E280 W124 Spark probs

[barrymac]

Hi I'm a newbie here having recently bought an E280 W124 Estate and having a bit of a prob with the car only running on 4 cyls. Only started happening after I changed spark plugs during servicing - plugs are correct and all good - I can only think I've disturbed something during changing plugs. Have tried new coil packs and leads all seem ok. AFter speaking to a local garage they checked for faults and adv there was a fault code suggesting a faulty ignition module? Tried a couple of searches on the net and on here - is there something really simple i'm missing?

Cheers!

 

[rpe2]

You may have damaged the wiring loom. These can be very fragile if an original.

Richard

 

[barrymac]

You may have damaged the wiring loom. These can be very fragile if an original.

Richard

Thats what I thought but the garage have said the wiring checks out ok. More woried about the fault code - Fault with ignition control module
I remember having an audi and when the coil pack went it damaged the ecu! That was rather expensive - hoping for nothing that costly!

 

[andy_k]

sounds like a wiring loom issue to me as well - seems we have reached the point where a lot of them are failing at around the same time

Have a look around the loom and looked for cracked insulation - if you find any, then you can guarantee the rest will be the same

Andy

 

[barrymac]

Loom would make sense to me - especially now that we have found out the car runs even worse when the cover is bolted down across the top of the coils! anyone an idea what kind of money is in a loom?

 

[andy_k]

funny you should ask that

http://www.mbclub.co.uk/forums/showthread.php?t=67830

I've just got off the phone (after reading your posts) from the dealers

 

[BlackC55]

About £460 I think.

 

[barrymac]

pick me up from the floor

 

[barrymac]

Well as it turns out I've just spoken to a decent autospark and he reckons that as all the wiring is LT he should be able to manufacture a loom or replace any broken / damaged parts - fingers crossed as it sounds way more cost effective!

 

[andy_k]

Well as it turns out I've just spoken to a decent autospark and he reckons that as all the wiring is LT he should be able to manufacture a loom or replace any broken / damaged parts - fingers crossed as it sounds way more cost effective!

you are playing a very risky game.....

if one part of the loom is knackered, then you can bet the rest of it isn't far behind (they were designed to bio-degrade). Manufacturing the whole loom will probably cost about the same as buying from Mercedes and you will not have the moulded parts which are factory sealed (the looms rot inside those as well). If he misses one wire that is faulty, you could still end up with a fried ECU.

I'd suggest changing the whole loom, whether or not you buy it from Mercedes is up to you. I think once you start you should add up the costs of an auto electrician fabricating you the whole loom (which will mean your car being off the road whilst he duplicates the loom), replacing/rewiring all the plugs and connectors (which I believe are 'single use' and are only available from Mercedes Germany) before fitting what will always be a compromise and compare it to a couple of hours DIY work fitting a loom matched to your car by it's chassis number.

HTH

Andy

 

[Vlad]

Really does sound like the classic wiring loom problem, ie change plugs, have to bend loom back from coil packs and hey presto it breaks down.....normally knocks out the coil pack and then knocks out the ECU as per the problem you had with the Audi.

 

[500E]

My E280 W124 just got the same problem.

Paid £700 last year for entire new wiring loom fitted. Year later and cylinder 2 is now misfiring. Decided to sell the car off now in its current state and buy another Benz.

All the best with your E280 - they are wonderful cars when working!

 

[kth286]

barrymac

Yes agree with others, and I have lots of experience of this going back around 7 years.

You moved the coil feed wiring loom to get access to the plugs AND because it is clear you have an old loom, which will be brittle inside the black outer loose covering, you action has cracked the insulation on the inner wires which you cannot see until you snip off the outer loose cover with a small scissors.

On start up the current jumped from one wire inside that cover to the wire next to it, in other words it has shorted.

The coil has blown (as you said you changed it) AND the ECU has also blown.

The cost of a new ECU is around £1000 !!!!!!!!!!!!!!! (last time I looked, but there are various versions depending on the options on your car.

