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View Full Version : Newbie needs help and advice.


jaredscobrasvt
09-17-2007, 11:20 AM
I need a Cobra Pro on this issue.
I just acquired an 2003 Cobra, 30 miles into the trip home, it started running rough and died on side of the road 1,000 miles from home, after a phone call and some coaching it was determined that a spark plug came out. during the process of trying to diagnose the problem i was told to unhook the negative battery cable. I reinstalled the plug and checked the others finding one other loose. i put it all back together and was back on the road, but the car is running rough and seems to be misfiring on both banks. thinking maybe i had not connected the plug boots back on properly we stopped again and checked them all and put a little dielectric grease on the rubber boot to help it slide down on the plug, this did not help. Now i'm not sure what to do, this thing has a whipple charger, with many other upgrades and tuning. I was told someone with a diagnostic machine would have to reset the computer, especialy if it has an aftermarket chip and according to paper work, it probably has a super chip in it. then someone else told me not to let anyone do that because it could mess it all up. several people suggested new plugs, but i'm sure thats not it, since it was running perfect before it happed. i did check the blown out plug and it looked fine, no cracks or anything, i did replace the coil on that cylinder because the boot was split.

looking forward to being a SVTCOBRA CLUB member, i know you guys share a wealth of knowledge.

Thanks, Jeff and Jared

blueblazes
09-17-2007, 12:28 PM
things
a. when you disconnect the battery what your doing is resetting the adaptive learning the computer has done, this pertains to short term fuel trims and part throttle driving.

b. this will in no way affect the tune that is on a chip. the chip is a basically like a flash drive where it stores its on tune and doesnt get changed except by someone with the software to tune it.

c. I would go ahead and replace the plugs just to be on the safe side. NGK tr-6 gapped between .029-.035 depending upon the amount of the boost. If you are running 17#'s then gap them at .035 if your running more then pull the gap down accordingly.

d. I would check the threads in the cylinder where the spark plug came out. This is a known issue with the spark plug threads coming out and actually blowing spark plugs out of the cylinder head.

e. if you have a friend with an xcal2 have them plug it up and check for trouble codes. Where are you located? Maybe someone on here locally can help you out some to.

f. if you have some codes post those up and that will help troubleshoot it.

g. if its misfiring on both banks you could have some bad 02's as well. bad 02's can give you issues when driving part throttle/cruising.

h. check for vaccum leaks. Easiest way is to use some starter fluid/ carb cleaner soon as you spray it near a vaccum leak the motor will react. Start there and let us know how that works.

Brandon

red04svtcobra
09-17-2007, 03:03 PM
things
a. when you disconnect the battery what your doing is resetting the adaptive learning the computer has done, this pertains to short term fuel trims and part throttle driving.

b. this will in no way affect the tune that is on a chip. the chip is a basically like a flash drive where it stores its on tune and doesnt get changed except by someone with the software to tune it.

c. I would go ahead and replace the plugs just to be on the safe side. NGK tr-6 gapped between .029-.035 depending upon the amount of the boost. If you are running 17#'s then gap them at .035 if your running more then pull the gap down accordingly.

d. I would check the threads in the cylinder where the spark plug came out. This is a known issue with the spark plug threads coming out and actually blowing spark plugs out of the cylinder head.

e. if you have a friend with an xcal2 have them plug it up and check for trouble codes. Where are you located? Maybe someone on here locally can help you out some to.

f. if you have some codes post those up and that will help troubleshoot it.

g. if its misfiring on both banks you could have some bad 02's as well. bad 02's can give you issues when driving part throttle/cruising.

h. check for vaccum leaks. Easiest way is to use some starter fluid/ carb cleaner soon as you spray it near a vaccum leak the motor will react. Start there and let us know how that works.

BrandonVery good Brandon. Also, you may have a feeling of a miss like I do in my car because if the tuner advanced the timing at idle it will feel kinda rough. Also just because you cannot see a crack in the porcelin on the plugs doesn't mean it doesn't have one, so I would change them all out as Brandon said. You also said one of the boots was split, maybe there is a nother one?? How this helps some
Chris

jaredscobrasvt
09-18-2007, 12:38 AM
sometimes its the simpler things in life that freaks us out, installed new plugs and car runs fine.

Thanks for the info.

Jeff Grant

blueblazes
09-18-2007, 09:31 AM
sweet

mrpork
09-18-2007, 08:10 PM
where are you from what state sometimes its the simpler things in life that freaks us out, installed new plugs and car runs fine.

Thanks for the info.

Jeff Grant