Hey guys, My 2003 Mustang GT (manual) has developed what feels like a missfire. The missfire occurs at low RPMS usually less than 3000 the engine feels like it is bogging down and there is a noticeable loss in power. The whole engine feels like it is coughing. I have taken it to the dealer for warranty repair, they say there is no CEL and no codes popping, it is developing good vacuum and has good fuel pressure. about 4 times now the car has stalled when in neutral sitting at a stop light because of this issue. I have changed all the plugs to no avail. This problem is very off and on. One day the car will drive beautifully, gobs of power and other days it will feel sickly and down on power with this missfire. This is starting to really drive me crazy! any help would be greatly appriciated.

-Blake deVries

 

Check for faulty coils...

The dealership didnt powerbalance it?

 

wow that sounds like the same issue i have. can u hear it through both of your exhaust pipes or just 1? i can only hear mine on one side

 

lol the dealer isnt about to do anything they dont have to do

Id say its either the plugs, coils, or the engine wiring harness

 

Considering I work for one, I think I'd know what they should and shouldnt do.. It if was in for a misfire, and they didnt do a powerbalance, then they suck major ***.

 

As far as the exaust goes it sounds normal, there is a more aggressive burble if i lift while the problem is happening. I think its a bad coil as well, my only problem is how to determine what coil or how many when its not throwing any codes?

Edit, does anyone have a link for purchasing a single COP for the 2v 4.6? i can only find them in sets of 8 and im not about to throw $400 bucks at a warranty problem. but if i could buy just one maybe ill play a round robin game with it.

 

is there any difference in symptoms when the engine is hot or cold?

 

good question, when the engine is cold it is more rare of a problem, and the studder/missfire tends to happen closer to idle/at idle. it has stalled once at idle due to this issue when it was cold. however more often it has issues when nice and warmed up.

 

what is powerbalancing??? sounds like when your motor heats up the coils are going to $hit.

 

yea it deff sounds like the coils. it took me a while to figure out which ones where bad so i had some coils laying around the repair shop from a f-150 and replaced my whole right side coils (looking at from front) and it solved my problem. i was very nervous cause i had just my s/c on it and come to find out the guy i had wash my car which he did a aswome job, decided to power wash my engine. but problem solved, deff see if someone had stock coils laying around for 99-04 ford vehicles with the v8. hope you find out the problem