the problem but a dash cluster light that was out came on again! But alas after a weekend road trip of over 600 Kilometres - without a problem and purring like a kitten - once back to work on Monday the fault started again!

The check engine light has come on, but then the next day its out. he did a diagnostic and found the check engine data that said it was a 'power to the sensor' problem. When it happens I will clear the 'flat spot' if I put the accelerator to the floor...but in city stop start driving...not very safe.

Anyway I'm now getting very frustrated. Has anyone had a similar problem and if so know how to fix it?

Thanks for reading, all the best.

Stu.

 

Stueclark, Have you got any OBD Error codes to share? I'm sure you will get a long list of codes if you have Check engine light on the dashboard. STAR diagnostic would be best, Bosch one is also quite good, but even I don't have an easy access to it ;(

 

What does clear the flat spot mean? People have had issues resembling yours that ended up being a coil and/or wires. No one will help you here unless you have codes from a quality reader.

 

I was planning on cleaning the MAF sensor on 1999 ML320. It's on the third sensor in 5 years. The sensor in there now is marked PBT-GF-30 and the box I think it came in is marked 1120940048. I'm a bit hazy but am pretty sure I finally went for a Bosch part after two short duration failures. Both of the numbers above seem to come back to Bosch.

That sensor has been in for 2-3 years.

This car carries permanent codes of P0720 which I ignore because it has had the transmission connector replaced long ago and it runs just fine as far as transmission is concerned. (Consider it a non-issue for now)

NOW - Wife came home yesterday with rough running, bad idle, poor/negative accelerator response, the whole deal. Scan reported multiple mis-fires and fuel trim unbalance. I cleared those codes and they don't come back while running in the garage. Idle had been "jerky" for several months and I had planned to take it to the dealer, who has now moved 20 miles away.

TOMORROW- Replace air filter and check ducting. Look for leaks and blockage.

QUESTION- Clean MAF or not? If clean, remove insert to clean it?

 

Hi OU1954,

I had similar issues, (2002 ML500) intermittent, acceleration, rough running, and a diagnostic test said I had a MAS and power problem. I replaced the MAS, no difference, I replaced the fuse box, this fixed a 'cluster globe out' issue but not the intermittent rough running. Finally we serviced the throttle body and as it turned out it was intermittently stick. Problem solved and the car is purring like a kitten once again.

I hope this helps, good luck!

Stu.

 

I'll have a look. You didn't say which way the throttle was sticking but I assume it was sticking in both directions. Even so, the system should have been adjusting to whatever position it was at the time. If you have a chance to expand, please do.

The days are gone when you could look at the throttle and even see if the accelerator pump was working.

I spent my entire career as an engineer in high technology business but really don't think we need all these hidden features in our cars today, or else, make the design information available. Actually for several years I made assembly equipment for car manufacturers, including Mercedes Benz. I even went to one of their factories in Germany, but that doesn't help me now.

 

Hi All, I am hoping for some help please?
Get right to it! Car runs perfect in park and neutral but put it into drive and it is very rough. I have replace the MAF with a new Bosch. Car recently full service. No codes showing. I did disconnect the battery in hope to reset. Ran car in park for 30 minutes. Since the ML is currently unregistered and in still position I am thinking a good drive may fix this problem ( once registered ). Any thoughts please? Rob in Australia....