CL500 (2000) Misfire

[kelticcare]

Having trouble with misfire that dealer has not been able to solve.
Codes say misfire cylinder 1, and MAF sensor fault. Dealer has:
Changed MAF sensor
Swapped plugs, coils etc, still says cylinder 1
Swapped fuel injectors, ditto
Compression test OK
Initially misfired when accelerating hard, but now much worse.
I have car back again from the garage, with maybe its the ECU?
Anyone any ideas
Thanks

 

[Shude]

I'll be fascinated to find out the answer to this question!

http://www.mbclub.co.uk/forums/showthread.php?t=12235

I'm getting more convinced that this problem is down to fuelling.

 

[imadoofus]

Sounds very similar to my coupe's recent trauma.

Started off as a mild misfire (more of a hesitation) and uneven idling. MAF was checked, as were OVP, crank sensor, injectors and coil packs.

Eventually, STAR diagnosed an ECU fault. I got it fixed, replaced the coil packs (apparently the coil packs can start to break down, causing a surge back the ECU which blows it, so not replacing them is short-sighted), and all seems almost back to normal.

The car was sat for three weeks before I got the ECU in, and I've only driven it about ten miles since, and at first it seemed little changed, but now it's improving with every mile driven.

PJ

 

[rajinder_1]

i had issues with missfire, get the petrol checked. i found this out the long way. Make sure they take fuel out from the injection rail into a container.

My mechanic opened the nozzel and had another guy turn the ignition to pump the fuel into the container found loads of goo in it....

Raj

 

[mb240]

Buy better quality fuel and go for a long drive?

I'll be fascinated to find out the answer to this question!

http://www.mbclub.co.uk/forums/showthread.php?t=12235

I'm getting more convinced that this problem is down to fuelling.

I think you are right.

I filled up in Tesco in Dublin (which is supplied by Statoil here) and last week and this week on two separate occasions my CLK55 misfired. It only happened when I went to kick down, and then started to wobble like a 1920s plane. Furthermore, when stopped with this happening, the idle was very rough (you could feel it through the brake pedal). This all went when restarted, so I drove home and left it as I was away for weekend.

Came back yesterday, same thing, no problems until putting the foot down, the misfire putt-putt-putt with a big drop in power. Stopped, restarted and it was gone.

Anyway, after reading the forums, it seemed that the simplest first step was fuel, then plugs (changed 6000km ago) and then leads, etc., before thinking crazy things like the CAT, etc., .

So I filled up with V-Power (it is 95RON in Ireland but has engine cleaning stuff apparently), on top of a quarter of a tank of the Tesco stuff, and went for a 120km spin, and basically now it's silky smooth, and kickdown is clean all the way to the redline, including the change up (but not too many, as it will do 240kph in 4th gear!).

So, I am thinking, dodgy fuel by Tesco, they must water it down in some way, as it is cheaper by far here. I couldn't kickdown without a misfire yesterday and having gone through the 15 litres of what was left, and another 15 litres or so all in one trip, I am having no problems.

Also, I never got any engine management lights, or check engine, etc., at all, not a single error or warning.

 

[BlackC55]

Due to it not having a return to the tank the fuel rail can accumulate water. This must be drained first. Change the fuel that you are using too. Also try a cylinder leakage test too. Your garage should have the equipment for testing that too. If it is still doing it it will probably be an ECU problem. They are not cheap!!!!!

 

[kelticcare]

Thanks for advice, thought I'd update you with final outcome.
Dealership detected 2 faults.
1. Faulty Air Mass Sensor. Replaced. (£505.58)
The next one took a bit of getting to:
Removed Coil and plugs and swapped with good cyl, removed fuel rails (injectors partially seized), checked compression, removed exhausts and checked cats, etc etc. No change
2. Checked ECU, heavy corrosion around ECU pins with water ingress. Cleaned pins etc, fault still there. Replaced ECU and misfire gone. Hallelujah.

Then the painful bit. £2030.68, and that was restricted!! Mercedes here charge £82.50/hour + VAT, and this was restricted to £50 + VAT.
Now only frustration is that garage searched history of car and this has been a recurring problem for the last few years.They showed me the diagnostics dating back to 2003, when the car was in warranty, and they believe it has been the same problem ever since. Bugger!
Thanks again
John

 

[rajinder_1]

if that has been reoccuring since then you shouldnt pay that much, especially if they hadnt resolved prior

 

[kelticcare]

Different dealer, different owner. I bought the car 2 months ago, private sale, from Bristol area. Took it to Inverness but had not used kickdown until cash had changed hands. I know, I know, git!

 

[rajinder_1]

surely though, if its a issue that been ongoing and it would have had money spent on it being diagnosed etc, im pretty sure that you should be able to argue a bit and get some cas knocked off, ask some of the other members they are pretty hot on stuff like this...

Raj

 

[normanr]

Hi kelticcare

I don't class you as a GIT, the trouble with buying a second hand car is you never know what a basic problem can turn into.

The problem now days is they are so sophisticated regards the electrics, I bought a C-Class that sometimes when it was started it would not accelerate, turn ignition off and start again and it was fine, I made some enquires before buying and was advised it was probably a sensor so no big deal.

I had the thing for 3 weeks and the problem got worse and I ended up getting a new ECU cost me £1700.00 with stealers fitting and setting up charge.

So to sum up we all take a chance when buying seconhand it's called luck of the draw.

Norman

 

[smoothcoupe]

posible remedy

i had the same problem with my 500 coupe (140).. it turned out to be the cats after spending 4 grand on everything else.

 

[amwebby]

I've had the same problem intermittently, always caused by using the kickdown on entering motorways. Just recently a colleague confided to me that V-Power was a marketing exercise, to save my money and use regular 95 RON petrol.

So, I have since filled up with Shell 95 RON three times and BP 95 RON once. In all those miles of driving, (4 tankfuls equals around 1,600 miles), I have not experienced one recurrence of the problem.