It is one of the three output driver circuits of the ECU that has blown, hence no current to your new coil.

So, essentially you are into approx £1600 worth of parts at new prices.

Did you do any research on your intended purchase ??????

You might be able to get the ECU repaired for around £400 but there is a very mixed bag of operators out there - so be careful.

 

[Dieselman]

Before condemning the ECU, test it. Each coil is fed with 12v which the ECU then shorts to Gnd to make the coil operate.

Use either an analogue voltmeter, Dwell meter or an LED across the coil feed wires as a test.

Do not run the coil fully operational with the HT leads disconnected as the back EMF is likely to blow the output drivers.

No reason why the drivers can't be replaced cheaply. I replaced one in our old car for about £5.

 

[Bill_33]

you are playing a very risky game.....

if one part of the loom is knackered, then you can bet the rest of it isn't far behind (they were designed to bio-degrade). Manufacturing the whole loom will probably cost about the same as buying from Mercedes and you will not have the moulded parts which are factory sealed (the looms rot inside those as well). If he misses one wire that is faulty, you could still end up with a fried ECU.

I'd suggest changing the whole loom, whether or not you buy it from Mercedes is up to you. I think once you start you should add up the costs of an auto electrician fabricating you the whole loom (which will mean your car being off the road whilst he duplicates the loom), replacing/rewiring all the plugs and connectors (which I believe are 'single use' and are only available from Mercedes Germany) before fitting what will always be a compromise and compare it to a couple of hours DIY work fitting a loom matched to your car by it's chassis number.

HTH

Andy

I agree and no offense BUT

you are a (genuine) source of joy to us who have E280 W124s
I bought one a few weeks ago AFTER reading the loom and cylinder head gasket problems
I am just waiting for the "call"

 

[500E]

The ECU might be avaliable out of my car (95 E280) if no one buys the entire thing.

I will be parting it out in a few weeks if it doesnt sell as whole.

 

[andy_k]

I agree and no offense BUT

you are a (genuine) source of joy to us who have E280 W124s
I bought one a few weeks ago AFTER reading the loom and cylinder head gasket problems
I am just waiting for the "call"

Bill, waiting to 'get the call' could work out quite costly. Think of it as preventative maintenance and it puts it into perspective - a new loom will last the life of the car - if you keep it five years that's about £2 a week.

Waiting until it fails could easily write the car off as coil packs and ECUs are even more expensive.

I've posted another thread where we can all get 17.5% discount on the looms so hopefully that helps spread a little more joy

At the end of the day, W124s are getting old now and although in their prime they were 'bulletproof' they are made from metal and other materials which sooner or later will decay.

I think anybody buying a 15 year (at least) old luxury car has to expect a few big bills - look at what your car cost new (not what you paid for it second hand) and a £500 loom fades into insignificance.

 

[kth286]

500E

Is the OS front wing good ? In case you part it.

What colour is the car please ?

 

[barrymac]

I guess the worry I have is simply I bought the E280 as a daily smoker to take the miles and put less miles on my other car. It is a very clean W124 - no rust good interior and full service history. What I don't want to do though is change the wiring loom at a cost of £500 odd quid then find out it's the ECU thats gubbed too. Then a repair starts to look uneconomical. At the end of the day I'm pretty sure I could make back more than what I paid for it by breaking it - but it really would be a shame as it really is a nice one.

 

[Vlad]

Barrymac......if your E280 is running well and still on its original loom, then I suspect that the ECU will be fine as it normally shows up pretty quickly when its not happy....with this in mind a new loom would make good sense if you intend to keep the car.

Saying that, if the car only cost £600 who cares about the wiring harness.......run it as it is until the fateful day arises, which may be some time off yet depending on the state of your loom

To do a quick check on your loom, look at the wiring on the coolant temperature sensor at the front of the engine....the loom is exposed at this point and there are two wires poking out from the sensor....if you see any cracking on these two wires you can assume that the rest of your loom will be in a very bad way.