CLK 320 missfire / running rough

D

Dave 1966

Guest
Greetings, its a W208 320 CLK, on a W plate, 90k miles.
I have had a miss-fire problem for a while, where one or more cylinders would drop out under hard acceleration. To clear it, you simply turn off the ignition, restart and away you go (this could be done on the move, but not ideal if you're trying to overtake someone...). If the car was used for a long run (100+ miles), it would be a whole lot better, although the fault could be reproduced if you try hard enough. Over a period of time doing short journeys to work (4 miles each way), it would get progressivley worse. When the fault was reproduced, it was proved to be different cylinders that would drop out by removing the leads to the coil packs. I was advised that perhaps the fuel filter could do with a change, complete with the pressure regulating valve inside it.
As a side issue, the battery was on it's last legs and was losing charge.
The fuel filter was changed and the car started to make sure all was ok. It ran ok, and appeared to rev ok.
The battery was then changed. It now runs like a sack of.... It starts on all six, but then almost immediatley drops down onto three. But it will always be a different three. No apparent pattern. Gradually increasing the revs, it will run on all six from about 3000rpm upwards. The fuel lines have been flushed through, as the petrol that came out of the fuel filter was black, just in case.

A contact at Mercedes has now advised changing the plugs, leads and coil packs, but as each coil pack is about £200 (x6), then there are the 12 spark plugs (not cheap), and leads on top, I thought I would seek further advise before blowing a whole pile of cash.

Please please please some one help......
 

Cole@MBS

Forum Supporter
Authorised Forum Supporter
Joined
Dec 1, 2008
Messages
13,625
Reaction score
763
Age
51
Location
Hedge End, Southampton
Website
www.mbssouthampton.co.uk
Your Mercedes
124 300 CE 24 Coupe, C220CDI, 1959:Morris Minor
Seen it many times before, new battery frys the air-mass sensor, also jump starting causes this fault,

Welcome to the forums!
 
OP
D

Dave 1966

Guest
  • Thread Starter
  • Thread starter
  • #3
Thanks, I take it you are referring to the MAF. And would this have been the cause of the problem prior to the battery swap?
 
Last edited by a moderator:

shane10010

Active Member
Joined
Apr 28, 2009
Messages
27
Reaction score
0
Location
Northampton, United Kingdom
Your Mercedes
Mercedes S500 Coupe (current), CLK320, Vectra SRI, Jaguar X-Type, Audi 200T, Mercedes 280SE
W208 CLK320 Misfire

Hi, Looks like I have your cars relative! Mine is the same model/year and has the same problem. Great car but this intermittent misfire is doing my head in!!

Looking at a couple of MB Forums, the recurring 'solutions' seem to be:

- MAF
- Fuel Filter/pump
- Coil pack/s
- Leads
- Plugs
- Fuel Pressure regulator
- O2 (Lambda) Sensor
- Damaged Catalytic converter (higher rpm and backpressure leads to misfire)

It would seem that you have done the filter while I have done the plugs and lead on teh offending coil (cyl 4 in my case).

Looking at what others, you and I have done what I intend doing is:
- Visit the exhaust centre in the morning and getting some advice on the cats
- Depending on the above, replacing the Fuel Pressure Regulator

I will keep you posted on updates and would appreciate you doing the same.

Good luck!
 
OP
D

Dave 1966

Guest
  • Thread Starter
  • Thread starter
  • #5
Well I'm glad to say that, in the main, all is well.
Following the advise above, I managed to borrow a MAF from MB, and hey presto, it will now run on all 6, and when I give it a boot-full, it doesn't cut cylinders. (When the fuel filter was changed the fuel that drained back was the wrong shade of black, and the theory we have is that when using full beans, the blocked fuel filter was restricting the flow of fuel to the engine, so the smart-@rse brain shut down a couple of cylinders.)

It still has a problem of running slightly lumpily, and connecting a scanner shows that cyl 5 is occassionally missing, but it has been doing this for a long time, even after the plugs were changed at the last service and the coil packs swapped around. It doesn't use oil at all, so is this going to be an injector fault?

The odd miss-fire aside, what I need to do now is get used to the performance again. Now all 6 cylinders are getting a full slug of fuel, it's taking off like a rocket, with the fuel consumption to suit!!!!

Thanks for the help,

Dave.
 

shane10010

Active Member
Joined
Apr 28, 2009
Messages
27
Reaction score
0
Location
Northampton, United Kingdom
Your Mercedes
Mercedes S500 Coupe (current), CLK320, Vectra SRI, Jaguar X-Type, Audi 200T, Mercedes 280SE
Hi Dave,

Done my fuel filter but no improvement.
The miss starts just over 4000rpm then like yours, doesn't stop until I switch off and restart.
Considering replacing the MAF although if I google, replacing the HT leeds comes up as a frequent solution. Also, I have seen two articles referring to an engine remap?

Willl try get the MAF done over the weekend and update. Let us know how you get on.
Cheers!
 

