ml270 wont rev

[rooby_roo]

hi all, i bought this ml270 today for my wife from a bca auction, it was a direct ford part x so thought it should be ok, and as for the 70 miles journey home i thought it was money well spent, it drove like a dream, up and down the gears fine, no problems,
But then when i came to start it again after i got home the problems began, it struggled to start when warm, 10 seconds of turning over before it fired up, then as i was driving it i noticed the gearbox wasnt kicking down and it seemed a little flat, i put it into tip and it went up and down the gears ok but was still flat, like it was in limp mode, i stopped and revved it in park and it wouldnt go over 3000 rpm, but then all of a sudden it would, but as i pull off it went back to not revving again, its hit and miss, one minute its going like a dream then the next its really flat . any ideas guys as i really havnt got the funds to investigate at mercedes, any help would be more than welcome. thanks

 

[Tan]

I have no clue mechanically, but the symptoms sounds similar to when the Mass Airflow Sensor went in my SL, which was a relatively painless repair.

 

[Bobby Dazzler]

+ 1 for MAF sensor is the first thing to eliminate - expect around £50-60 from your local main dealer parts counter and 10 minutes to fit. Money well spent.

 

[gtvlusso]

Yeah - MAF is the usual suspect - cheap and simple to replace, but get it on a STAR analysis to find everything.

I would be inclined to change the air filter at least too.

Yes, it is in limp mode, no turbo effectively. When you restart the engine it resets limp mode, but will go back into it.

Taking a while to crank is unusual, but could be related. STAR will reveal all.

 

[Ted]

Sounds like an air leak in one of the fuel pipes to me.

 

[Rory]

Sounds like an air leak in one of the fuel pipes to me.

Usually that causes cold start problems.

 

[rooby_roo]

update on this guys, i put a new maf sensor on and so far its been behaving itself, though i havnt been on a long journey in it as of yet, but the power is back and its kicking down etc when driving, :bannana: thanks for all your answers, much appreciated.