Whats wrong with my car - engine cuts out under load.

[wasc]

Hi everyone,

Got a Merc A Class - the Diesel one (A170).

When it's placed under a heavy load, the engine just cuts out completely, which makes overtaking very erm, interesting

As an example, today on a clear road (40mph) I put the car into 2nd gear at about 15mph, and pressed the accelerator firmly (probably about 3/4 of the way). The car goes from about 1.5k rpm up to about 3.5k (which probably took 2 seconds to do) and then promptly cuts out somewhere between 3.5k - 4k. (And can I say the A class is a right **** to steer into a side road with the power steering cut out due to the engine cutiing out. Need both hands to turn the wheeel lol.

It's not just limited to heavy acceleration. When I was driving back home from uni (i.e had the back of the car loaded up with all my things) the car cut out 11 times on the 1.5hr journey home, one of those times was on the moterway at 60mph.

As some further info, when the engine has cut out, it wont start again for a while. If i turn engine off (i.e turn key all the way to left, put car in neutral, hand brake on, and then turn ingnition on, the engine just turns over. It doesn't catch at all, even if I pump or press the accelerator. Only solution i've found is to give the car 60 - 120 seconds before trying again and it usually starts fine then.

So - any ideas? I only have one light on the dashboard when the engine cuts out - think it says ECU from memory - really should take a note next time. Merc already put a new ECU chip in which hasn't done anything to the car - same fault.

 

[wasc]

Could be one of a few things, quite likley to be your air flow meters, fuel pump or ECU problems..

I take it the car idles fine?

Thanks for the reply - car runs perfectly - no symptoms whatsoever except seemingly random cutting out under load. Not limited to a certain rpm, speed, or gear. Idles fine.

Forgot to mention, now you mentioned air flow, the car is a Turbo Diesel if that influences anything.

 

[wasc]

sounds like a lack of fuel due to debris in filter/fuel line or an air flow meter problem.

Any idea if these things are easy to check yourself, or should I take it to a garage to check? You can probably tell I know little about cars

 

[wasc]

A fuel filter IS the most likely suspect. A dirty fuel filter will not just all of a sudden cut the fuel flow off making the car not run at all. It will start by restricting the maximum volume of fuel flow - which is at full throttle. It will get steadily worse as the filter gets more clogged up.

The reason the car takes a while to start back up is that the offending clogging will become smacked so hard against the filter from the pressure, then it takes a while for the low side pressure to slacken to allow the gunk to fall off and let fuel flow again. I've had this happen several times myself (granted not on an oil burner).

It could be several other items, but the most likely is the fuel filter. It's also the cheapest to fix.

Thanks, I might phone a few garages around and get a few quotes. Not too good with cars myself so wouldn't want to try it unless if it's fairly easy.