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
331
Age
86
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
Hi Dave,

Done my fuel filter but no improvement.
The miss starts just over 4000rpm then like yours, doesn't stop until I switch off and restart.
Considering replacing the MAF although if I google, replacing the HT leeds comes up as a frequent solution. Also, I have seen two articles referring to an engine remap?

Willl try get the MAF done over the weekend and update. Let us know how you get on.
Cheers!

Pull the wire plug of the MAF and try it, ignore possible rough idle, and see if it goes better
 

busby20

Active Senior Members
Joined
Mar 22, 2007
Messages
223
Reaction score
0
Location
Glasgow
Your Mercedes
SLK's 2, CLK320 Cabriolet.
Greetings, its a W208 320 CLK, on a W plate, 90k miles.
I have had a miss-fire problem for a while, where one or more cylinders would drop out under hard acceleration. To clear it, you simply turn off the ignition, restart and away you go (this could be done on the move, but not ideal if you're trying to overtake someone...). If the car was used for a long run (100+ miles), it would be a whole lot better, although the fault could be reproduced if you try hard enough. Over a period of time doing short journeys to work (4 miles each way), it would get progressivley worse. When the fault was reproduced, it was proved to be different cylinders that would drop out by removing the leads to the coil packs. I was advised that perhaps the fuel filter could do with a change, complete with the pressure regulating valve inside it.
As a side issue, the battery was on it's last legs and was losing charge.
The fuel filter was changed and the car started to make sure all was ok. It ran ok, and appeared to rev ok.
The battery was then changed. It now runs like a sack of.... It starts on all six, but then almost immediatley drops down onto three. But it will always be a different three. No apparent pattern. Gradually increasing the revs, it will run on all six from about 3000rpm upwards. The fuel lines have been flushed through, as the petrol that came out of the fuel filter was black, just in case.

A contact at Mercedes has now advised changing the plugs, leads and coil packs, but as each coil pack is about £200 (x6), then there are the 12 spark plugs (not cheap), and leads on top, I thought I would seek further advise before blowing a whole pile of cash.

Please please please some one help......

Had this problem, replaced all the leads for a total of just over £35, car runs perfect. Did look at coils, american company on e-bay was supplying a "pack" of 6 for under £300 - tempted, but decided to try the cheap route - which worked.
 

shane10010

Active Member
Joined
Apr 28, 2009
Messages
27
Reaction score
0
Location
Northampton, United Kingdom
Your Mercedes
Mercedes S500 Coupe (current), CLK320, Vectra SRI, Jaguar X-Type, Audi 200T, Mercedes 280SE
Hi Malcolm and Busby20.
Thank you for the replies and advice, just wish I had read them BEFORE changing the MAF!

I drove around Northampton this morning and the two Bosch fuel injection specialist I found on Google were both closed. Ended up buying and installing a new Bosch unit from Central Auto Supplies for £138 and you can guess the outcome.

The car goes into the panelbeater for some cosmetic surgery this week so will check the bank balance and follow the HT Lead route unless there are any other suggestions?

Thank you again and enjoy the long weekend.
Shane
 

Cole@MBS

Forum Supporter
Authorised Forum Supporter
Joined
Dec 1, 2008
Messages
13,625
Reaction score
763
Age
51
Location
Hedge End, Southampton
Website
www.mbssouthampton.co.uk
Your Mercedes
124 300 CE 24 Coupe, C220CDI, 1959:Morris Minor
Sounds like water in the fuel rail, seen that a few times now, remove the rail, wash out with carb cleaner, wash tops off injectors with the cleaner, grease the "o" rings before refitting!
 

shane10010

Active Member
Joined
Apr 28, 2009
Messages
27
Reaction score
0
Location
Northampton, United Kingdom
Your Mercedes
Mercedes S500 Coupe (current), CLK320, Vectra SRI, Jaguar X-Type, Audi 200T, Mercedes 280SE
misfire solved?

When I bought my machine, I decided to add fuel injection system cleaner and have been using the 'add per tank' size at each fill. for the last two fills, I have used Premium unleaded and not added anything.

The misfire has gone but I still had static on the radio which sounded like a suppression problem.

On changing the leads, I found that one was corroded and another was the wrong part number. Having cleaned, greased and replaced the leads and connectors I no longer have any crackle or misfire!!

Problem solved!!

:D
 

TWOBARROWS

Member
Joined
May 3, 2010
Messages
16
Reaction score
0
Location
FLEET, HANTS, UK
Your Mercedes
'87 500SL (For sale) '99 CLK rag top, 04 JEEP Gnd Cherokee
I had exacly the same problem on my '99 230 CLK when I first bought it last year, every day going to & from work it would go into rough runnning & sound like it had a blowing exhaust. Turning it off & on again sorted it every time. Garage fixed it, but now nearly a year later it has started again!! Fuel filter was replaced around 5k miles ago, it's had an oil change etc (100k miles). So could any of the above components really cause this problem, I am confused as the symptoms disappear everytime it is switched off & on again.
Cheers.....
 

