weird misfire

[flango]

OK here we go again been using the CLK as my daily since I've bent the milk float.

Get in it this morning abs and esp lights don't go out also car is misfiring it's nuts off. Have to jump in JSWMBO beetle to go see a client embarrassing or what

Get home this afternoon scan it and no fault codes even though abs light still on. Diagnostics reports multiple misfire cylinders 1234 (no **** sherlock)

MAF coil packs plugs leads battery all changed less than 3 months ago. To me looks like a classic MAF problem swap MAF and still the same.

I'm now thinking ECU

Do the panel have any thoughts ?

 

[joesoap]

I would be looking at vacuum leak look for hoses popped off, had mates TT with misfire and it was dipstick not fully home!!

 

[John Jones Jr]

I wouldn't be looking at a faulty ECU at this stage. Did you unplug the MAF?

It's possible too that you have two faults, one the misfire and two the ABS/ESP warning lights. The one thing that I'm aware of that connects the engine and the ESP is the throttle body but T/B's don't seem to be that common of an issue. Any fuses blown? Check the K40 reply fuses too.

At a bad guess I'd say MAF and brake light switch. But that's a bad guess...

It might be worth making sure the battery is fully charged and if so, disconnect it for 20-30 mins and then start her up.

 

[grober]

Bad alternator - engine/battery earths??

 

[renault12ts]

As above...bad earths.

 

[flango]

I would be looking at vacuum leak look for hoses popped off, had mates TT with misfire and it was dipstick not fully home!!

All hoses godd checked and double checked

 

[flango]

I wouldn't be looking at a faulty ECU at this stage. Did you unplug the MAF?

It's possible too that you have two faults, one the misfire and two the ABS/ESP warning lights. The one thing that I'm aware of that connects the engine and the ESP is the throttle body but T/B's don't seem to be that common of an issue. Any fuses blown? Check the K40 reply fuses too.

At a bad guess I'd say MAF and brake light switch. But that's a bad guess...

It might be worth making sure the battery is fully charged and if so, disconnect it for 20-30 mins and then start her up.

You are definitely on the same wavelength as me as I originally thought throttle body but all looks fine and as you say not normally an issue on these cars but I've not ruled it out yet.

Fuses and K40 good and did the battery disconnect trick.

Left it running idling on the drive for an hour tonight and things have got a little better now if i drive it on the road if I am very very very smooth and slow with the accelerator car is perfect minute I plant my foot it misses it's nuts off. I'm now thinking

Lambda sensor
Throttle body
ECU

At least it's driveable so I can take it to someone who can go more in depth than me to sort as I'm getting peed off and ready to bin it. Unfortunately there is no one like that around here so time to work out plan B

Any thoughts anyone on

A) what's causing the problem
B) where to take it

 

[martyz]

A fuel pressure drop would certainly be evident on hard acceleration,could be as simple
as a dirty filter,leaking hose or line or maybe the fuel pressure regulator.Can you get your
hands on a fuel pressure gauge? and another + for earth on electrical side.

 

[flango]

A fuel pressure drop would certainly be evident on hard acceleration,could be as simple
as a dirty filter,leaking hose or line or maybe the fuel pressure regulator.Can you get your
hands on a fuel pressure gauge? and another + for earth on electrical side.

Good point not checked fuel pressure this time will do that tomorrow thanks

 

[WG M-B]

The throttle body does play a part in the ESP (obviously we all know that ).
So I would be looking along these lines. With regards to voltage causing the abs/ ESP warning, these are safety critical and almost always the last to throw warnings related to voltage.

 

[flango]

The throttle body does play a part in the ESP (obviously we all know that ).
So I would be looking along these lines. With regards to voltage causing the abs/ ESP warning, these are safety critical and almost always the last to throw warnings related to voltage.

Yep agree with you, although abs light on, abs appears to be working fine when putting it to the test on the road. Hard to tell with ESP but tried to get the car out of shape and cant so suspect both systems good although lights illuminated.

It's old school diagnostics so difficult where to go next without just keep swapping out parts

 

[DieselPete]

Jswmbo - pls tell me what this means?

 

[flango]

Jswmbo - pls tell me what this means?

Junior She Who Must Be Obeyed = Daughter

 

[merc85]

Is the timing chain / sprockets ok? Just a thought

 

[flango]

Is the timing chain / sprockets ok? Just a thought

Yep perfect. I still think it's electrical or fuel delivery related

 

[horgantrevor]

What engine have you

You really need to put on star
Voltage of car when not running
Voltage when running
If your throttle body was faulty take off and clean but then you really need a star to reset its values
Vacuum leak would only make it run rough when cold
Did you drive car on low fuel if so fuel pump might be going so loosing pressure

Star test would show so much try find local Mercedes guy with one

 

[flango]

What engine have you

You really need to put on star
Voltage of car when not running
Voltage when running
If your throttle body was faulty take off and clean but then you really need a star to reset its values
Vacuum leak would only make it run rough when cold
Did you drive car on low fuel if so fuel pump might be going so loosing pressure

Star test would show so much try find local Mercedes guy with one

Totally agree I can get a Star no problem and I know how to do the basics with it but I'm no expert, in fact no one around here is including the dealers, thats my problem!

Seriously thinking about taking it to one of the reputable Indies on here and leaving it with them to bottom out as I think its now past my level of diagnostic and electrical capability

Thanks for the input though very much appreciated

 

[flango]

Just been out having another look and when the ignition is on the throttle body is buzzing like mad is this normal? I've never noticed it before.

Yours confused

 

[DSM10000]

Just been out having another look and when the ignition is on the throttle body is buzzing like mad is this normal? I've never noticed it before.

Yours confused

Ian

That does not sound right! Does the buzzing stop / alter if you depress the throttle ?

If the actuator motor is buzzing then it suggests it is sticking , perhaps some electrical contact cleaner sprayed into it might help?

 

[flango]

Ian

That does not sound right! Does the buzzing stop / alter if you depress the throttle ?

If the actuator motor is buzzing then it suggests it is sticking , perhaps some electrical contact cleaner sprayed into it might help?

Thanks for that not sure if it stops when throttle pressed will check and report back will also give it a spray with cleaner

Cheers