Performance problems

[Griffo]

I have a 2000 W21 E320CDI. Yesterday, when on the return leg of a 30 mile round trip, I found that the car wouldn't kick-down and I only had mild acceleration. It failed to change down going up a long hill as well.

When moving off from junctions, it changed up OK but only with mild acceleration. There were no warning signs on the dashboard.

We stopped for about 10 minutes at a shop near home. Upon re-starting, it seemed to have cleared, accelerating OK and kicking-down when asked. There was a fair bit of black smoke when accelerating hard (have noticed this lately).

Suggestions please folks?

 

[television]

I think the MAF get one from Bosch service center if Bosch

You could unplug it to test

 

[Griffo]

Thanks for the reply Malcolm. Excuse my ignorance but where is it located and what does it do please?

 

[Griffo]

I found a thread in the engine forum, about cleaning the MAF. I think I have found mine, it's nestling under the edge of the plastic engine top cover, which has to be removed to gain access to the MAF. I presume this is the MAF? It has a number printed on the flange - 24550790S1. Inside it has other numbers - A611 094 00 48 and PBT GF 30.

I removed it, didn't look dirty. Gave the housing a wipe round and out it back together. Went for a run - no kick-down, so stopped for a minute. Re-started, still no kick-down, so stopped again after a couple of miles. Gave it a minute and re-started - kick-down working again! However, still lots of black smoke when I accelerate hard.

Malcolm, you mentioned I should try with the MAF disconnected - what should I expect to happen if I do this please?

 

[panason1c]

Disconnecting the maf will give you what you have now ie = no kickdown and little or no turbo response...so, not really telling you anything........

It does sound like a maf problem .....the black smoke is probably just a build up of soot in the exhaust system during your current problem and should clear up after a good 'blast' once the initial problem is resolved......maf

 

[Griffo]

OK thanks, looks like the MAF is the culprit. Can anyone suggest the best place to buy one please?

 

[panason1c]

OK thanks, looks like the MAF is the culprit. Can anyone suggest the best place to buy one please?

Buy one either from MB or a Bosch agent but definately NOT off ebay, there are many cases where some ebay mafs are duff.

 

[len_merclover]

Hi Griffo, I had the same problem last week. I was told it was a turbo issue and it need replacing.....bet you know how I felt then! sick!!! Anyway, after much advice from other members on here I was advised it was the mass air sensor (cost £70) - got this changed and it's fine now!

Hope you get it sorted - it's rather worrying when you want to pull away quickly knowing it may not 'go'!

Len

 

[panason1c]

Hi Griffo, I had the same problem last week. I was told it was a turbo issue and it need replacing.....Len

Just out of interest, was it a MB garage that told you it was a turbo issue?

 

[Griffo]

Hi Len,

I'm glad to hear your problem was easily solved.

I have ordered a new MAF sensor from a Bosch retailer - £42 + VAT, which seems very reasonable. The MB dealership quoted me £63 + VAT. When I mentioned I could get a Bosch unit for £42, they admitted that MB buy them from Bosch, then sell them to the Dealerships, who then sell them to us!!

Anyway, it should be here on Wednesday, so I'll report back as soon as I've fitted and road tested it - fingers crossed!

cheers.

 

[len_merclover]

panason1c: I called out Mobilo whom said it was the turbo unit! Since replacing the MAS it's been fine. I have alos noticed an increase of some 5 mpg!

Amazing what one tiny little thing can do to that big engine a!?

Griffo: Yes I was over the moon! having just got the car I felt sick! it's one of these thing's you think will happen to you when you have bought a car and it did! Anyway, I also hope it's this MAS for you too, it was easy to fitt also. I was advised by a member her to start with this is it was mostly the part what caused my problem.....please update as and when would be intresting.... if it is I wonder why MB haven't added this part to a service!?

len

 

[panason1c]

"panason1c: I called out Mobilo whom said it was the turbo unit! Since replacing the MAS it's been fine. I have alos noticed an increase of some 5 mpg!"



It's worrying that Mobilo diagnosed a turbo problem when they, of all people, should be aware of symptoms of maf failure....i wonder how many turbo's have been replaced when the problem was a duff maf?

 

[len_merclover]

Absolutely, I agree totally. I was just thinking this after having it replaced. You know, after even having it replaced, the next morning I was very anxious before driving off – as I drove away, seemed ok, even as I passed the usual spot where it use to ‘limp’ I was still thinking maybe it is a fluke, might do later (thinking the start machine was correct)....... so, from my first experience with MB techi, I’m shocked to say the least not like the turbo is near the price of a mas is it.....jus some 1500 more!!!

 

[Griffo]

Fitted the new MAF sensor this morning and went for a test drive. Guess what - no damn difference! All the same symtoms. In fact, having stopped and re-started, getting 'normal kickdown' function and turbo back (with attendant black clouds behind!), it then went back into limp mode a couple of miles on.

So I need further help please?

 

[panason1c]

Sorry the maf didnt fix it, possibly a turbo pressure sensing sensor (located at the top of the intercooler on the n/s) is faulty, but then it could be a number of things!, i would go to another MB specialist for a second opinion.

 

[len_merclover]

Hi sorry also. Did u try mass air sensor which goes into the maf?

 

[Griffo]

It was the MAF sensor that I changed.

 

[panason1c]

Hi sorry also. Did u try mass air sensor which goes into the maf?

'mass air sensor' and 'maf' is the same item, some call it one or the other.

 

[panason1c]

It was the MAF sensor that I changed.

Hope you didn't buy it off ebay?........there are many stories of duff maf's being sold on ebay.

 

[JEZ.S320L]

Hope you didn't buy it off ebay?........there are many stories of duff maf's being sold on ebay.

I can vouch for that Lesson learnt :-?