ML power loss . . .

[Dee James]

My ML270 has the dreaded power loss issue where it won't rev passed 2k turn it off and restart and it's ok for a while. I've already changed the MAF as I couldn't find any mention in the service history of it being replaced but it's still doing it. Following (good) advice I am going to scan it to see what it throws up before I spend anymore money but in the meanwhile has anyone seen this fault happen intermittently? On the sticky regarding this it says check fuses - any ideas what ones?

 

[Bobby Dazzler]

I've read that replacement MAFs can be faulty. It's unlikely, but possible. Could you ask the vendor if you can try another, just to eliminate it?

 

[grober]

http://www.mbclub.co.uk/forums/new-member-introductions/183620-new-forum.html post 6

There will be a 12volt supply to the MAF together with a 5V reference and return. I assume the 12v supplies the heated element -- if its fused?????
http://www.mbclub.co.uk/forums/engine/11188-testing-maf-dummies.html

 

[Dee James]

I've read that replacement MAFs can be faulty. It's unlikely, but possible. Could you ask the vendor if you can try another, just to eliminate it?

If my scanner I've just ordered shows up a MAF issue that is exactly what I will do

 

[Dee James]

http://www.mbclub.co.uk/forums/new-member-introductions/183620-new-forum.html post 6 There will be a 12volt supply to the MAF together with a 5V reference and return. I assume the 12v supplies the heated element -- if its fused????? http://www.mbclub.co.uk/forums/engine/11188-testing-maf-dummies.html

F11 looks worth checking . . .

The fact it happens then is ok after a restart made me think the MAF was at fault somewhere but worth checking the fuses again and having a read up while I wait for the scanner arrives, obviously it's no substitute for STAR but hopefully will clear any stored codes and point me in the right direction

 

[Dee James]

Just hoping it's not the swirl flaps/inlet manifold, I could do without that expense just after Christmas . . .

 

[EinGV]

I had intermittent power loss (limp mode) on my 2009 C Class automatic for several years, getting more and more frequent and happening in different conditions. No error codes ever came up, main dealer had two looks, independent also looked, neither could find the cause. I wrote a threatening letter to the main dealer and demanded they picked-up the car (hoping it would go wrong while they were driving it) to take another look. Luckily it did happen while they were driving it and they managed to sort out what it was - auto box control unit. That was a couple of years ago and the problem has never recurred.

 

[Dee James]

I had intermittent power loss (limp mode) on my 2009 C Class automatic for several years, getting more and more frequent and happening in different conditions. No error codes ever came up, main dealer had two looks, independent also looked, neither could find the cause. I wrote a threatening letter to the main dealer and demanded they picked-up the car (hoping it would go wrong while they were driving it) to take another look. Luckily it did happen while they were driving it and they managed to sort out what it was - auto box control unit. That was a couple of years ago and the problem has never recurred.

I've had two codes, one relating to low boost pressure one to an open circuit now cleared, time to call an Indy I think . . .

 

[gIzzE]

If you can get the plug off the swirl flap motor you can put a 4.7K ohm resistor over the two wires and if you stay out of limp mode you know it is this.

 

[Dee James]

If you can get the plug off the swirl flap motor you can put a 4.7K ohm resistor over the two wires and if you stay out of limp mode you know it is this.

I think it's the cats, there's a fair bit of noise coming from underneath now and it's going into limp mode all the time. Swirl flaps are moving ok the bar is still connected and I've swapped the transducers to rule that out.

Wish your ML was up for sale when I was looking, all the hard stuffs done!

 

[Dee James]

Update: it was the cats, both replaced today - running much better than it has in my ownership, feels much quicker off the mark