Puzzled everyone so far....

[curlyearly]

Hi all

I have an annoying on-going issue with my 2003 ML320 petrol. 50K miles. FSH. Cossetted.

Symptons:

Cold starting. Starts on the button (key) but when pulling off loses 50% power. If I let warm up for two minutes it runs perfectly.
Warm starting. Sometimes cuts out totally needing 1/2/3 restarts. Can be hesitant for first 50 yards.

In both cases, within 200 yards OK for rest of journey, be it long or short.

Whats been done:

Has been two three garages; firstly my local, then a specialist MB alternative garage staffed by ex MB employess and finally MB dealership.

Each outlet voices the same opinions, mostly based on a computer but also their expereince. I kid you not when I say I have had the following items changes three times ...

Plugs - they all have their own chosen "one"
Leads - see above
Coils - running out of ideas
Lamda sensor - see above
TDC sensor - see above.

There is some considerable cost to these items. I've had enough. The fault is there 50% of the time. It was there when I visited the garagtes in question. I have no problems with these garages I just want the car engine resolved.

Ideas please.

 

[markjay]

Have you been told of any fault codes found when the car was connected to STAR (or other code scanner)?

 

[moonloops]

Maf !

?

 

[markjay]

Incidentally, which 'Leads' would these be? As far as I know your car does not have HT leads (though I may be wrong).

 

[Deleted member 37751]

Sounds like injectors to me.

 

[markjay]

As far as I know injectors problems tend to manifest themselves at higher engine loads/revs rather than at idle?

Also, given that the problem appears to be temperature related, have they considered the ECU temperature sensor (or its wiring)? A faulty unit would feed incorrect data to the ECU potentially causing over-fuelling etc. But this needs to be checked with Live Data stream on STAR or similar equipment.

 

[Deleted member 37751]

If it's injectors, it'll run like a bag of spanners at idle and under load.

 

[rpe2]

Crank sensor for the cutting out whilst warm (assuming this isn't what you refer to as the TDC sensor).

This rarely shows up as a stored fault, but it can be tested by removing it and dipping the (non connector) part in a cup of hot water. If the resistance changes from cold to hot, it indicates it may be on its way. The part is circa £65, located on the top of the bellhousing.

As for the MAF suggestion above, disconnect it and see how it runs (it will fall back onto a default map)