Bighouse

I have a 99 ML320. It has started running a bit rough, spluttering when accelerating hard and does not seem to rev much over 3500 rpm particularly when going uphill.

I have read some of the posts on here and purchased some new plugs, leads and a new airflow sensor. I am going to try and replace these items myself.

If I replace the airflow sensor does something have to be re-programmed for the new sensor? Also, could changing the above sort out my problems. I am on a bit of a tight budget at the moment and did not want to go to a main dealer!

Thanks.

Pottie

You could try to clean up first like I did...
First clean up the Air Filter if u re using K & N or replace one if you dont use K & N then you could clean the MAF by dip them to 70% alcohol..u gotta find the DIY for MAF and all materials you need is very affortable...
If those arent working then you may need to change MAF which is running close $200...dont change the spark plug yet if you re is not due...
Good Luck....

Bighouse

Thanks - I think the plugs need changing anyway as I did not do them when it was last serviced. I will try the things you advised. Cheers

GDawgC220

Its also been suggested to try brake cleaner. Take the MAF, put it in a ziplock bag and spray some brake cleaner in there and let it sit overnight. Take it out and let dry.

MJ50

or u can buy a can of maf sensor cleaner...

Bighouse

If I fit a new MAF sensor rather than cleaning my existing one will I need to get anything re-programmed or will it work okay?

GDawgC220

Just plug and go. It'll re-adapt itself after driving for a little bit.

Darkmann

You're an interesting fellow. You spent all that cash buying all that stuff based on what you get from the forum???? C'mon, it probably would've cost less to have the truck diagnosed properly at a dealer or indie, and then get the right stuff to fix the problem. You already know we can't tell you for certain if replacing these pieces will resolve your problems, so why even bother to ask. I'd say start with the MAF (BTW, did you spend $400 for the MAF or did you just get the sensor which costs about $100?). If the plugs haven't been changed and you're near 100K, replace them. If that doesn't do it, take the truck in for proper (and cheaper) diagnosis.

Bighouse

I got plugs, leads and an airflow sensor for 160 pounds which is about $300. The plugs deifinitely have not been done since I have owned the car from 40k miles - it is now on 82k so I thought that would be worth doing anyway.

My local dealer (in the UK) charges about $130 per hour labour so a couple of hours labour would almost cover the cost of the parts I have bought and then I would have to pay the dealer's prices for any spare parts...

I'm hoping the bits i've bought will fix it

Pottie

It s easy if you have extra bucks to burn in dealer...
Get the OBD cost around $200 and is worth it for long run and it ll tell you what s wrong and compare those with the list of diagnosis that post it in forum.http://www.whnet.com/4x4/dtc.html.
we all know here MAF in ML is one of the defect material..if you could fix it u re self why bother to spend extra for same result..
as for the plugs...is a good idea to replace them all and also check the wire it self...then should be runnin a champ again...Good luck..

Bighouse

Thanks for your help guys. I fitted the new airflow sensor today and its like a new car. It is so much quicker and is giving me full power just as it should. I have not fitted the plugs and leads yet so the problem was difinitely the airflow sensor. Im not going to fit the the plugs for a while - its running so well now I dont want to touch it!

By the way it was only the in line plug in sensor that I replaced that is just by the air filter box, only took 5 minutes to do the job and only cost me 50 pounds (about $100). Bought it from an online parts distributor. This has saved me spending a load of money at the dealers, great result.

Pancham

in line plug in sensor ? What is that? I never see that in my 2000 ML320 (USA version) ... Can you please explain.

Thanks.

roberthelfrick

Probably refers to the MAF sensor insert.