ML 270 CDi won't rev past 3000rpm.

[escapedfrombache]

Hi guys,

Don't know where to start it's been a long storey.

I have an 2000 ML 270 which I bought as salvage and repaired. Post repair it had a couple of gearbox issues, they were resolved by a gearbox specialist and as part of the repair they changed the MAF.

The car drives fine, or so I thought, if you really floor it it cuts out at about 3200rpm. Not nice on the M6. Anyway I had not been able to change the fuel filter as the housing was broken. So I've done that and now it doesn't cut out suddenly but appears to hit a rev limiter about 3200rpm.

If you hold the throttle open when stationary the engine acts just as if it was on a limiter.

Any suggestions or things to look at. All help appreciated as the wife would like to drive the car.....soon.

 

[television]

The cars will cut while in N ,thats normal have you tried driving it again

 

[escapedfrombache]

ML cutting out

Yes, It still does it when driving, it revs clean as a whistle to 3500 and then the revs cut suddenly to about 2000 and then it will go again.

 

[television]

Hang on until one of the techies come on and see what they say,,its a quiet day today so far

 

[stumo]

Yes, It still does it when driving, it revs clean as a whistle to 3500 and then the revs cut suddenly to about 2000 and then it will go again.

This description seems a bit odd, was this in "D" or what?

It will have a rev limiter in "N" and "P" as was pointed out before, but on these diesels that should just hold it at a certain rpm, not like a petrol where it can bounce off the limiter.

So you really need to test it in gear... When you floor it in "D", it will change gear at 4000 max, so 3500 is in that ballpark. So what happens if you hold it in say "2" on the gearbox and then try going past 3500?

 

[escapedfrombache]

If I put it in 2 and rev it on it only gets to 34-3500 and the same thing happens, it hits a brick wall and the revs drop back to 2000 and then it will accelerate again.

Could it be fuel supply? or blocked cats? I have read about allsorts of different problems like this.

It really feels like a sort cut limiter intervention, as iff the fuel pressure just disappears.

 

[stumo]

That is a weird problem. From my (limited) experience blockages and fuel starvation on diesels don't manifest themselves like that, they just won't go past at a certain rpm. So something is really cutting out on yours, and then resetting once rpm drops to 2k.

I would get the codes read if you haven't already. Other than that I'm all out of ideas.

Please keep us posted when you do find the probblem.

 

[psmart]

This could all be down to the air-induction system. My experience whilst working out a fault on my own system showed that if the Turbo was disabled, then you wouldnt get above 3000rpm, primarily due to a lack of air, and as noted the engine would freely rev in N or P.

Been a salvaged car, could be that something has got cracked, for example the vacuum reservoir or a crack in the vacuum pipes (tiny). If you get the fault codes read, could probably help some more, but a simple test is to pop the bonnet, left hand side is a large golf ball (Vacuum reservoir), just pull the pipe out which goes to the turbo control valve (two pipes on the top, and a fuel filter type device hanging from the bottom). Make sure to block the disconnected pipe so crap isnt sucked in and the vacuum can still build up. Now drive around and see if how the car responds is similar to the fault your seeing, ignoring low end acceleration.

 

[Xtractorfan]

If you have properly fixed the fuel filter housing and it aint leaking fuel or letting air in I would buy a new maf from Mb..the genuine article and fit it..

 

[psmart]

If you have properly fixed the fuel filter housing and it aint leaking fuel or letting air in I would buy a new maf from Mb..the genuine article and fit it..

The MAF doesnt make much difference regarding general power. When I was running around with the diagnostics plugged in looking for gearbox issues, I disconnected the MAF and you still had full power available, just more thirsty and not as quick or smooth acceleration. I installed a new MAF as the old MAF was giving some wierd readings and it basically improved smoothness, economy, top end and acceleration.

 

[escapedfrombache]

Hi,

Tried PSmarts idea with the vac off, and get the following. Very flat all round, won't pull and won't get past 3000rpm even in N.

I'm going to question the source of the MAF fited and see if it's spuriarse.

Fuel filter not leaking fuel or air.

 

[BlackC55]

This sounds like an inlet port shut off issue.

Have you had the fault codes read?

 

[psmart]

My ML revs freely past 3000rpm in N/P when Turbo disabled, so sounds like another issue, not had the experience of the inlet port shut-off breaking but from what Ive read, is very plausible. Also another test I made was a blocked exhaust gave a similar effect, so this would tend towards inlet or exhaust restriction. Go for BlackC55s suggestion, get the codes read to confirm. Strange that an accident could have left damage to inner parts,what kind of impact did the car suffer?

 

[Monio]

Hi all
I have a similar thing in the same car ML CDI 2000year, RPM on n/p is ok, but on the "D" car drives up to 40 MPH and 3000 RPM not even one mile further. This sounds like an emergency gear or sth like that. Probably we need to plug the comp to get fault readings.
Anyway have u ever heard about an emergency gear which is on after car was involved in accident?


p.s.The RPM in my car doesn't rev to the 2000. If I drive it and keep holding my foot maximum down on the accelerator it goes 40 MPH and has fix RPM of 3000.
Car was also hit in the right side badely.
Any clues?

 

[escapedfrombache]

My car had very light damage, I think the engine problems were there pre-accident.

How do I look at/check the inlet flaps?

I had the stuck in safe mode problem with mine post accident. I had it sorted by a gearbox specialist in Prerston.

 

[digitalgalaxy]

I have a 2001 ML 270 which started doing the same thing yesterday. Prior it was very quick for it's size now it gets to 2k revs and changes up gear. It won't kick down and even if you use the tiptronic it struggles to 3k then its like it hits a rev limiter. It briefly went back to normal for about 30 secs then no go again.If you find the problem let me know or its of to MB specialist for me.

 

[tonychunk]

Try a high rev leak off test. Could be an injector.

 

[BlackC55]

It won't be an injector problem.

get it on a Star first to be diagnosed. It will save you money in the long run

 

[kebo57]

Hi guys,if you really floor it cuts out at about 3200rpm.

Hi do you get the engine warning light on the dash when it cut out & when you back off light goes out then it ok untill you floor it then its cuts out again.


Kevin

 

[andrewswe]

No light, it just does the cutting out.

Has plenty of warning lights on most of the time.

Did get better with recon injectors, but still not right