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2007 S600 ignition failure, here we go again

7K views 16 replies 3 participants last post by  George993 
#1 ·
All, as I posted last year, my 2007, S600, 100k miles had cylinder #1 misfire error, later multiple misfires on the same bank. I changed the spark plugs on that side and the ignition cassette. No improvement. So I changed the center ignition module/voltage regulator. Problem fixed. Several weeks later cylinder 1 misfire was back. (Only #1). Any ideas? I put a bit of dielectric grease on the plugs so the cassette slides easier next time and someone told me this could be a problem and I should remove/clean the grease. But I don't really feel like taking the ignition cassette out again, plus I had identical symptoms before I started doing anything to the car. So I don't want to be replacing the same parts again. No other error except #1 misfire and the usual low engine power.

So what are the recommendations for a next step? Could the problem be related to a poor fuel mixture/injector, and say swapping injectors 1 and 2 plus new injector seals would be the next step? Is there anything else that could be going wrong? I don't suspect low compression as the car was running well many times after resetting the error.

What is so special about the cylinder 1 that the problems always seems to start there?

thanks for your help
 
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#4 ·
Hi the fuel pressure is 55-60 psi at idle and 50 under throttle which is good. I replaced the injector with a brand new Mercedes part - major pain with so many parts including throttle and wiring harness needing to come out. Still same error. So I took the plugs out and checked compression- luckily good!

Any thoughts on how to check electric signal going to injector? Has anyone tried looking at a spark using removed cassette with a plug inserted and touching engine block- just like it's done with old cars using ignition cables? Or will it damage the cassette? Thanks!
 
#6 ·
Ok, thanks, I will not do that testing. Yes, I have DAS access, will it show more than OBD2 reader? In which menu fields? I used DAS when the problem first popped up last year and from what I recall it did not show any other errors than Cylinder 1 misfire.
 
#8 ·
With DAS it allows a lot of live data to be viewed as well the abiliity to test the injectors and more, it is well worth having a good look at just what it can do for you.

Just a thought do you have a ticking sound from the motor? I'll get Dave to have a look at this thread he may be able to guide you through the testing.
 
#9 · (Edited)
Hi,

Firstly, (and I tell this to everyone), forget trying to diagnose anything on these cars with OBD, imagine trying to look at the whole of your street through a 10mm hole drilled in your front door !!
You simply don't get the whole picture....... SDS (DAS) is the only equipment to use on these cars.

As Dean rightly says, it allows you to look at live Data, and carry out specific Testing related to your problem, and much much more :wink

So lets start by going back to basics, which cylinder are you calling number 1, (forgive me but I've seen this a million times) :wink

Number one is RIGHT SIDE Front cylinder, so as you look under the Hood, it is on YOUR LEFT nearest the Radiator :wink

Also, I cannot believe you only changed half a set of plugs !! Did I read that correctly ??
I hope that they were at least decent plugs, not cheap EBay Jobbies.
Worn and El Cheapo Plugs with a large gap unduly stress these coil packs and cause failures.

You ask why it always seems to be coil pack 1, this is simply because Cylinders on bank 2 switch off during Light Throttle Cruise situations, so they don't do as much work as the Pack on bank 1.

A fault in the Voltage Transformer Module will usually wipe out an entire Bank of cylinders, as it is like 2 Transformers in one box which step Volts up and down to the Coil Pack Assemblies on each bank L & R and is a less common fault.

Injector faults and compression issues are far less likely than Coil problems, but please do tell us if you have the "Ticking Noise" that Dean questioned, it is more noticeable hot and there is an issue of several Cam Train problems that can cause this, including broken Camshaft Caps, often times on Bank 1.

Was it a s/h coil pack you fitted ?? If so chances are it has gone bad.
Forget cheapo EBay coil packs, they are Chinese knock offs, and unless you have a huge budget, forget Mercedes too...........

Check this company out :- V12icpack, Mercedes S600 ignition coil pack repair, ECU, misfires V12 engines - Home

HTH,

Cheers Dave
 
#10 ·
Thank Dean and Dave, now you guys scare me with that ticking noise :eek

- I will obviously need to study DAS and learn more about it
- I call number 1 the same as you have described
- plugs are OEM NGK, bought for both sides, I have not just got around to doing the second half yet (I can't afford the cheapo parts on this car so I only buy Mercedes or equivalent :)
- The cassette was actually rebuilt by V12icpack with new coils and new transistors

To the main point - unfortunately I have a slight ticking noise on the same side of the engine. I have heard similar noises on my other cars in the past, and often they got away once the hydraulic lifters got warmed up etc so I have not worried too much unless they went loud. I can expect valve problems on a 30-40 years old Mercedes V8 (valve problems due to clogged up oil passages and worn cams etc) with lots of mileage, but not on a modern relatively low mileage car! And car ONLY maintained by Mercedes by the book (one owner who happen to be a well known person actually making millions a year, until I bought it about a year ago)

So how to diagnose the ticking noise now? And are there any fixes short of having the head removed?

thanks!!!
 
