E240 Missfire Again

[thejap]

E240 2.6 2000.
Thought I had cured the missfire I had by changing leads, plugs and MAF. Over the weekend went for a good run in the car and the missfire is back.
The car was ok on local runs but the moment it gets on the open road and give it a bit of stick the missfire returns. I'm getting a bit fed up with the whole issue. I've just read another thread stating the the cat may have broken up, and I do have a rattle from inside the back box when stationary in drive or reverse. Is this the problem?? In the past when the engine light on the dash comes on after giving the car some stick and then driving quietly for a few days the light goes out. Its off for a diagnostic in the morning any ideas before I go.
Cheers

 

[television]

The cat will not make it misfire, broken or not, the fault seems more like a coil pack breaking down under load.

Malcolm

 

[thejap]

Went for a diagnostic today and no faults showing(not MB stealership). It was an ex MB mechanic and he suggest a new coil pack. I managed to find out it was cyl 5 missing before I got there by removing the coil lead and no change to the engine missfire. As I say when I arrived at the garage the missfire had gone. Another idea he came up with was a faulty ECU as he came across a similar problem a few years ago. When this missfire problem started about a month ago I did go to the stealership and again when I arrived no missfire but the diagnostic did show there had been a missfire on cyls 3 and 6 recently. That was when I changed the leads and plugs and MAF. I have ordered a coil pack for cyl 5 and see how I get on,

 

[justin1820]

been here more than once, could be control unit fault or maybe moisture inn the fuel rail

 

[television]

http://tunemycar.com/mercedes_common_ecu_failures.html

This firm can fix the ECU for £120.

Malcolm

 

[piestore]

112 missfire

Hi

I hate these problems there are many many causes and each one is very time consuming to eliminate starting with the most common first:-

Air mass meter (fault code indicates self adaptation at limit)
HT leads damaged/faulty
contaminated fuel
KAT blocked causing excesive back pressure
water/air in fuel rail
throtle bode O ring leaking
spark plugs beyond service date
Injectoror seals leaking
faulty injectors
spark output from ecu fail
wiring loom fail

112 missfire can be a real pig

 

[ALAN@ECUCLINIC]

http://tunemycar.com/mercedes_common_ecu_failures.html

This firm can fix the ECU for £120.

Malcolm

YES THEY CAN, BUT THE PRICE IS A WHOPPING £495 PLUS VAT
THE JAP, CALL ME AGAIN....YOU KNOW IT MAKES SENSE!!!(oops caps lock off)
£395 plus vat!!

 

[television]

this site gives the reason for the problem.

http://www.carelect.demon.co.uk/merc.html


Malcolm

 

[ALAN@ECUCLINIC]

now this firm is very good ,know tony quite well

 

[thejap]

Just found this site for repairs to ECU's. Has anyone had the misfortune of having to use this firm or any other for an ECU rebuild.
http://www.the-ecu-doctor.co.uk/

 

[ALAN@ECUCLINIC]

yep i know rob as well, but he cant do pms type merc ecu`s al;so had the odd bad report he used to send me qyuite a few ecu`s

 

[thejap]

The egine light cleared this morning and a quiet run around town no problems. Took car for a run tonight and within 2miles missfire back and engine light on. Got car home and pulled bonnet missfire on 5 and 6. Looking more like ECU. Where is the ECU and how do I remove it for repair? I've looked under the black cover passenger side of engine bay, found ESP/BAS box not sure what the others are.

 

[television]

The egine light cleared this morning and a quiet run around town no problems. Took car for a run tonight and within 2miles missfire back and engine light on. Got car home and pulled bonnet missfire on 5 and 6. Looking more like ECU. Where is the ECU and how do I remove it for repair? I've looked under the black cover passenger side of engine bay, found ESP/BAS box not sure what the others are.

All that can be wrong with your ECU is that the output transistors have lost their thermal contact with the heat sink, this causes the collector current to run away to the point of switch off, you do not have any faulty components in it, and it is a very simple mod,or repair. I think that this unit is bolted directly to the bulk head, but could be wrong, I can look tomorrow for you.

malcolm

 

[Blobcat]

All that can be wrong with your ECU is that the output transistors have lost their thermal contact with the heat sink, this causes the collector current to run away to the point of switch off, you do not have any faulty components in it, and it is a very simple mod,or repair. I think that this unit is bolted directly to the bulk head, but could be wrong, I can look tomorrow for you.

malcolm

Heat sink compound, works realy well, just hard to clean off your fingers

 

[maybach]

I too have been here before many times. Before going down the road of an ECU try a tin of FORTE fuel treatment. My guess is that you have water in the fuel rail, this is because you are only getting the misfire after giving it some throttle and that CYL 5 -6 are the closest to the fuel inlet. I recommend FORTE as it was shown to me how this product allows the water to mix with the fuel so it is burnt off.

Just a suggestion, but £12.00 for a tin of FORTE is worth trying before we get in to the expensive stuff

 

[thejap]

Problem solved

Firstly thanks to all for your replies, this forum really is a good way to get to the bottom of problems.
I havn't replied until now as I wasn't going to chance my luck.
The problem after all was water in the fuel. Used the Forte fuel treatment and this helped quite a bit, but still the occasional misfire, so drained down the fuel tank and replaced the fuel filter and all is fine once again.
I was starting to lose faith in my Merc but that is now restored.
Next job discs, pads and drop links.
Once again thanks for you're help.

 

[severn]

Another fault with the 112 v6 engine is that the housing that holds the rear crank oil seal also has drilling's for want of a better term that allow crank case breathing. It has been known that these can become blocked solid with emuslifled oil and prevent proper crankcase breathing. This can lead to misfires on the rea most cylinders, but is generally accompanied by higher oil consumption than normal. The gearbox must be removed along with the drive plate to be able to remove the rear main oil seal housing. I have come across this problem 3 to 4 times. The ECU are normally quite reliable on this engine.

 

[golfcarmad]

used ecu doctor last week,cheapest qte by far,unfortunately fault not ECU-£30 down,but thats ok.Just checked wiring loom-OH my GOD-its crazy paving from here to eternity-think ive found the problem!!! anyone have a loom for a 94 C280???

 

[techmani]

This worked for me

The egine light cleared this morning and a quiet run around town no problems. Took car for a run tonight and within 2miles missfire back and engine light on. Got car home and pulled bonnet missfire on 5 and 6. Looking more like ECU. Where is the ECU and how do I remove it for repair? I've looked under the black cover passenger side of engine bay, found ESP/BAS box not sure what the others are.

My c200 was misfiring like and old donkey and a good local mechanic with service history under his belt cured it by doing the following:
Used the right spark plugs from MBZ, replaced ignition cable, cable plugs and cable sleeve and suppressor plug. Tidy sum of parts £121.72 and car runs like new now. Try the cheap bits first. MBZ has said it was ECU and bla bla bla to make a huge dent in my bank balance

 

[golfcarmad]

i used ecu doctor a few weeks ago for my failing C280.std fault in line 6 cylinder,1+6 dont fire.everything points to ECU-for 30 quid i was informed nothing wrong.opened up loom and its the biggest mess you have ever seen,every single wire (30+) is cracked every 2-4 cms.My problem now is do i buy a new loom (650 quid) with no guarantee it will get car back to 6 cylinders.
ps car running fine on 4 cylinders-poor accelaration and crap MPG but I do run it on LPG so for now-it works.