Help Needed for ML270cdi loss of power

[Argenjagd]

Since ten days ago my ML270 cdi, 2001, 93.000Km do not deliver his full power. No warning lights on.
Sometimes, it runs at normal performance during a sort period, but after 10 to 30 minutes it slow down to 2500rpm and 130km/h.
I have already checked fuel filter, air filter, catalitic converter, air intaque valve, turbo valve, fuses and conections, everithing works properly.
I could'nt find the fuse F24/8, 7.5A, who controls the Diesel Engine Control Unit wich is supossed to be under the lid of the second E-box.
Can somebody help me??
Dealer with electronic failure detector is far from home (I am living in a town from Patagonia)
Also, where can I get a Service Handbook for this vehicle, the Operator Manual is useful for nothing.

 

[jberks]

Hi,
It sounds like the ECU is going into get-you-home mode. Could be the old Air mass sensor again or could be one of several other things. Difficult to say without a diagnostic. On 2000- MBs I don't believe there are any warining lights when this happens.

 

[piestore]

cdi emergency mode

hi

Would have to agree best bet is air mass meter

 

[garygazza]

F24/8 Wot An Ass To Find!!!!!! Once Found Never Forgotten Trust Me.where The Engine Compartment Fuse Box Is Located You Will Find A Panel Held With Screws.remove This Panel And You Will See The Engine Control Unit And A Birds Nest Of Wiring.at The Rear Of This Box(still Difficult To See)is A Single Fuse Holder Conaning A 7.5 Amp Fuse.this Is The Elusive F24/8.good Luck That Took A Couple Of Hours To Find So It Will Never Be Forgotten.

 

[c250 turbo diesel]

Answer

Patagonia, is high up I guess, have you checked the alitude compensation thingy is working ? had the same problem once in the Andes !

 

[timhammond]

I have the same problme with my ML270CDI 2001

Hi. My ML270cdi has exactly the same problem
How did you fix it?

thanks for any help and guidance on this

Tim

 

[jberks]

Have you has the fault codes read? As above - normally the MAS sensor

 

[timhammond]

not yet
guess paying for this first is the best solution - I just wondered how the chap from Patagonia solved his

 

[psmart]

Hi All,

JBerks could be right about the Air Mass sensor, but if you read my other posts, you will find I have had this problem due to the Turbo Boost Pressure Transducer. If this device cannot control the vacuum to the Turbo, then the ECU disables control of this device and you engine becomes a normally aspirated engine, with a rev limitation to 3000rpm.

My problem is a minute leaking Turbo to Primary Catalytic converter seal, which is heating up the engine bay and filling it with unburnt carbon particles, which are clogging up the Boost Pressure Transducer atmospheric pressure air filter.

If you want to discount my experience, look into the engine bay, left hadn side, you will see a metal cover above the exhaust manifold. Either use a mirror and torch, or put your fingers behind this shielding. If you see soot, or your fingers are completely black, you have the same problem as me. I havent had time to replace the seal yet, so I cant advise you on the procedure.

 

[jonny2]

Hi, I've a similar problem in that when driving the turbo boost is lost until the ign is off for about 5 seconds. MAF/MAS usually give these symptoms & boost probs when the engine is under load and the power is suddenly lost. Like a madman I immediatley replaced the MAF sensor and guess what, I still have the problem. With my ML its fine providing you drive hard and need boost, as soon as its allowed to cruise and back of the gas all boost is lost until engine is restarted. Not had chance to code read it but now think its more to do with the boost pressure transducer,, Would love to get anyone's opinion., When getting desired boost there is quite a bit of air noise, sounds like a split or leaking hose but cant find any problems and no loss of performance.. As long as I got boost when I want it then I'll be happy.

 

[ndaist]

Hi there

I'm having the same problem with my 2003 ML270cdi. Did the problem stop when you changed the seal or was it something else?

Thanks.

Hi All,

JBerks could be right about the Air Mass sensor, but if you read my other posts, you will find I have had this problem due to the Turbo Boost Pressure Transducer. If this device cannot control the vacuum to the Turbo, then the ECU disables control of this device and you engine becomes a normally aspirated engine, with a rev limitation to 3000rpm.

My problem is a minute leaking Turbo to Primary Catalytic converter seal, which is heating up the engine bay and filling it with unburnt carbon particles, which are clogging up the Boost Pressure Transducer atmospheric pressure air filter.

If you want to discount my experience, look into the engine bay, left hadn side, you will see a metal cover above the exhaust manifold. Either use a mirror and torch, or put your fingers behind this shielding. If you see soot, or your fingers are completely black, you have the same problem as me. I havent had time to replace the seal yet, so I cant advise you on the procedure.

 

[Blakey]

Almost certainly going to be loss of vacuum boost pressure, which will invariably mean a small leak on the vacuum circuit. This happened to me and was solved by applying some amalgamating tape to a split in the turbo actuator pipe to my c220.

To diagnose, take the vacuum hose connector off the boost vacuum transducer and suck on it. If you draw air up, then there is a leak in the circuit somewhere which should be fairly easy to locate. If you can't draw air up, then it's probably the vacuum transducer itself.

Good luck, - when you've solved the problem, it'll feel like a new car!

Chris.

 

[stumo]

I agree with Blakey - suspect vacuum and/or transducer problems.

I don't have this problem on my '02 ML (yet) but I had a wee play around with the vacuum pipes recently. I was actually seeing if I could disable EGR by blocking the vac pipe at the EGR transducer (which is an identical/interchangeable part to the turbo transducer).

Anyway, by blocking the pipe it made the turbo spin down at idle - usually it still spins quite a bit. This made accel from standstill to be non existant, and some funny noises, until after a few seconds the turbo kicks in and we were off, running like normal, until the next stop. Note this was the EGR transducer I was playing with, so obviously there is some interaction between the EGR and turbo systems, probably somethng to do with the variable geometry part of the turbo as that can be used to assist EGR.

Normally a common thing to try when you suspect one of the 2 transducers is to swap them over, but now I'm not so sure.

Anyway, I hope this spiel somehow helps.