270 cdi ml

[Jopppop]

My 270 CDI ML feels like it's missing at about 2500 RPM, It's worse with a load. It's fine below and above this RPM. Had a new MAS and two new cats. No errors showing on the diagnostics ??? Any ideas please.

 

[BenzedUP]

What do you mean missing 2500rpm? have you took it to merc? what does mercedes think?

 

[Jopppop]

Hi, thanks for the reply. At about 2500 RPM the engine surges as if it's misfiring and the rev counter fluctuates between about 2200 and 2700 RPM, I have to drop it down a gear on the tiptronic or use kick down. Its annoying because its at about 70 mph cruise speed on the motorway. My local independant merc garage has checked it and can find nothing wrong.

 

[BenzedUP]

Hi, thanks for the reply. At about 2500 RPM the engine surges

I think thats the turbo kicking in? they usually kick in at about 2k

Have you tried flushing the ECU or even updating the ECU or gearbox software?

Somebody on here must have some idea..?

 

[lynall]

Still shouldnt surge though, if it wasnt likeit before, then its a new fault on a current car something has obviously gone wrong, have you checked all wiring and piping under the engine cover?

Not sure of merc specialist but cant be much cop if they said nothing wrong and let you go especially if they test drove it and felt the hesitation.

All levels okay?



Lynall

 

[Jopppop]

Thanks for the replies. Never done anything to the ECU. I've had the ML for about 2 years now, the fault has always been there... I have checked under the engine cover, all looks okay. levels all okay, gearbox ATF level check is sealed, so I can't check it... When I had the MAS fault, my local independant garage diagnosed it using STAR, after the MAS was replaced, the faults were cleared down and I was told all was fine. I'm near Rochester in Kent. Cheers. Graham.

 

[panason1c]

jopppop

Sounds like you are describing the difference in rpm from cruising at 70 with little use of accelerator to then applying more throttle.....it is 'normal' for there to be approx a 500 rpm difference (similar to a slipping clutch situation in a manual)

These auto boxes dont seem to 'lock up' as solidly as other make auto's do and a 500 rpm 'slip' between throttle on and throttle off is normal.

 

[lynall]

I think iirc theres a bloke in maidstone whos meant to be good name of steve, do a search on here for his contact details.



Lynall

 

[Jopppop]

Thanks for all the advice. I have had STAR diagnostics completed recently, but shows no errors. It's when using cruise control at 70mph, it revs at about 2500 RPM, any slight incline, the engine speeds up to keep the speed constant and that is when it starts to surge and feels like it's missing...

 

[rpe2]

Saw similar symptoms on a C class last week. Blocked cat.

Richard

 

[Jopppop]

Thanks for the advice... Just got back from a trip of about 400 miles. The ML still has a flat spot at about 2500 rpm wher you can feel the car surging. It's had two new cats and a new MAS and has been to the garage and checked on a STAR diagnostics with no faults found... I'm getting tired of this problem as it's right on the 70 mph speed with cruise control engaged. Any further help much appreciated.

 

[jimmymidnight]

i think you are describing the same problem my family are having with out ML270, when you accelerate, when the revs build up, sometimes when it goes to change gear it jumps up the revs dramatically, like it missed a gear, and then falls into the correct one...

 

[Buggerlugs]

Could be the torque converter lockup clutch shuttling on and off, you need another star test with someone monitoring the converter clutch duty cycle to confirm or dismiss this.

 

[mustang]

ml 270 auto box problem

hi all. i have a prob with my gear box on a 2001 ml 270 as decribed below . any ideas ?? thanks

i think you are describing the same problem my family are having with out ML270, when you accelerate, when the revs build up, sometimes when it goes to change gear it jumps up the revs dramatically, like it missed a gear, and then falls into the correct one...