E240 missfire

[Rock*]

Help!!!!!!

I own a E240 1999. I don't use the car much and on the odd occaction when I started the car from cold it would idle fine but missfire when driving/pulling off. I would normally just turn it of and restart it and all would be fine.

I've been out of the country for a month and on my return the battery was flat. Jump started it and then replaced the battery. Now it is doing the above constantly. Starts and idles fine! but try to rev it or drive it just misfires. feels like asthough theres not enough fuel and/or not fireing on all cylinders?

As I said I dont use the car much could this be down to the battery running down/flat.

Whats the cure, as i cant even drive it to a garrage????

Cheers

 

[jberks]

it sounds a lot like the old Air mass sensor again - extremely common fault - but you can't be certain without a diagnostic from the dealer.

 

[ALAN@ECUCLINIC]

think i might have posted this before ! if it missfires on 2 cyls then it may be the ecu. vdo and pms ecu`s suffer with this at an alarming rate and we ,as a company have been repairing them for a number of years
please have a look at the website or call 020 8761 7482

 

[Rock*]

With the battery being flat i have read that the ecu may need reseting?
can anyone confirm that to do this you,

1. put key to stage two.
2. press throttle slowly all the way down.
3. then hole for 5 secs. and slowly back up?

this may have to be done a few times?

And does this modle have OVR. if so where is it and what does it look like????

 

[television]

There is no way that you can re set the ECU, it is a pre programed component.
Re the OVR this normally effects Idle (high idle) and you would have ESP lights on in dash.
I am not sure that it will be the MAF, if faulty, the dash would show the mal function.
Coil packs do go down on this model, as do the ECU's , could be fuel problem.

Malcolm

 

[Rock*]

Well I disconnected the battery over night and tried it the next day. started up a little lumpy but setteled down.

Now if the revs are taken up slowly it fine. Can even drive it but if ity floored a big hickup and dies. its done 65K with full MB history although sevice light has been on for a few while. I'm assuming the plugs have never been changed.

Would the service light have any thing to do with this?????

I'm going to try the plugs next. I know there is a problem with the plug leads on this model. Are they the leads to the coil packs, or from the coils to the plugs?????

Cheers

 

[jberks]

I've had trouble with the leads from the coil packs to the plugs. Went through 2 sets. However, this car is twin spark and I wouldn't suspect the plugs given the symptoms you describe. They manifest themselves as a slight misfire at idle and almost undetectable when running as even with one plug down entirely, the other will compensate to 90%. True, they are due to be changed but they can go a long while yet.

If I had to guess (which is what we are doing) I'd still say its the MAS. They symptoms fit pretty well. If its unable to detect the correct air flow, then idle will be a bit dodgy but fast running will be all over the place, especially if its detecting on and off. The ECU should detect the failure and put you in safe mode, but it doesn't have to. If readings remain within parameters, even if they are blatantly wrong, the ECU could be tricked into doing the wrong thing - as in your case.

I also had a problem with hesitant acceleration. It would pick up but only by 50% of normal, then a few secs later, you'd get the rest. That was the o2 sensor.

I was asked to look at a relatives escort (not sure why me but hey). It would idle but died when you pressed the throttle. Anyway, I found the fault. It was that the air inlet hose was leaking causing the info from the MAS to be innacurate. Reattached it properly and it was fine again. Sound familiar?

Another possibility is the cat. The innards can break free, and when the flow is high enough, get picked up and pushed into the exit pipe, effectively blocking it. I'm not sure that this affects the 240 though. I still think its the MAS.

 

[jonnyb1]

Hi,recently fitted a replacement(love that word... saves saying second hand)mass meter because of a problem very similar..result.fantastico
Cheers.col

 

[Rock*]

Solved

It was the air mass meter.

Got it Euro car parts for £180+vat.

Drives like a new car

thanks for your posts boys.

Robin