W124 - ECU or Coil?

[maxicab]

Hi Tim
Yes, I thought you meant ECU! MAF is the airflow meter in air intake. Well you seem well able for the challenge. If its low power (but still able to run at 75 mph) without a misfire, I would have thought a 'mechanical' rather than an 'electrical' problem is more likely, but as you say, common logic doesn't seem to prevail anymore when diagnosing problems in cars. Most 124s I've seen DON'T have a lumpy tickover, even at 150K, so maybe this is a clue too. Can you do a compression test on each cylinder? An OVPR is about £50 I think, but not probably worth changing without more evidence, unless you can borrow one from another car to try. Check the 1 or 2 fuses on top of it are OK though.
There's quite a lot of info on this forum (and on the web generally) if you key in the right words to search for.

 

[maxicab]

Misfire hunt - Follow up information

"Well it's so far so good. The exasperating thing is that I don't know what has fixed it. The likely suspects are the fuel filter change, the missing ECU bolt to the firewall, or the general poke around with the ECU plug connectors"

Well it's now September and I've had no misfires for 3 months. I cautiously claim a cure. I did change the plugs to the non-resistive spark plugs (Beru brand from GSF, as they don't stock the non-resistive Bosch - and in fact they repeatedly insisted that the Bosch resistive plugs were the correct ones when I know for sure they're not - see earlier). Maybe this has helped all the other cures; I'm not sure, but it does seem to run a little better on the Beru plugs than the resistive Bosch ones.

If the intermittent misfire problem returns I'll let you all now - but will start a new post!

Thanks to all who helped me out. David

 

[rayhennig]

Cheap plugs rule!!

Do not underestimate the significance of the right plugs.

Also, do not overestimate the knowledge of your dealer.

I spent years on resistive €100 a set Mercedes (Bosch) plugs and things were never right. All this on the "advice" of my local Mercedes dealer. Now I'm on €18 a set Bosch non-resistives and the car idles, starts, etc as it should.

Also, yesterday, I travelled the 100 Km round trip to get a new battery - Mercedes princes here are very good. I was shown 2 and he said the larger was 100 Amp instead of 74 and only an extra €9. "Will it fit"?, I ask. Expert assures us that it will, despite the fact it's a petrol not diesel.

50 Km later, I try to install. The space is there but the battery holder is too short. Anyway, the holder has now been modified (nack-saw and hammer) and the battery's in.

I think your new plugs might have been the cure.

Bonne chance.

RayH

 

[maxicab]

Non-Resistive Plugs

Thanks Ray,
Yes I agree, the cheaper the better! I think the incorrect spark plugs probably have been quite a significant issue here, but I've had so many false successes that I hesitate to preach. But the American chap Arthur (see link contained in post 51 of this current thread) seemed to be absolutely certain that Resistive plugs should not be used in Mercedes engines that specify non-resistive plugs. I'm just surprised that I could find so little about this issue on UK forums.
I agree that the main dealers often aren't well informed, but in this case it was GSF and their reference books that were wrong. And the Not so local Indy had installed the correct plugs last time they were changed 2 years ago; I only put the wrong plugs in during the misfire hunt when I changed all the coils. So the wrong plugs definitely weren't the original cause of the misfire problem. They may well have perpetuated it though.
Sorry to hear about your battery nightmare.

David

 

[E320C]

Plugs

Hi guys, Reading your discussion on resistor and non resisitor plugs?

I run Bosch FR8DC+ on my E320 Coupe and my dad's E320 Coupe?

Not to tempt fate and touch wood they run spot on at 144k and 32k respectively. We previously also tried Champion RC10YCC and they were fine too.

The original Merc plugs as fitted by MB was made by Bosch, (with MB logo) part number: F8DC4. FR8DC+ is the new version with resistor and yttrium electrode.

I thought the idea of resistor plugs was to eliminate any potential problems associated with interference on electrical goblins like ABS, Radio etc?

Regards

E320C

 

[maxicab]

Its a long story

Hi, thanks for the interest. I can't explain why your cars have had no problems and yet we have both had problems with resistive plugs in similar cars. I was running exactly the same plugs as you which I unwittingly believed were the direct replacement for the originals.
I think your suggestion is right for the reason that built-in resistances in plugs have become the norm; the problem is that there is already an inbuilt resistance in the plug to coil connectors in these engines, so the total resistance may be excessive in some situations but not others I guess.
There is a VERY long (sticky) thread on it here -

http://www.mercedesshop.com/shopforum/showthread.php?t=197392

- with some very interesting discussions, some not easy to follow, others very easy. It's obviously a contentious topic. Near the end of the thread is a chap who tried absolutely everything over a couple of years to make his car run right, then he changed the plug type to the non-resistives and bingo, everything was cured! Hopefully my success will be similar!
David

 

[E320C]

Plugs

Hi David, the link regarding resistor and non-resistor makes interesting reading. According to GSF carparts website they still stock F8DC4. I might give them a go next time. If memory serves me right they were very smooth plugs too. Its been such a long time since I have used non-resistor plugs on mine I can't actually remember what type of plug was better?I would be very interested to know what plugs other 104 engine owners use?* RegardsFranz

 

[kth286]

I always go with what Mercedes specify in their latest parts book, and that is NON resistor plugs.

It shows Bosch, Beru, and Champion alternatives.

After all, it was Mercedes that designed the car - not GSF or Eurocarparts !!!!!!!!

