Help! CL 600 2008 low on power, but no fault codes.

Tabraze Akram

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Help?
I have a 2008 CL600 V12 with 80,000 miles.
I had it dyno tested and it came back with only 370BHP. That’s quite a drop from the stock 517BHP!
I recently had an engine misfire, however managed to repair the coil pack. Now no fault codes.
The car has new oil, new gear box oil, new diff oil, new plugs and new air filters.
Its still fast, but not 500BHP fast, and no fault codes. Also power drops sometime while driving?
Any ideas?
 

V6Matty

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Welcome, lovely car
I think your only option would be to go to an Indy that knows the V12 engines, it sounds like the only way your going to be able to diagnose the shortfall is if you do live data from STAR
 

peterws1957

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^ This exactly, otherwise you could be guessing and throwing away cash. Perhaps no fault codes suggests a gearbox problem? There's at least one forum member on here who knows everything about V12's so hopefully he will give some input.

Incidentally on the subject of V12 coilpacks, I've just come across You Tuber Clark Rupp who goes into some detail on this subject, including X Rays of original MB packs and comparison to "replacement" packs and the reasons why they don't work or quickly fail. Well worth a look.
 
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Tabraze Akram

Tabraze Akram

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^ This exactly, otherwise you could be guessing and throwing away cash. Perhaps no fault codes suggests a gearbox problem? There's at least one forum member on here who knows everything about V12's so hopefully he will give some input.

Incidentally on the subject of V12 coilpacks, I've just come across You Tuber Clark Rupp who goes into some detail on this subject, including X Rays of original MB packs and comparison to "replacement" packs and the reasons why they don't work or quickly fail. Well worth a look.
Thanks!
Yes I’ve seen this video and ordered some new coils. Was gonna attempt it myself but my local garage gave it a try. After a few weeks of driving all got and no fault codes.
It’s an expensive part? £1200! There have been lots of up-issues if the part however my research shows the electronics have not changed, only the sealing of the unit. The coil covers are the weak links.
I’d recommend a repair before replacing.
 
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Tabraze Akram

Tabraze Akram

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^ This exactly, otherwise you could be guessing and throwing away cash. Perhaps no fault codes suggests a gearbox problem? There's at least one forum member on here who knows everything about V12's so hopefully he will give some input.

Incidentally on the subject of V12 coilpacks, I've just come across You Tuber Clark Rupp who goes into some detail on this subject, including X Rays of original MB packs and comparison to "replacement" packs and the reasons why they don't work or quickly fail. Well worth a look.
Thanks, lover the car!
I have recently had the voltage regularly and main battery replaced. The stater battery was new already. So was wondering if this may have caused an issue?
But it’s puzzling there are no fault codes? I’m hesitant to shell out for a specialist to plug an OBD2 and tell me which I already know.
I think your right l, take it to a V12 specialist.
Any suggestions in the UK?
 

daveenty

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Whilst not exactly being next door to you, Mercland at Nuneaton knows these engines well, having owned more than their fair share. That's certainly who I'd be contacting anyway, with the added bonus that the owner, @jaymanek, is a long-standing member on here.
 
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Tabraze Akram

Tabraze Akram

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are you sure it has ever been at full power Tabraze ??
It’s a fair point. When I brought the car in Jan went with a mate in a 17 plate M3. Let say it was on par in the way home ;)
 
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Tabraze Akram

Tabraze Akram

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Whilst not exactly being next door to you, Mercland at Nuneaton knows these engines well, having owned more than their fair share. That's certainly who I'd be contacting anyway, with the added bonus that the owner, @jaymanek, is a long-standing member on here.
Much Appreciated!!
I’ll get in touch
 

bembo449

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It’s a fair point. When I brought the car in Jan went with a mate in a 17 plate M3. Let say it was on par in the way home ;)
ok ;) thought I would ask pal , keep us up to date on wether you find the cause of the issue , id be upset if I lost nearly half my 300 ponnies
 

alexanderfoti

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At a guess:

Boost leaks
Air in IC pump system or IC pump fault.

Both most likely, but the list is very long!
 
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Tabraze Akram

Tabraze Akram

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At a guess:

Boost leaks
Air in IC pump system or IC pump fault.

Both most likely, but the list is very long!
Thanks!
Any details where to check?
Also no fault codes so far
 

alexanderfoti

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Thanks!
Any details where to check?
Also no fault codes so far

Intake air temp actual values

boost leak testing is carried out by smoke testing the intake system
They won't log low boost codes or high IAT codes unless the turbos are essentially disconnected.
 
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Tabraze Akram

Tabraze Akram

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IC pump ?
Thanks!
I’ll check it out. The IC coolant level is fine but I suspect there may be bobbles in the system.
Intake air temp actual values

boost leak testing is carried out by smoke testing the intake system
They won't log low boost codes or high IAT codes unless the turbos are essentially disconnected.
Thanks!
Do you any pics or videos on how to check?
 

pillow

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If you have a Bluetooth obd connector then you can use the Torque app on your phone to check these two things.

Intake air temperature should vary but should always drop when you accelerate. Mine usually goes as high as 60c off throttle or when idling on a warm day but then drops to mid 30s when I plant the right foot.

Boost pressure can also be measured in app and should peak around 15psi (at least mine does and mine feels fine)

Really you want access to STAR. I got mine about a year ago and has been invaluable to me getting my car running right.
 
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Tabraze Akram

Tabraze Akram

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If you have a Bluetooth obd connector then you can use the Torque app on your phone to check these two things.

Intake air temperature should vary but should always drop when you accelerate. Mine usually goes as high as 60c off throttle or when idling on a warm day but then drops to mid 30s when I plant the right foot.

Boost pressure can also be measured in app and should peak around 15psi (at least mine does and mine feels fine)

Really you want access to STAR. I got mine about a year ago and has been invaluable to me getting my car running right.
That’s great. I’ve got an Actel OBD2 reader. I’ll give it a go and let you know how it get on.
 

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