202 C220 Petrol '95 misfire

[MB_Singh]

Hi. The car is currently running on two cylinders. Cylinders 2 & 3 are not running. No spark or fuel. It does how ever, send the test pulse on both the injectors and spark plugs and then cuts out. I have tested the leads, spark plugs, injectors, coil packs (twin coil packs under inlet manifold). These all checked out fine. Sometimes, for no apparent reason, the car runs fine for a short period and then goes back to running on two cylinders again. Has anybody got any ideas? Its got the VDO ECU in the scuttle panel in the engine bay.
Please help!

 

[LAMAR]

If I remember correctly the 202 4 cylinder only has two coils (wasted spark)
swop the coils over is a quick test to see if the misfire moves to the other cylinders.
If the engine misfires over a given time the engine ecu will shut of the fuel injector to the faulty cylinder until the car is switched off and re started.
another thing to check is the engine wiring harness over time becomes very brittle, open up the wiring ducting where the injector wires run and check for any damage.
other then that properly the ecu.

 

[MB_Singh]

Tested the coil packs and injectors. All is fine. Diagnostics shows misfires on all cylinders? There is a misfire counter on cylinders 2 & 3 that are high. No luck after reset. The thing about the wiring is that the test pulse upon initial cranking gets through fine. Wouldn't this eliminate the chance of broken wiring? Will check anyway. Thanks for your help.

 

[MB_Singh]

Right, sent the ECU off for testing. Its faulty. Where can I get another one? Its not coded to the car is it? The car is actually a 1994 model C220. Or who can do a cheap repair? Places want £500+ for repairs.

 

[jberks]

have you tried these guys?
http://www.carelect.demon.co.uk/inspect.html
Prices on the web site didn't seem as heavy as that. Never used them though.

 

[MB_Singh]

Thanks. I will ask them for a quote. The last guys I sent it to have diagnosed the ecu faulty but cant get hold of the components to repair it. :cry:
This car is really starting to pee me off! How common are these failures? Anyone else had this happen?

 

[jberks]

There is a section on their web site detailing common failures - may give you an idea if yours is a known issue.
Failing that,
www.mercman.net
or
http://www.thegarageuk.com/index.htm
for a used one.

 

[MB_Singh]

Ok got the ECU back. £380 inc delivery. Faulty ecu and coil pack. Both replaced and now fine. Now exhaust has blown its baffles!

 

[jberks]

who did you get to repair the ecu?

 

[kth286]

MB Singh

Be very wary - there is usually a reason that the coil blows in such dramatic fashion that it also blows your computer (ECU)

Around that time there was a fault in engine wiring harness feeds to the coils.

The insulation fell off INSIDE the thin outer covering whenever spark plugs were changed for example and the harness moved out of the way.

The wires inside the thin out covering will short when they touch each other and blow coil and possibly ECU, such as in your case.

You need to check your coil feeds pronto by carefully cutting away the outer insulation and inspecting the state of the insulation on the actual wires.

By now they will probably be very brittle which of course does not help.

Plese do give us all the details of the ECU repair company.

Regards

 

[MB_Singh]

Hey guys, guess what, looks like the misfire is starting to re-occur! The cables that feed the coil packs are fine from what I can see with the inner insulation still in tact and no shorts. The car intermittently misfires now and sometimes stalls but most of the time it runs fine. Crank it over again and its fine! The details of they guys who repaired it are as follows.

1stCHOICE ECU
Unit 5
Brookmarsh Ind Est
Norman Road
London
SE10 9QE
Tel :0208 853 5000

Is the wiring harness for the coils available as a repair kit from MB or will i have to wire it by cutting the loom?

 

[QUOMAN]

DETAILSOF ECU COMPANY( MR SINGHS) WWW.GREENWICHCARPARTS.BIZ OVERHAUL ECU FOR MERCS PMS AND HFM PRICE (ONLY GIVEN IF THIS SITE IS MENTIONED) £320/£420 PLUS CARRIAGE AND VAT CAN TAKE A WHILE TO REPAIR CALL 020 8853 5000 AND DONT FORGET TO MENTION THIS SITE
MR SINGH PLEASE CONTACT ME, ALAN AND LET US LOOK AT THE ECU AGAIN UNDERWARRANTY, OF COURSE

 

[MB_Singh]

Hey guys. Thanks. I will pop the ecu back into the post to you. Chears.

Gurdip