 

[maxicab]

I agree, good advice David, and in my recent experience, I think it does matter!
My local Mercedes Main Dealer recommends only 3 plugs for W124 E320 104.992 distributorless engines:
Bosch F8DC4 (£2.10 each from them), Beru 14F-8 DU4 and Champion C11YCC. Note the lack of an "R" in any of these codes!
The issue I have is more with aftermarket suppliers (yes, GSF and ECP have both done this to me, but so have the local motor spares shops), who will substitute an "equivalent" or a "replacement" plug because "those old ones are no longer available". Or they may even try and sell you some "much more modern and greatly improved new design" plug, that will give you a better spark or whatever. And one logically thinks "why drive 20 miles to just buy some ordinary spark plugs from a main dealer".
The correct Beru plugs can be bought from GSF for peanuts and they seem to be working just fine so far.
I've been trying to contact you for ages David about your fault code reader, but have had no luck so far. Do you mind sending me or posting me the design or a link to it and the instructions for use?

Thanks, David

 

[maxicab]

Ahhhhgggg! - W124 E320 intermittent misfire is back!

OMG.....Just when I'd finally decided that it was safe to claim victory, the intermittent misfire has returned to haunt me. It appeared to splutter only very slightly, very briefly, a couple of times early in the week, but then ran roughly on 4 cylinders for a good 5 minutes on Thursday at the end of a 12 mile trip including a longish wait at tickover at a level crossing (and only abruptly stopped misbehaving when I arrived home, decided to wiggle and fiddle with things a bit with misfiring continuously going; tried some of the previous suspects with no effect, then took off the fuel cap (a second time) and then hey presto, suddenly the misfire disappeared.
I went downtown to get some fuel as I thought that maybe there had been a vapour lock of some sort as the fuel was very low and I indeed managed to then fit in 57.5 Litres. It ran perfectly on Friday, but today (Sat) it misfired again for a few seconds when pulling away from a junction a mile or so from home after cold starting, when the car would have been barely luke warm.
I have a hunch it might be something to do with having applied the brakes somewhat heavily just prior to it happening on both occasions. Is it possible that the servo assist could rob the inlet manifold of negative pressure, cause a temporary change in manifold conditions that makes the ECU go into a Limited Operating System (LOS) (Limp Home Mode)? Could there be a vacuum leak which is somehowwonly manifest at times (I can't reproduce the effect now on testing)?
Is anyone out there able to help me on code readers for this model, as it strikes me that if I had a suitable fault code reader in the boot, next time it happens I could whip out the code reader and check for fault codes.
I'm going to open a new thread on this as I think this one is long enough. I'll summarise the events to date

David

 

[diy_dan]

This is trivial when compare to your fault but I just bought an e320 coupe, The chappy said he had the head gasket done and gearbox oil change because he was planning on putting twin compressor on it. anyway I took it for a test drive and it ran ok. I thought the engine was a bit dirty so got some degreaser from the pound shop and gave it a wash, A few days later the car was running real bad, oh by the way he had someone taped up the loom with electrical tape. anyway I thought I must have blown the ecu after reading threads like this, The funny thing was the car would start ok then as it warmed up it started to missfire, I had a quick look for prices on coils, the missus was saying I should have kept the other car(300ce metalic black) This one is the same colour and interiour but with cruise and ac which doesnt works.
I got some plugs to change since I figured it was running on 4 cylinders. when I took number 5 plug coil out the tip looked a bit damp. When I removed the plug it was wet with water. the same with number 6 plug. What happen was when I washed the engine water got into the plug port and when the engine got warm the water turn to steam and start shorting the plug out, So if your car start misfiring before spending hundreds, check the plug port for water, Ok it might not have been the reason your car was missing but since mine was running ok before, I knew it had to be something trivial and in this case it was
Dan

 

[power-steering]

It's a common problem on the mercs unfortunately. We repair on average 3 a week with the missfire issue. It's the coil packs which blow out the ecu. We advise you change the coil packs BEFORE putting your replacement/remanufactured ecu back on the vehicle (even if they were once changed before) because if you don't, you risk blowing it again!

Common faulted part numbers are as follows:
0261 200 612
0261 200 614

There are others but like I say we do 2-3 of those part numbered ecu's every week.

If you haven't solved your problem, give us a ring on 0208 853 3343 and we'll do yours for you with full 12 months warranty.. £340+VAT

Good luck,
Jay

 

[television]

It's a common problem on the mercs unfortunately. We repair on average 3 a week with the missfire issue. It's the coil packs which blow out the ecu. We advise you change the coil packs BEFORE putting your replacement/remanufactured ecu back on the vehicle (even if they were once changed before) because if you don't, you risk blowing it again!

Common faulted part numbers are as follows:
0261 200 612
0261 200 614

There are others but like I say we do 2-3 of those part numbered ecu's every week.

If you haven't solved your problem, give us a ring on 0208 853 3343 and we'll do yours for you with full 12 months warranty.. £340+VAT

Good luck,
Jay

Can you recondition a 140 dual pump

 

[power-steering]

I believe so. Best person to ask on that one is Danny another of our manager's there.. give him a ring between 9-5 tomorrow on 0208 853 3343.

I've been there 2 years but he's been there since the beginning so he's best person in regards to that.

 

[meanie]

First time that I've seen this thread but I'll stick my two pennurth in anyway.

On the subject of ECU's on cars with the infra red locking system,it is possible to fit secondhand units-I too was under the impression that they were coded to the car,but was put straight on this.I had an E36 earlier this year that ended up with a secondhand ECU & can confirm that used is ok.

Engine harnesses-the other area of weakness is in the area between the baulkhead & the inlet manifold.The harness is easily removed,and on the bench are easily rewired.If stuck you can re-use the old connector blocks,just take your time,solder all connections & use heatshrink,use the coil wiring repair kit from MB,and always rebind them with a cloth based tape ( I get mine from MB,it's the cheapest that I've found).

Finally,I note not mention of a possible head gasket flutter between 2 cylinders.Not the usual place for a 104 h/gasket to fail,but it does happen.