please help my ml has no power??????????

[rob (i hate my ml)]

dont know if anyone can help but have just been out in my ml270 51 plate and have found a serious? problem or hopefully not so serious.i do not seem to have any power it is an auto with tiptronic box seem to have lost my kickdown and the engine will not rev over 3000 rpm even in neutral or park , tried shifting into tiptronic but is the same will not rev over 3000 rpm anyone else suffered this, anyone got any ideas or suggestions as to what problem might be apart from a costly trip to ridgeway thanks.

 

[delboy777]

MAF perhaps ?

 

[rob (i hate my ml)]

sorry am not very technical can you explain what maf is please

 

[HERBIEMERCMAN]

i agree with delboy could be the maf ( max air flow sensor ) try unplugging the connector see if it improves things. it is located just after the air intake filter unit. also i had a loose turbo boost pipe which reduced the boost pressure, the pipe was still located in the air intake manifold but the joint was leaking. boost pressure controls the fuel pump and ecu. etc. herbiemercman.

 

[rob (i hate my ml)]

hey have just been out there is the maf what looks like a ball on the drivers side of the engine compartment if so have just took of the 2 little pipes and this seemed to make the problem better what would be needed as a permanant repair if this is the problem also if anyone knows what the dial on left hand side of engine is it has 75% and 100% written on it could they please tell me thanks

 

[Cole@MBS]

Thats telling you how clogged up the air-cleaner is!!

 

[HERBIEMERCMAN]

the maf does not have any pipes attached to it, it is an electronic sensor measuring minute pitot tube pressures and micro currents, this controlls the fuel injection and engine / autobox management via the ecu ( electronic control unit ).it usually has a 5 pin plug attached to the tube directly after the air filter box. herbiemercman.

 

[escapedfrombache]

Have you fixed it?

Hi,

I've had the same problem with my ML, which is suposed to have a new MAF in it, won't rev over 3000. Did you cure the problem?

A

 

[Cosworth]

Mine had the same problem and it was cured by changing the MAFF. The electrical part between the air intake and filter.

 

[power-steering]

Agreed. Look for your air filter box and behind that box will be your connection the air intake piping.. like a big thick black tube which runs back to the engine (back to intake manifold) to be precise. Along that black tube you will have another unit between your air filter box and the black tubing.. this will have the electric sensor connected with an electrical plug.

If you disconnect this, the revs might "hunt" up and down.. i.e. not stable but see if you are now able to rev the engine past 3000rpm. It is a common fault for these to go, try taking the MAF off from each end and blowing it out.. sometimes a simple clean will fix the problem but otherwise it may need replacing as everyone has stated.

If you've got a blower, blow it out.. spray some carb clean inside and blow it all out again.. then reconnect it, connect the plug back on and see how it runs.. fingers crossed it should cure it if no damage is done to the actual sensor inside.

Good luck,
Jay

 

[piestore]

Ml wont rev

Hi

270 cdi when in park or N should not rev over 3000 as it is rev limited at stand still it needs to see a speed signal to rev any higher, However if the engine doesn't produce power and won't rev over 3000 while driving it is possible that the engine or gearbox is in emergency mode. Fault code should help to identifythe problem, below listed common faults, most common first
1 MAF sensor (mass air flow sensor) fault code usally with a lot of black smoke
2 boost pressure fault (can be boost air leak or blocked exhaust or vac fault to transducers)
3 gearbox speed sensor fault ( fault code and speed sensor reads 8000rpm in actual values) new electrics kit required
4 low ATF in gearbox due to leak at pilot bush

 

[Mark A]

I agree it will be the MAF. Only buy from MB (+/- £60) as some of the others don't work. I tried disconecting the plug on my MAF and didn't see any improvement, but bit the bullet and changed it anyway - a totally different car was the result.

Mark

 

[psmart]

Hi

270 cdi when in park or N should not rev over 3000 as it is rev limited at stand still it needs to see a speed signal to rev any higher, However if the engine doesn't produce power and won't rev over 3000 while driving it is possible that the engine or gearbox is in emergency mode. Fault code should help to identifythe problem, below listed common faults, most common first
1 MAF sensor (mass air flow sensor) fault code usally with a lot of black smoke
2 boost pressure fault (can be boost air leak or blocked exhaust or vac fault to transducers)
3 gearbox speed sensor fault ( fault code and speed sensor reads 8000rpm in actual values) new electrics kit required
4 low ATF in gearbox due to leak at pilot bush

I dont know if they changed the design, but an 11.00 270cdi ML can freely rev in Park or Neutral upto the ~4500rpm limit. When the MAF on mine was disconnected, the car ran perfectly except lacked 'urge' in acceleration and drank more fuel.

On this engine, so many things can cause the 3000rpm limit as I found during testing/diagnostics. MAF possibly, but if you disconnect it and it still hits the 3000rpm limit, then look elsewhere (again, Im quoting from an 11.00 engine, they may have changed on the facelift models).