TWOBARROWS

Member
Joined
May 3, 2010
Messages
16
Reaction score
0
Location
FLEET, HANTS, UK
Your Mercedes
'87 500SL (For sale) '99 CLK rag top, 04 JEEP Gnd Cherokee
I pulled the MAF yesterday, looked clean (looked new actually, maybe that was replaced last year), but cleaned it with Isoprop.Alc. & put back. Went out on a short non motorway trip later & had the same problem, lifted bonnet & pulled the connectors above the fuel rail one by one, pot 2 (from front to back) didn't make any difference, but the others caused it to nearly stall when pulled. Been out today & had another couple of incidents, each time it's been pot 2, so I guess it's the coil? Can this be easily swapped around to isolate?
Any help appreciated.........
 

TWOBARROWS

Member
Joined
May 3, 2010
Messages
16
Reaction score
0
Location
FLEET, HANTS, UK
Your Mercedes
'87 500SL (For sale) '99 CLK rag top, 04 JEEP Gnd Cherokee
I guess the connectors I was pulling were for the injectors? Anyhow, found the spark plugs & two coil packs :) Removed plugs, probably the cleanest have ever seen plugs!!! Swapped the two coil packs so I just need to see if the fault moves. Watch this space.....
Incidentally I torqued the plugs to 26 Nm & the coils to 6Nm, can't remember where I saw that info. but thought I'd post it anyhow.
 

TWOBARROWS

Member
Joined
May 3, 2010
Messages
16
Reaction score
0
Location
FLEET, HANTS, UK
Your Mercedes
'87 500SL (For sale) '99 CLK rag top, 04 JEEP Gnd Cherokee
Well the fault has moved to pot 4 now, so it's the coil-pack. Are the bosch ones the best, they both have a crack in them & seem to be stupidly expensive? What, if any other brands should I consider?
 

kraM

Member
Joined
Nov 21, 2010
Messages
14
Reaction score
6
Location
Berkshire
Your Mercedes
1999 CLK 340
Hi,
I have a very similar problem. I know nothing about this model, but the Mother-in-Law has just brought a 1999 CLK 340 SPORT Auto. - Well that what it is badged as, but I can't another model like this, so it may be a 320.

Sometimes it runs well, but it has never been that quick. Now it tops out at 20mph, missing really badly, and probably running on 2 of it's 6.

And guess who has been tasked to fix it?!? :)

I know it is impossible to say for sure, but I was going to change the plugs, until I found out it had 12 of them, and they cost a fortune, then I heard that the coild packs go, the leads break down etc.

Going through the above, it looks like the MAF could be the culprit, although the history of the car shows the plugs last being changed in 2005, with a fuel pump and filter not so long after that...
My Father-in-law has a E240,

???will his MAF fit mine (i.e. a quick check)???

And if that doesn't fix it, what would you reccomend changing first, as budget is serverly limited...

Thank you very much for your time,

Mark
 

TWOBARROWS

Member
Joined
May 3, 2010
Messages
16
Reaction score
0
Location
FLEET, HANTS, UK
Your Mercedes
'87 500SL (For sale) '99 CLK rag top, 04 JEEP Gnd Cherokee
As far as I can gather, you can disconnect the MAF as a diagnostic step, assuming everything else is working OK then it will run a little less efficient and maybe a bit rough, but it should run. I would guess you disconnect it before starting.

As I understand it, the failure mode of the coil packs is that the Engine Control Unit detects a misfire & switches off that cylinder to prevent damage to the Cat? Maybe someone could correct me or elaborate.

Failing coil packs seems to be a common problem on these, so I am not sure whether I should be replacing with Merc / Bosch or another brand. I have seen Bosch for 73.08 and another brand for 25, one hell of a difference!
 

kraM

Member
Joined
Nov 21, 2010
Messages
14
Reaction score
6
Location
Berkshire
Your Mercedes
1999 CLK 340
Nice one, tomorrow will be hopefully a cheep one...

Thak you,

Mark
 

TWOBARROWS

Member
Joined
May 3, 2010
Messages
16
Reaction score
0
Location
FLEET, HANTS, UK
Your Mercedes
'87 500SL (For sale) '99 CLK rag top, 04 JEEP Gnd Cherokee
After the parts not appearing, I sent an email to the company & got a very nice phone call the next morning from the owner of the company!
Well I fitted 2 new coil packs tonight, quick test drive proved them fine, will drive to work tomorrow which is nearly 30 miles so should be a good test.
Incidentally, the wsebsite has some useful help pages explaining what some ingition components do:
http://www.probedistributors.co.uk/Content.aspx?page=Ignition Problems Help
 


ACMS Mercedes Ltd is an independent Mercedes-Benz service specialist based in Walsall. The company provides high levels of customer service and quality workmanship, at competitive prices. Call Mark on 01922 634666 or 07530 456000
Top Bottom