#12 ·
Hi George,

OK, first thing I'd do is contact V12icpack and see if they can send you a loaner coil pack, or check out the one you have by return, just in case it's gone bad :wink

Check this out first.

Next up, as Dean says, try the stethoscope to see if you can track the ticking to the No.1 cylinder area by testing along the cam cover with engine running.

Is the noise louder when hot ??

Certainly if it is, it would be well worth removing the cam cover and having a good look, especially at the Camshaft Bearing cap No.2, 2nd one back from the front.

As Dean says, there is no need to even think about pulling heads off at this stage, I have successfully replaced these with "good used" a few times now :wink

Yes, I know Mercedes and other "Engine Gurus" will tell you these parts are 'line bored' and match with the Heads, but the fact is that these Engines are all machined to such "exact standards", that one can usually, (in the early stages of "tick tick tick"), get away with swapping out just the broken cap .........
I know I have :grin.

If you don't find a broken Cam Cap, then have a good look at the Cam Lobes and turn Engine to see if there is an excess clearance on a Lifter on Cylinder 1, perhaps a stuck Lifter or bad Oil Feed :wink

Let us know what you find.

HTH,

Cheers Dave
 
#13 ·
ok, both excellent advice, thanks! This makes me feel a bit more relaxed now, I'll check and will let you know - as I've started to research the ticking noise on the web I've run into the post below posted by "mercedesjunk" member, certainly not a pretty picture and hopefully it's something much easier in my case....

"From the beginning my V12 SL600 engine made a slight ticking noise when in idle. With 18000 miles and several visits to the dealership it was discovered that the noise was generated by piston slap from the left cylinder bank. The vehicle is now almost 1 year at the dealership and the special service technicians came out to the dealership at the minimum 7 times. The cylinder, pistons, ECU, coil packs. Injectors and intake manifold was changed one after another. But the engine is still misfiring on the left bank of cylinders as it did from the beginning."

Thanks!
 
#14 ·
Dave, Dean, but just for my education, how can camshaft bearing cap go bad and at which area? I would think that's something which is not moving and does not make contact with moving parts, so how does it wear off? Does it simply crack from vibration? thanks
 
#15 ·
I've been trying to find any clicking noise but luckily could not hear it, whatever was causing it (a long while back) has gone away.

In summary the problem was the Voltage Transformer for the second time (VT - the box in the middle on top of the engine). The long story from the beginning (each step no impact unless noted):
- cylinder #1 ignition failure started showing up, later multiple different cylinders started failing
- replaced the ignition cassette, spark plugs and red insulators, worked briefly but multiple different cylinders started failing
- replaced the VT with a rebuilt one (not from V12icpack): the car worked briefly but the ignition failure came back only on cylinder #1
- of course each failure was being cleared many times and it kept coming back
- checked fuel pressure, good
- replaced the fuel injector with brand new MB part
- checked compression - good/same as other cylinders
- swapped spark plugs on cylinder 1 and 2
- looked inside the cylinders with that camera on a wire gadget, same carbon buildup on cylinder 1 and 2 (if anything, there is more carbon on 2)
- listen with a stethoscope to the valve noises - same on all cylinders, nothing unusual
- so decided to start from the beginning, borrowed the cassette and VT from Clark at V12icpack
- swapped ignition cassette, no change
- swapped VT, problem solved. So my VT went bad again first time shortly after installation.

In summary if anyone gets that problem I would recommend starting with swapping the VT with a known good one, as it only takes about 5 minutes and (unlikely the fuel injector for example) is probably the easiest job on this car.

One thing which I still don't have the answer for is: why was the bad VT only affecting cylinder #1? (VT has 2 halves each serving one bank). I can understand that if voltage of VT goes below a certain level, an imperfect cylinder (e.g. inferior spark plug coil or transistor etc) could, combined with that lower voltage, cause misfire.

But why was only cylinder #1 misfiring with all the other parts good/the same as on the other cylinders?

Thanks
 
#16 ·
But why was only cylinder #1 misfiring with all the other parts good/the same as on the other cylinders?
I honestly can't answer that, maybe Cylinder 1 has a slightly higher compression than the rest requiring a slightly higher Firing Voltage, so that one will show up first, then as the VT gets worse, you would get Multiple Misfire Codes as before ??

I dunno :confused: :laugh

Just an un proven theory :wink

Re those Cam Caps, they simply crack, may have been a bad batch, but I've personally seen 2 now, and heard of others...........

The same model year but different model V12 cars and always number 2 cap :wink

Cheers Dave
 
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