!!!!NEED HELP Pass. Cylinders Out!!!!
Thread Starter
Instructor
Joined: Jul 2008
Posts: 202
Likes: 0
From: Houston Texas
!!!!NEED HELP Pass. Cylinders Out!!!!
After leaving LMR's dyno day on sat. my 98 M6 C5 with 30k miles completely shut off on a Curve out of nowhere....i poped the clutch and it turn righ back on but run like crap. i went back to LMR and Josh scaned it and said the my #2 cylinder was dead. when i got home i checked my spark on all my coil and only the drivers side coils worked, then out of nowhere they all kicked back on. i drove it for about 15 miles and shut it of when i turned it on 5 hours later it started up with the same problem. i took it to autozone and scanned it myself and 14 codes showed. i erased them and the car ran Flawlessly for about 15 miles. then it started doing it again but.....the cylinders shut off BEFORE the check light came on. it took about half a mile for it to turn on. soooo im Stumped.......can any one point me the right way. 
Melting Slicks
Joined: Aug 2000
Posts: 2,618
Likes: 5
From: Overland Park KS
Look for exposed wires on the coil pack harness wires at the back top edge of the block. It's kinda sharp on the rear edge of the block and over time the wires can wear thru and short.
Since it's the one side only I would guess that's your problem. I would expect a loose ground would effect both sides but I've seen some weird things in my time..
Since it's the one side only I would guess that's your problem. I would expect a loose ground would effect both sides but I've seen some weird things in my time..
Safety Car
Joined: Dec 2004
Posts: 3,526
Likes: 17
From: Santa Fe TX
After you do what you said above, and you trace anything you or the ship might have touched during any recent work/dyno/etc, check the ground wires in the electrical sticky for corrosion. Also check the one on the back of the driver's side head.
Take a good look at the battery posts and cables for good solid clean connections as well. More than a few issues have come from this area.
Take a good look at the battery posts and cables for good solid clean connections as well. More than a few issues have come from this area.
Thread Starter
Instructor
Joined: Jul 2008
Posts: 202
Likes: 0
From: Houston Texas
i checked grounds and my neighbor (a master automotive electrician) even ran it threw his computer and everything was fine. then he said the something that made me think....he said "everything's fine but it has power drops every once in a while" and yes the alternator is giving out really slowly. it even stranded me once like 6 months ago and the lights dim sometimes for no reason even with the ac off. he told me whats happening is that my computer reads power signal every 3 seconds and if its low on power 3 times in a row the computer thinks it has a problem and shut down some cylinders to prevent it from messing up. so my theory is that my alternator is bad. what do y'all think???
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Tech Contributor
Joined: May 2008
Posts: 2,843
Likes: 16
From: Howell Michigan
St. Jude Donor '09-'10-'11
I really have no idea what your problem might be, but will add some food for thought. While on the dyno, keep in mind that air flow for keeping things cool isn’t there. Check wiring around or near exhaust system for burnt areas.
What were the codes that you are clearing and what ones are returning?
What were the codes that you are clearing and what ones are returning?
Safety Car
Joined: Sep 2003
Posts: 3,558
Likes: 2
From: Cape Coral FL
I submit you have an intermittent ground connection to the passenger's side coil packs. The ground wire for the coil pack is a pair of ~18 guage black wires crimped to a single eyelet and it is fastened to the rear of the passenger side head. I believe it's a 15mm bolt. It's a real bear to get at it also. It's possible the bolt is coming loose and is making poor connection causing the packs to shut down.
Thread Starter
Instructor
Joined: Jul 2008
Posts: 202
Likes: 0
From: Houston Texas
every so often my car bings and says charge system failure, and i did check under and around the exhaust to see if there where an wires burn and i didnt find any. the only code it throws out now is in the 10-pcm and its P1571. but i read that its in the computer in 97 and 98 c5s....do u think that may be the problem?
Le Mans Master
Joined: Nov 2005
Posts: 6,993
Likes: 25
I submit you have an intermittent ground connection to the passenger's side coil packs. The ground wire for the coil pack is a pair of ~18 guage black wires crimped to a single eyelet and it is fastened to the rear of the passenger side head. I believe it's a 15mm bolt. It's a real bear to get at it also. It's possible the bolt is coming loose and is making poor connection causing the packs to shut down.
GREAT PLACE TO START LOOKING!
Melting Slicks
Joined: Oct 2007
Posts: 2,464
Likes: 2
From: Cedarburg, WI
I submit you have an intermittent ground connection to the passenger's side coil packs. The ground wire for the coil pack is a pair of ~18 guage black wires crimped to a single eyelet and it is fastened to the rear of the passenger side head. I believe it's a 15mm bolt. It's a real bear to get at it also. It's possible the bolt is coming loose and is making poor connection causing the packs to shut down.
Melting Slicks
Joined: Oct 2007
Posts: 2,464
Likes: 2
From: Cedarburg, WI
Thread Starter
Instructor
Joined: Jul 2008
Posts: 202
Likes: 0
From: Houston Texas
LOL i was thinking that maybe it had a plug with a bunch of wires that were bolted behind the passengers head meaning the person riding with me.....talk about a blond moment. i know which one your talking about now. and no i didn't check that one. i will do so tomorrow morning. i installed the new alternator and drove it for about 25 miles and no problems but I'm still going to check all my grounds. and no i didn't just spend money thats the beauty of working in a auto parts store you can get things at a "special price"
Last edited by 9lives; Aug 11, 2009 at 11:14 PM.
Safety Car
Joined: Sep 2003
Posts: 3,558
Likes: 2
From: Cape Coral FL
Now that I think about it, there is a fuse that powers each coil pack. It could be possible one of the fuses is coming loose? It isn't that hard to check, but I don't have my manuals with me to find the fuse.