Hesitation at Speed....

[Y2K_MustangVert]

Alright so about 6 months ago I changed my plugs from the factory plantinum plugs to the copper plugs. Lastnight I changed them, again with copper plugs. I got in the car this morning to get some food and the car has a nasty hesitation/jerking upon takeoff and at speed. I mean it feels like I am towing a 40 foot boat behind the stang. I know it is a misfire, but how can I go about diagnosing the exact problem? There is no SES light being thrown, but I just need some guidance because this didn't happen when I changed them the first time. If anyone can throw some helpfull information my way it would be greatly appreciated.

 

[exindust]

I had an awkward misfire once too in my old mustang ( 01 ) EVENTUALLY it will probably throw a code and you will be able to determine what cylinder it is in. Other than that... put your old plugs back in one by one until the problem goes away... then you know what cylinder its in.

 

[9646gt]

when I had bad wires mine did the same thing. Would buck something horrible but never threw the first code and the wires looked perfect. Run the motor and look at it in the pitch dark and if it's plugs you will usually see the spark where they are arching.

 

[RTRBURN]

Ive been having the same problem, ended up throwing a P305 error which is a #5 mis-fire. So I changed plugs...worked ok for about 4 days....got same error again this morning. Goin to try new coil on that cylinder.....listen to see if it sounds like you have a exhaust leak...thats what it sounds like when you have a cylinder not firing. You can go to Autozone and they will pull the code and then erase it for you once you fix the problem.

 

[TangerineGT96]

i always thought you had to run plantinum plugs in the 4.6s

 

[jasonh_86]

Plugs? You don't need no stinking plugs!

I agree with exindust, just take them out and put the other ones in until it stops.. But maybe it was a bad plug or bad wires or something