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Discussion Starter #1
I've been dealing with this car misfiring since i got it. I've replaced the coil packs and plugs on both sides. While just replacing the passenger side I noticed a vacuum line not attached to anything. I tested and there was no vacuum. I found 2 brackets with ???? and vacuum lines running off of them right near the right side coil pack. One did not have a vacuum line attached to it. So I attached one the 3 way lines (that just had a hanging line) to the second sensor(?) (don't know what these 2 things are)

Long story short.. still having issues and there have been so many people messing with this engine that I'm not sure about what is going on with the vacuum lines.

Does anyone have pictures of the vacuum lines and where they come from and to (hither and yon) :)

Tired of just putting new coil packs on and not having it fix the issue. I also am failing emissions HIGH HC, CO AND NOx... it really smells bad because of the misfiring I imagine.

Thank you
 

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W164 GL450, W221 S550, R230 SL600TT, R170 SLK230, W140 S500, More
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When replacing the coilpacks, did you get rebuilt by Clark? He does excellent work. At that time, did you replace the spark plugs as well? Did you use the exact spark plug (24 of them, LOL) that came with the car when new? I have the owners book that came with my SL600 and absolutely use Only the exact same spark plug specified in there. Positively no substitute! Turbo engines must have Iridium plugs only. No need to gap them, they are ready to use right out of the box.. Any time replacing coil packs on these things it's crazy to keep using the old plugs. Don't drive it with the engine misfiring!!!!
 

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W164 GL450, W221 S550, R230 SL600TT, R170 SLK230, W140 S500, More
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It's important to use the right spark plugs on these engines. (NGK Iridium) Also, Clark has the transformer that sits atop the engine and you can buy one of those from him and try swapping that out as a troubleshooting method for that, and if it doesn't fix the issue he takes them back with a restock fee I think $50 or $100 so you've really "rented" it as a troubleshooting method, and that way you can see if it is the transformer that's the problem. If both coil packs are either new or rebuilt and still misfire, maybe the problem is the transformer. His website is something like V12icpack dot com, you could google Mercedes V12 coil packs rebuild and probably find him, he is Clark in California, the world's authority on the ignition systems for these Benz V12s, his website full of knowledge and videos, shows he knows these things inside and out. His rebuilt parts are better than what the car came with when new, due to technology of the parts. Often if you have one coilpack go bad it's possibly partially caused by old spark plugs with the gap increasing in size as time goes by and the effort needed to make the spark jump, is harder on the coilpacks so they give out. One side of my engine did just that so when replacing that coilpack I changed all the spark plugs and with some luck my other side may last a lot longer now. Time will tell but this car couldn't possibly run any better now! I am expecting the other side coilpack to NOT break now since I've got all new spark plugs. People wait too long to change spark plugs on these cars because there are 24 of them and they cost about $15 each, and old spark plugs are a bad thing! Good luck! A rebuilt coilpack cost around $750-800 from Clark. But well worth it.
 

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2005 SL65 plus 13 other non MB toys
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Venture over to the W220 side of this forum. Cowboyt is having the exact same issue with his V12. Much good advice in his thread. Please report back here with your findings. Thanks!
 

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Discussion Starter #5
I did replace the spark plugs and I did get the coil pack from Clark. I think it's a vacuum line. Good suggestion for the ignition pack.. didn't know Clark did that. I might try that next. Any pictures of a V12's vacuum lines would be a great help... kinka flying blind here. Thanks for the responses.
 

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Discussion Starter #7
Took to my mechanic to straighten out the vacuum lines. He got those sorted and then was still getting misfiring error codes. Took the passenger side coil pack off.. number 4 spark plugs had oil INSIDE. Scoped the cylinder and there is oil on the piston and a scar on the cylinder wall. Cold start #4 had 140 misfires in just a few minutes... Basically it looks like this engine might be shot.

Any suggestions?
 

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Darn! That stinks!! If you love to work on cars like I do, pull the engine and do a failure analysis. If you choose to sell it, do not sell it without full disclosure. If it is in good repair otherwise, and it were mine, I would enjoy fixing it. You would certainly learn a lot along the way. ?
 

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Discussion Starter #9
Darn! That stinks!! If you love to work on cars like I do, pull the engine and do a failure analysis. If you choose to sell it, do not sell it without full disclosure. If it is in good repair otherwise, and it were mine, I would enjoy fixing it. You would certainly learn a lot along the way. ?
I didn't get full disclosure... this car was just slapped together enough to drive it onto the trailer to ship. Missing bolts, coil pack on the pass side a used one (when told it was a rebuilt one) and not even bolted up.. one bolt holding the ABC pump on after they broke a bolt off in the block... on and on... Have spent thousands trying to get to pass emissions and not drag the wheels on the fenders because of the ABC issues. Bruce Mansel (I think) sells a lot of cars on BaT and this was one...
 

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Link to the BAT auction?

Not that it helps your cause, I’m just being nosey...I’ve seen him sell some cars on there that looked like real stinkers.

sorry about your bad luck man, really sucks.
 

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I guess it depends on how much you trust your mechanics diagnosis. A guy in this thread had oil on his plugs and found it was caused by a bad pcv valve (I think it’s 275 010 02 91)

 

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Bruce Mansel (I think) sells a lot of cars on BaT and this was one...
Please forgive the sidetrack -- has Bruce helped with his MB part & service contacts? He seems like the go to guy for all things V12 Merc (or at least portrays that image on BaT).
 
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