Burton9104

I have a 2005 Mustang GT, about 8000 miles on it. This past weekend I ran it at the track and when i got to about 4700-5000k in third gear I noticed that a quite serious knocking/ hesitation was present. I am running 93 octane and "had" the diablo tuned program in it. I took the program out and the car is still hesitating however not AS bad... didnt know if anyone had any suggestions... ? Spark plugs? Coil pack issue? what do u think?

SpazHairlip

What other mods are present; SC, electric water pump, long tubes, etc? Is the car running hot? Did you try fresh gas, maybe you got a bad batch?

Burton9104

I have the predator tuner and the C&L intake setup. If i take the intake off and tune out it the hesitation at top end of 3rd and into 4th is still present, however not as bad. I would love to bring it to the dealer but as the service manager said.. no tech is gonna go to 5 grand. I filled the car up with 93 at 3 different locations to make sure it wasnt bad gas. Maybe coil pack...? man o man... I pulled all the plugs today cleaned them all... put it all back together... still doing it..... anyone have any hesitation problems top end like me??? suggestions???

don_w

That's a stumper... I have the C&L CAI + Predator and no problems all the way to ~6500rpm. If you don't think the dealer will help, maybe a local speed shop with a dyno? I wish I could help more... good luck.

SpazHairlip

Have you checked your inline fuel filters? What about any trouble codes or engine codes, can you read then with your tuner? You could also have some hot spots on your pistons from carbon if you've really run her hard or used octane boosters. Other then putting her on a scope and running some diagnostics or putting her on a dyno it's hard to say what it could be.

Focus on what can cause your problem, if you're getting pre-ignition, look into what causes that first.

Burton9104

Thanks everyone for your suggestions... I added some wet remover just incase any condensation is sitting in the tank as well. I know this car sat for a while before i purchased it. I am really stumped as well on this one. Even when it miss fires heavily i am not pulling codes which seems REALLY odd to me. I am going to Dez racing in Seekonk for a couple dyno runs on wed. morning. Hopefully they can give me some ansswers. I went today and purchased one.. yes one coil pack... its time to start swappin.. lol... keep hitting me up with suggestions.. at this point... i will take any.... thanks

Redfire

I dont know, could it be as simple as a bad knock sensor? Ide still ask the dealer for advice. Cant hurt. I ran the feces out of mine for the first time last weekend, and it seemed to hesitate or go flat in the first 3 gears at boo-koo rpm. Later I figured it must be activating the rev limiter. I was too busy hangin on and drivin to watch the tach!

Burton9104

Well i put all my stuff back on the car. ( Diablo and Steeda Intake w/ the C&L pipe)... took the car of the highway and let the thing hesitate... hopin the light out come on... and finally in 4th gear I got a check engine light.... Blinking for a few seconds.. on steady for like a minute... then off... I read the computer and it logged a PO300- Random cylinder misfire... I am thinkin coil pack now.... Problem is now with my diablo tune in there if i put the stock tune back in ( to go to the dealer) are the codes going to erase... hopefully not... suggestions...?

PipsBlackStang

Well if you think thats its not sparking than wouldnt the excess fuel be tearing up those O2 sensors and spitting out an O2 code??? Injectors? See what your dealership says about the random cylinder misfire.

05SonicBlue

i have about 3,300 miles on my car, and find i get some knock at high rpms at w.o.t. once in a while. i don't notice serious hesitation, though, when it happens. switching to 89octane didn't really change anything. dealer said no way they were going to verify that particular issue on public roads, etc. if you find a cure that works i'd love to hear it. thanks!