03 cobra running rough

mustangsvtblack

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hey everyone i have a cobra with a 6lb lower, CAI, full exhaust, and has been tuned and dynoed 450/450 at the rear wheels. Lately it has been running a little rough like its missing. it does it at 1500-2200 rpms when im just cruising in traffic. when i floor it it goes away and runs like crazy, but when just cruising it feels like a miss or slight hesitation. Any idea?

car only gets drove on weekends and has 6800 miles on it
 

mustangsvtblack

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i just replaced the sparks plugs and gapped them at 35 and it still does it also cleaned the MAF, and IAC neither looked dirty but did it anyway.

Its just really weird, when i take off it kind of stubles like a carburated engine that has carb. issues. but smooths out when i step in it a little. But when a let it com back down and keep a steady rpm it misses.
i think it does it worse now with the autolite 103s at 35 than it did with the stock motorcrafts. hopefully someone can help this is driving me nuts.
 
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PhillyCobra

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Check and make sure no vacuum lines have come loose. If they're OK, I wold check your plugs and consider switching to an NGK iridium plug (like TR6iX).
 

mustangsvtblack

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i already looked at all the vaccum lines and they are all in place and the plugs have less than 50 miles on them. It even did it before i put the new plugs in
 

SicStang03

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PhillyCobra said:
Check and make sure no vacuum lines have come loose. If they're OK, I wold check your plugs and consider switching to an NGK iridium plug (like TR6iX).

Sorry to take the thread but why do the TR6ix's cost 6 something and the regular TR^'s cost 2 something. IS it necessary:??: to get the iridium ones??
 

RedfireSVT

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SicStang03 said:
Sorry to take the thread but why do the TR6ix's cost 6 something and the regular TR^'s cost 2 something. IS it necessary:??: to get the iridium ones??

i've got regular tr6's in my car and making almost 600hp with no problems at all, $1.70 a plug. Now the iridiums last alot longer and it can be beneficial to run a colder plug.
 

DREAMCOMETRUE

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mustangsvtblack said:
hey everyone i have a cobra with a 6lb lower, CAI, full exhaust, and has been tuned and dynoed 450/450 at the rear wheels. Lately it has been running a little rough like its missing. it does it at 1500-2200 rpms when im just cruising in traffic. when i floor it it goes away and runs like crazy, but when just cruising it feels like a miss or slight hesitation. Any idea?

car only gets drove on weekends and has 6800 miles on it[/QUOTE
Mine did just the same thing 3 weeks ago when i took it for the 1st ride after buing it. It was a bad plug, just change your plug:rockon:
 

funtruck

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Could also be a Coil Pack. A friend of mine just got his car back from the Dealer. $300 bucks to change one coil pack and a new spark plug!
 

mustangsvtblack

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well heres the deal i went out and drove it for a little while and it was still doing it so i came home and took out those piece off s*** autolite 103 and put the factory 12 heat range motorcrafts back in gapped at 36 and low and behold the problem is solved. Car runs great and idles perfect.
So warning to others autolite 103 SUCK!!!!!!
 

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