W203 coupe hunting idle and no accelerator

[Mikesx13]

So, I've been fixing up a w203 coupe that had various issues. When I drove it onto my drive 6 months ago the engine purred sweetly and the gearbox seemed nice enough. At various points over the last 6 months I've started the car, had the battery on and off, recharged the battery after it drained completely etc etc.

I've now finally finished the car (or so I thought!) So started it up to a nice purring engine, left it running while I did something else then switched it off, came back five minutes later, started it only to find a hunting idle, stench of fumes/petrol and a non functional accelerator pedal.

I've tried ECU reset, dyno mode, pedal reset. I range from having 1 to 4 errors including esp, battery/alternator.

The fault is very intermittent i.e. will start and drive fine one minute and not the next.

Everything else on the car works fine (apart from the key fob) including the rear brake lights, oh and also the external temp is reading -40 degrees (could that be a problem?)

So, are there any common fixes for this?

Thanks.

 

[Mikesx13]

No comments on this?

If I changed the pedal, MAF, throttle body and ECU could I pretty much guarentee a fix?

 

[sallison1504]

The smell of petrol would have been a result of over fuelling, as the car thinks it's in -40.

The hunting probably would have been the ECU getting strange readings back from the O2 sensors.

I'd check and clean the MAF. If you're replacing it, use only MB parts.

 

[BlackC55]

Is it a Kompressor?

Get it plugged into a Star and diagnosed properly. Stop throwing parts at it!

 

[Mikesx13]

Strange, thought I replied to this!

The car still thinks its -40 when its running fine so that rules that one out although I can see where you're coming from.

If the MAF was faulty it wouldn't result in the throttle pedal not functioning although it could result in rough idle.

I'll clean the MAF and TB as a matter of course but logic tells me it isn't either of those.

I've come from the s body world which is very much DIY - as a result you learn an awful lot which is the fun part isn't it?

Besides the nearest Mercedes dealer is about 45 minutes from here and I'd have no guarentee of starting the car to get home!

I've had a few ideas this evening.

I bought the car damaged, one of the problems was the air con pressure sensor that had been ripped out at the SAM end. Being focussed on other things I just unplugged it from the sensor and forgot about it 0 I now need to investigate whether there are any bare wires etc. under the SAM.

Another thing is that there is no outside temp sensor on the car, I wondered what that other plug was for! There were two plugs exactly the same in the area of the washer bottle I chose the one that looked like it was taking the right route and plugged it into the washer bottle - I may have plugged the outside temp plug into the washer bottle sensor!

Anyway, a few things to check I guess.

 

[Mikesx13]

By the way - I haven't thrown any parts at it yet, that's not my style - logical diagnoses and checking first parts second - I just posted that to get a response.