Mercedes ML270 CDI slow and gutless

[MontyC]

My Mercedes ML270 CDI is very slow and slugish whilst driving and wont rev above 2500rpm and go above 85mph, and struggles with hills , when parked in Neutral it revs up normally so is only happening whilst driving any ideas?

[ManFromDelmonte]

Sounds like some kind of Limp Home Mode, could be engine or gearbox but I would guess gearbox.

It would be worth doing a bit of googling around this but you might not like what you read.

[MontyC]

ManFromDelmonte said:

Sounds like some kind of Limp Home Mode, could be engine or gearbox but I would guess gearbox.

It would be worth doing a bit of googling around this but you might not like what you read.

I have done some googling but it comes up with so many different things. I have cleaned out the EGR valve, given it a full service changed fuel filter I know its not the MAF sensor as it revs fine in neutral I think it is in limp mode but there are no lights up on the dash .

[MX-5 Lazza]

Sure it isn't a seized brake? Is it better in lower gears?

[MontyC]

MX-5 Lazza said:

Sure it isn't a seized brake? Is it better in lower gears?

Hi no checked all the brakes are fine, its an auto wont rev above 2-2500rpm whilst driving although fine if your just sitting in neutral and rev it up, so guessing its not the turbo or waste gate.

[longblackcoat]

Sounds like EGR to me. You may well have cleaned it out, but the system still thinks there's a problem. My GL did precisely the same; replacement was required, I'm afraid.

Get it on the diagnostic machine and it'll tell you one way or another.

[MontyC]

longblackcoat said:

Sounds like EGR to me. You may well have cleaned it out, but the system still thinks there's a problem. My GL did precisely the same; replacement was required, I'm afraid.

Get it on the diagnostic machine and it'll tell you one way or another.

The thing is no dash warning lights have come on so I'm not sure it would even bring up a fault code?. And if it was the egr valve like air mass I wouldn't of thought it would Rev up fine in neutral but may be wrong

[longblackcoat]

MontyC said:

longblackcoat said:

Sounds like EGR to me. You may well have cleaned it out, but the system still thinks there's a problem. My GL did precisely the same; replacement was required, I'm afraid.

Get it on the diagnostic machine and it'll tell you one way or another.

The thing is no dash warning lights have come on so I'm not sure it would even bring up a fault code?. And if it was the egr valve like air mass I wouldn't of thought it would Rev up fine in neutral but may be wrong

No lights showed up on mine, and it revved higher in neutral than on the road. Driving it was as though the turbos weren't boosting at all. The STAR machine picked it up straight away.

If you're anywhere near Milton Keynes get over to Autoclass and they'll give you an honest opinion.

[tobinen]

As above, have it plugged in to STAR and stop the guesswork. It's in limp-home mode for a reason.

[SLacKer]

When this happened to my W164 320 CDI it turned out to be the turbo vanes sticking. I could drive around the problem but if I gave it a little to much accelerator especially when cold it would go into limp mode. A turn off and on again cleared it.

I have a normal code reader and got codes relating to the waste gate actuator

http://www.pistonheads.com/Gassing/topic.asp?h=0&a...

Once I got the vanes cleaned up the car has returned to normal.

I never got an engine light either.

[MontyC]

Well after plugging it in I ended up with fault codes
P1187 Rail Preasure monitoring
P1470 Boost Preasure control
P0115 Coolant Temp Sensor

So the main Problem is P1470 but unfortunatly this could be a number of things and involves possibly removing the inlet manifold

[Qwaszx11111]

Hi. Mine is doing the same. Did you ever get this fixed, what was the problem? Thanks

[daemon]

Qwaszx11111 said:

Hi. Mine is doing the same. Did you ever get this fixed, what was the problem? Thanks

I think you'll need to plug in a code reader and read the codes as a starting point. The odds of your problem being identical in cause to his are low.

[stuarthat]

Mine was cats failed , caused by bad injector ,so get both checked .

[GlenMH]

My 320CDI did this (and revved well in neutral) but needed a new MAF to sort out.

[philcray]

my 2003 ML270cdi had a similar sounding problem, would not go over about 75mph. Had it checked out and replaced faulty MAF sensor, been fine since.

[Sparx12345]

Will be interested to hear the results of this. I seem to have an occasionally similar issue; once in a blue moon I start mine and for a while it just won't bite, feels totally sluggish. If I turn it off then on again (lol) then it's usually ok.

Although, embarrassingly, the first time I had a similar problem I realised I'd accidentally nudged on the cruise control and it wasn't letting me go over 10mph. That was a red face...