Multiple Random Misfire
Thread Starter
Junior Member
Joined: May 2018
Posts: 44
Likes: 15
From: Sydney, Australia
2007 clk350 coupe, 2013 C250 coupe, 2013 C250 wagon
Multiple Random Misfire
Seeking help, please. 2007 CLK 350, 90k klm (55k miles).
Have just installed a new inlet manifold as I intend keeping the CLK for many years and so changed it out as I was getting "stuck flap" codes.
Job went fine, as per WIS - but on start-up after the job it revs high (2000 rpm) then staggers into multiple misfires (sounds like running on about 3 cylinders) and stalls. I get codes 0300, 0301, 0305, 0306 etc. - All misfire codes.
Things I did along the way during the install that were extra to the WIS:
Before I start pulling bits apart (again) next weekend I would greatly appreciate your advice!
Have just installed a new inlet manifold as I intend keeping the CLK for many years and so changed it out as I was getting "stuck flap" codes.
Job went fine, as per WIS - but on start-up after the job it revs high (2000 rpm) then staggers into multiple misfires (sounds like running on about 3 cylinders) and stalls. I get codes 0300, 0301, 0305, 0306 etc. - All misfire codes.
Things I did along the way during the install that were extra to the WIS:
- Disconnected battery beforehand as I thought safer (less fire risk)
- Cleaned MAF sensor with spray MAF cleaner
- Cleaned throttle body with throttle body cleaner (I rotated the butterfly during this procedure)
- Cleaned injectors on the outside with throttle body cleaner.
- Cleaned injector connectors with contact cleaner spray.
- Before startup I turned key to ignition (no start) to prime fuel to the rail/injectors twice.
- I must not have seated the manifold properly - but I was very careful and inspected pretty thoroughly after torquing down with an inspection mirror.
- Injector cleaning has caused trouble of some sort.
- Rotating the throttle body butterfly needs some sort of reset.
Before I start pulling bits apart (again) next weekend I would greatly appreciate your advice!
MBworld Guru
Joined: Dec 2009
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NO LONGER ACTIVE
It could be a vacuum leak, so check for that. The gaskets can be a challenge to keep seated. It could also be that the rive--by-wire throttle needs to be synchronized. Try this:
1. Make sure everything in the car is turned off and closed.
2. Turn the key to position 2 so all the dash lights are illuminated.
3. Press the accelerator fully to the floor, depressing the "kick-down" button.
4. Hold he pedal for 5 seconds and continue to hold it down.
5. Turn the ignition switch back one click to position 1.
6. Release the accelerator pedal, but leave the key in position 1.
7. Sit quietly and wait for about two minutes - do NOT open or turn anything on.
8. Listen for a "click" or "ping" noise form the dash.
9. Start the engine and drive the car for at least five minutes.
If that doesn't work, you may SDS to check codes and use it to do the re-sync.
1. Make sure everything in the car is turned off and closed.
2. Turn the key to position 2 so all the dash lights are illuminated.
3. Press the accelerator fully to the floor, depressing the "kick-down" button.
4. Hold he pedal for 5 seconds and continue to hold it down.
5. Turn the ignition switch back one click to position 1.
6. Release the accelerator pedal, but leave the key in position 1.
7. Sit quietly and wait for about two minutes - do NOT open or turn anything on.
8. Listen for a "click" or "ping" noise form the dash.
9. Start the engine and drive the car for at least five minutes.
If that doesn't work, you may SDS to check codes and use it to do the re-sync.
Thread Starter
Junior Member
Joined: May 2018
Posts: 44
Likes: 15
From: Sydney, Australia
2007 clk350 coupe, 2013 C250 coupe, 2013 C250 wagon
Rodney,
Thanks for the quick response - much appreciated. Just now I tried the drive by wire re-synch you suggested, but to no avail. I pulled the codes again after the re-start and got misfires on 1,3,2. This leads me to think that I've misaligned the gasket on the right bank. I recall I had to probe one of the centre bolt holes on that bank to get the bolt started - so I may have misplaced the gasket inwards doing this. Come the weekend I'll pull it out and see. Will let you know how I go. Thanks again for your kind help.
Thanks for the quick response - much appreciated. Just now I tried the drive by wire re-synch you suggested, but to no avail. I pulled the codes again after the re-start and got misfires on 1,3,2. This leads me to think that I've misaligned the gasket on the right bank. I recall I had to probe one of the centre bolt holes on that bank to get the bolt started - so I may have misplaced the gasket inwards doing this. Come the weekend I'll pull it out and see. Will let you know how I go. Thanks again for your kind help.
Thread Starter
Junior Member
Joined: May 2018
Posts: 44
Likes: 15
From: Sydney, Australia
2007 clk350 coupe, 2013 C250 coupe, 2013 C250 wagon
I removed the manifold and as I suspected I had shifted the centre section of the gasket on the right bank when installing. Used another set of new gaskets with a few drops of silicone gasket in the locating tabs this time to keep the gaskets in place and re-installed. Vacuum leak gone and (this) misfire solved. I say "this" misfire as before I started on the inlet manifold replacement I had been getting an intermittent CEL and misfire (p0352). I'll make that the subject of a different thread so anyone searching has a better chance of finding their subject. Thanks again Rodney on this one.
