OM642 POWER PROBLEM

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tode

Active Member
Joined
Aug 13, 2011
Messages
484
Location
NW FRANCE
Car
S350 Bluetec
Good morning all.
I have a W221 with the OM642 engine which has given no particular problems in the last few years, but while on a trip yesterday, while cruising at 70 mph I started to notice that the revs were much higher than usual (2400 instead of 1500) - I thought maybe doing a regen, but a few minutes later I could still maintain speed, but there was no reaction when I tried to accelerate (to overtake). Even foot flat on the floor, no increase in revs or speed. No EML. Rather worried, as I had 200 miles of motorway ahead of me !
After 5 - 10 minutes of this, I pulled over, switched off, and waited 5 minutes. Switched back on and set - no problem, back to usual.

A similar thing happened two years ago, but then it lasted two hours and when I took the car into Mercedes, they found nothing - no fault logged under Star.

Has anyone got an idea what's happening? Batteries fine and servicing up to date, no other problems . .

Thanks in advance.
 
I think that the problem will occur more frequently and at that point a fault code will probably be triggered,
Could be , turbo actuator , swirl flaps/inlet port motor , exhaust back pressure sensor as regular suspects.
What mileage are you on buddy ?
 
Just over 75000 miles.

Actually, it's not catastrophic, since the car still manages 60 -70 mph, but it occurred to me that if it can get stuck in "minimum" position, could it not happen also in max position ? Which may have a different outcome ?
 
Just over 75000 miles.

Actually, it's not catastrophic, since the car still manages 60 -70 mph, but it occurred to me that if it can get stuck in "minimum" position, could it not happen also in max position ? Which may have a different outcome ?
The car being limited in speed is because it’s in Limp Mode due to a fault and restricted to <3000 revs
 
I had a real issue with my om642 the last couple of months, it would go into limp mode with no codes (at 2 or 3 week intervals) just for the one trip.
I would go to work, turn the engine off and when I got back in a few hours later all was well.

After about 6 weeks of this it started to become an issue every other day and then always in limp mode.
It took 6 trips for the code to show up, once the engine light had come one I could find it and it was a turbo issue of some sort.

So as someone already said, boost sensor, egr, turbo actuator or stuck veins in the turbo.

I removed the turbo actuator and it looked bad inside so I got a new one..........still an issue.
Cleaned the egr out........nope.
Cleaned the boost valve sensor tube and replaced the sensor with new genuine part........nope.

I then sat and tested the wiring and found it to be a heat related issue with the actuator plug.

All was well if the engine was cold and you removed/attached the plug to the actuator before driving. Once it heated up it was no boost and limp mode.
I cut the plug off and soldered a new one on, all is working again as it should an no issues for 1500 miles

I hope this may help

Si
 
As above, could be heat related after the temperatures for tge last few days.
 
I've had limp mode (with and without the EML on) from a variety of causes including the DPF pressure and temperature sensors, MAF sensor, EGR valve, and turbo issues. These issues started at around 90k miles but mostly couldn't be cleared by turning off & on again.

The dealer was 15 miles away down the M4 motorway ... as mentioned one advantage of the OM642 is that it still has enough power in limp mode to (eventually) cruise at around 70 mph - I got plenty of practice at this!

Hope you are able to get yours sorted quickly.
 
Thanks for the advice - I(m looking at whether I'm capable of pulling the actuator apart . . .and putting it back together again ;)

Can you get to everything? I had to have the exhaust manifolds and turbo replaced on mine - engine & gearbox out. The manifolds have a liner that can delaminate, dropping bits of steel into the turbo. It's a 'known issue' but not that common ... I've mostly heard of it in MLs (huge numbers of them with the OM642, unlike the Vito).
 

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