A140 faults after changing of battery

[Pearl3942]

I have a A140 (1999) which I had to change the battery in due to going to the car each time after not using it for a couple of days and finding it dead. When I had changed I went out for a short run and it was fine, now when I drive it it judders and looses power, 20 mph max. The battery has been tested and the sparks and coil changed. The dignostic computer has bought up lamba sensor but from reading postings it does not seem the same symptoms. Can anybody help?

 

[mattkh]

... and coil changed. The dignostic computer has bought up lamba sensor but from reading postings it does not seem the same symptoms. Can anybody help?

Hi
First, why was the coil changed.
Second, what is the mileage.

 

[Pearl3942]

Hi thanks for getting back. We had a problem before with another car which had the same sort of problem which was the ht leads (apparently a class do not have these but coils). It was just to see if it was that and the old one has been put back as this has not rectified the problem. Secondly it has only done 60K. Everything was running fine until we changed the battery. When stationary it seems to surge in revs. The mechanic is trying different things and all the time costing money, hence trying to sort it myself. Cheers

 

[mattkh]

Hi
Right, you noticed that it is surging when stationary. I take it, it is manual.
Try cleaning the throttle body and the MAF sensor.

 

[BlackC55]

In the A-Class the MAF is inside the engine control unit.

Try leaving the ignition on for 30 secs.

Lambda sensors faulty can cause strange engine behaviour.

 

[Pearl3942]

Cheers guys, will talk to my mechanic and tell them what you have suggested. May also give our mechanic your number Black C55 if that ok, you being a mechanic specialist may be a help to him.

 

[Pearl3942]

Just been back to my car and tried the 30 seconds on. Drove it for 50 yards juddering really bad. Stopped done the 30 seconds again and then drove for about 5 miles, perfect. Came back to garage, turned it off for 5 minutes, drove again and it was juddering. Does this seem familiar to anybody. Cheers

 

[Cole@MBS]

Airmass sensor by the sound of it! could be as simple as the throttle flap needs a good wash out, seen that before havent we Olly!!!!

 

[Pearl3942]

The spark plugs changed, the coil changed, the trottle cleaned, the lambda sensor changed. After the lambda sensor was changed the mechanic drove it for a bit and it was fine for a while then started juddering again. It seems that when it warms up it starts. Everybody wants to say it is the ECU, does anybody think this is it? Cheers

 

[Cole@MBS]

It do sound like an airmass sensor, need to see what the live data shows up for the airmass!!

 

[Pearl3942]

Cheers Sam unit, sorry not a mechanic myself, just trying to find out to save the mechanic making an even bigger bill! The airmass is that in the ECU?? If so should I send it away for testing, can you recommend somebody, live in Bracknell. Cheers

 

[Cole@MBS]

It can be sent away for repair, you need to know that the airmass is at fault first, your not a million miles away from us, could pay you to pop in and have a looky on star!!

 

[Pearl3942]

Sorry Star?? please explain. The car is not driveable so do you mean remove the ecu and bring it to Southampton? Appreciate your help.

 

[Cole@MBS]

No, would have to have the car complete,

Star is the diagnostic machine as used by merc!

 

[Pearl3942]

Sorry the car would have to leapfrog all the way to Southampton. what a sod, thanks anyway

 

[Cole@MBS]

If you get stuck then you know where we are!!