E220 CDi Limp Mode

[clanca1234]

My 2005 E220CDi started running in limp mode last week (loss of power, would not run over about 3000 revs). It was fine on starting, but limp mode was cutting in when passing about 60mph. There were no warning lights, etc.

My Mercedes garage diagnosed a faulty Air Mass Flow Meter, which they've replaced at a cost of £260. However, next day, the same problem has reoccurred - again, as soon as pass 60 in 5th/6th, limp mode cuts in. Again, stopping the car, turning off ignition and starting again resolves the problem, until the next time the car passes 60 or so. This time, however, the engine management warning light is on.

Does anybody have any ideas what the problem might be? I'm hoping it isn't cat related, as that would be very expensive. Whilst I'd like the original garage to sort it out (it would be cheaper), I'm wondering if it is worth while taking it elsewhere to see if they have better diagnostics.

 

[Hertfordshire Merx]

Almost certain you will have a split in an intercooler boost hose somewhere. Normally they split on the NS top hose close to the cable tie securing wiring from the boost sensor where it bends 90 degrees and goes into the EGR valve, or at the bottom, same side as it goes into the intercooler. Have had splits in other pipes causing the same problems. Black smoke usually accompanies this fault.

Hope this helps.

 

[clanca1234]

Thanks, Hertfordshire Merx. I'll see if I can spot one. I haven't noticed any black smoke - that doesn't mean that there isn't any, though!

It's a shame I'm not closer to you, as I would bring it round for you to have a look at. Unfortunately North Yorkshire to Hertfordshire is a bit of a drive (especially in limp mode)....

Thanks again for your help.

 

[Hertfordshire Merx]

Easiest to spot it if you have someone sitting in the car and rev it up foot to the floor and off again immediately. You may hear a rush of air which should give you an indication of where its coming from...