Cl 500 2009 Rough Idle P0305
11-10-2022, 07:21 AM
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CL 500
Cl 500 2009 Rough Idle P0305
Please forgive me for the long explanation but i wanted to explain the issue in details
In 2013 I bought a CL500 2009 with 40000 KM Kept the car in good working order and did all the required services and oil changes at the Mercedes local dealer.
Last year suddenly the car misfiring so took it to the dealer they said its a bad spark plug and replaced it.
two months later the car misfiring again so this time i decided to replace all spark plugs and Ignitions coils since i already drove the car another 120000KM .
I ordered Delphi Ignition Coils and Bosch spark plugs. During the install I noticed piston 5 old spark plug gap almost closed.... Strange !
Anyway I replaced the spark plugs and coils and the car run flawless again for a years during that time i drove the car approximately 30000KM.
Suddenly the same issue start to happen again and I noticed if i turn the car off and on again the rough idle will go away.
With time it started to happen more and more even started to happen during driving suddenly the engine will shake the whole car . luckily and strangely turning the car on off will eliminate the problem!
I decided to order another set of Coils (Bosch) and spark plugs and I also got new injectors.
During the install I noticed piston 5 spark plug with closed gap again ! I installed the new coils and spark plugs and car run smooth again this time for 3 months only ! I drove less than 6000km with second set of coils and plugs.
Now I'm convinced there is something seriously wrong it cant be the coils or the spark plugs again!
Immediately removed piston 5 spark plug but the gap was perfect. I put back the spark plug and try to start the car but car wont start now !
I remove the piston 5 spark plug and now strangely the gap is closed ! I replaced the plug the car now starts but rough idle ; I tested piston 5 coil and spark plug and found them in good working order so I assumed its a bad injector .
Since I already have new injectors I decided to install them and the car was perfect again problem solved switched off the car and decided to take it the morning for a test drive .
Next day started the car for the test drive but to my surprise the car is misfiring again !!!
Gave up and asked the local debar to take the car and try to fix it .
They found bad vacuum hoses and replaced them the car run better but didn't fix the problem!
They did a compression and leak test and they wanted to take the engine out because piston 5 was with the lowest pressure 11 bar and highest leak @ 12 % .
I was not convinced that was the problem cos i still believe 11 Bar pressure was good enough for 2009 W216 with over 200000KM. Other pistons were between 11.5 to 12.5 Bar & Leak between 6 to 9 %
Then they suggested to do intake flush cos there was lots or carbon build up on the valves . I said ok but sadly the car was still the same .
Then the dealer notice leak from the intake manifolds and suggested to replace the gaskets. When they removed the intake manifolds they notice a problem and they fixed it and reinstalled the intake and still the same problem !
The dealer believe the problem to be in the Piston 5 Cylinder head and they want to remove the engine .
Any suggestion ?
TIA
In 2013 I bought a CL500 2009 with 40000 KM Kept the car in good working order and did all the required services and oil changes at the Mercedes local dealer.
Last year suddenly the car misfiring so took it to the dealer they said its a bad spark plug and replaced it.
two months later the car misfiring again so this time i decided to replace all spark plugs and Ignitions coils since i already drove the car another 120000KM .
I ordered Delphi Ignition Coils and Bosch spark plugs. During the install I noticed piston 5 old spark plug gap almost closed.... Strange !
Anyway I replaced the spark plugs and coils and the car run flawless again for a years during that time i drove the car approximately 30000KM.
Suddenly the same issue start to happen again and I noticed if i turn the car off and on again the rough idle will go away.
With time it started to happen more and more even started to happen during driving suddenly the engine will shake the whole car . luckily and strangely turning the car on off will eliminate the problem!
I decided to order another set of Coils (Bosch) and spark plugs and I also got new injectors.
During the install I noticed piston 5 spark plug with closed gap again ! I installed the new coils and spark plugs and car run smooth again this time for 3 months only ! I drove less than 6000km with second set of coils and plugs.
Now I'm convinced there is something seriously wrong it cant be the coils or the spark plugs again!
Immediately removed piston 5 spark plug but the gap was perfect. I put back the spark plug and try to start the car but car wont start now !
I remove the piston 5 spark plug and now strangely the gap is closed ! I replaced the plug the car now starts but rough idle ; I tested piston 5 coil and spark plug and found them in good working order so I assumed its a bad injector .
Since I already have new injectors I decided to install them and the car was perfect again problem solved switched off the car and decided to take it the morning for a test drive .
Next day started the car for the test drive but to my surprise the car is misfiring again !!!
Gave up and asked the local debar to take the car and try to fix it .
They found bad vacuum hoses and replaced them the car run better but didn't fix the problem!
They did a compression and leak test and they wanted to take the engine out because piston 5 was with the lowest pressure 11 bar and highest leak @ 12 % .
I was not convinced that was the problem cos i still believe 11 Bar pressure was good enough for 2009 W216 with over 200000KM. Other pistons were between 11.5 to 12.5 Bar & Leak between 6 to 9 %
Then they suggested to do intake flush cos there was lots or carbon build up on the valves . I said ok but sadly the car was still the same .
Then the dealer notice leak from the intake manifolds and suggested to replace the gaskets. When they removed the intake manifolds they notice a problem and they fixed it and reinstalled the intake and still the same problem !
The dealer believe the problem to be in the Piston 5 Cylinder head and they want to remove the engine .
Any suggestion ?
TIA
