99 GT buck/hesitation/bump during accel?!?

warrior86

New Member
Apr 19, 2005
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Hey guys, im new to this forum.
I recently purchased a 99 mustang gt 5 spd with 28k miles in mint condition. After two days of having it, the clutch went (the mother drove it sometimes). I really didnt do much driving with it before than. We put a new clutch in (ford king cobra) and i waited to get on it.

I notice that whenever the engine is at semi low rpms and i give it gas, there is a slight bumpyness/rumble in the acceleration and i even feel it in the shifter. This happens whether im starting from a stop in first ...or in fifth on the highway. And YES, i know how to drive. Im new to mustang, is it just how they are when they try to pull at low rpm's? I have a Hurst short throw shifter in there too if that means anything.

I would say it is the clutch, but this seems to happen after the clutch is engaged. Let me give a scenario....

Say im in stop and go traffic... i am at a stop and want to get going a lil bit. I put it in first and let the clutch up while giving it gas (obviously) and i feel the clutch completely grab. Now lets say i stay at the speed it grabbed at and just eek forward. Mind you im still completely in gear and at 1500 rpm lets say. IF i hit the gas to accelerate...it WONT be smooth. There will be like little bumps that i feel in the acceleration and in my hand touching the shifter. Same thing could happen if im cruising at 60 is fifth at about 1500 to 2000 or even higher and give it gas. ALMOST.....ALMOST as if traction control is activating...but it cant be because i have it off and this car is nowhere near outta control! Any tips? My friend who knows mustangs pretty well wasnt sure either. His only guess was that maybe the mounts were loose??? Thanks for any help as i really love my mustang and want to correct any possible problems before they do damage. thanks

btw, i ONLY notice this when the car is IN gear. If i just rev it in neutral or with the clutch in everything is fine. The new clutch has 700 miles on it. We DIDNT get teh flywheel cut due to a lack of time, but we smoothed it out really well.
 
I'm having a similar sort of problem. Whenever my clutch is engaged and im in the lower rpm's, i floor the throttle and a get a "Bah-Bah-Bah" sound from the rear end, almost a sort of banging sound. However for me this problem only happens in first gear.

I haven't had the fuel filter changed since i've owned my car either ('97 w/ 70,000kms, owned since 36,000kms). What about the fuel filter not being changed would cause such a sound though?
 
Well, if its normal, then i really dont mind. THe thing that concerns me is that it DOESNT happen to my friend's 96 GT and it has the same clutch and his has 70k miles. I really doent think its normal...something is up. No i havent changed fuel filter i was planning on doing it this weekend. You think that could possibly be the culprit?
 
ok well it turns out my problem isnt fixed. It became bad again. It set off a code (finally) and it was "misfire in cylinder 1". We changed the plug and that didnt work. I swopped injectors with my friends 96 gt and that didnt work. Blew 130 bucks on a coil hoping it would work and that didnt work. What else could it be?!?!?!??!!??!?!?!??! This is so frustrating. Plus add the fact, that it doesnt do it when the car sits overnight until i drive it for like 20 minutes. ANy help would be GREATLY APPRECIATED. thanks
 
try the IAT SENSOR... this will be found on the intake tube after the mass air meter, before the throttle body.


this is known to cause bumpy accelerations...etc.


try it and get back to me.

as mentioned above:
passenger side is cylinders 1-4
driver side is 5-8




goodluck.
 
It could be because the 95 and up Mustang clutches grab really late compared to previous years. I know that import clutches (my sister has a 5spd civic) grab really close to the floor, and my Mustang clutch grabs an inch or so from the depressed position.
 
yes, thanks for the heads up but i was looking at the right cylinder. I had to think about it for a minute, but i had it right. Yeah, my cluch does grab pretty high up but it grabs completely. I really dont think its the clutch, i think its engine related. Like i said, it had the code, "misfire in cylinder 1". I will check IAT sensor and get back to you guys tomorrow. thanks for the help.
 
I have 02 GT have same problem with Traction off, I'll be getting on highway, in 4th gear serious hesitation/bucking. A week later again accelerating into 5th onto highway, even stronger bucking but as I let off gas during, it stopped, and then drove ok.

I spoke to my mechanic about being something to do with fuel injection, filter, and all fuel components. He mentioned coil also, but I'm not sure about that.

I'm going to have him disengage the the Traction control ( Ford really did this one backwards, we should have the option to turn on not off every ime we turn the key)I had tune up done last summer.
Plugs should all be ok.

I did recently have racing gears taken out, replaced with factory gears, could problem be related?
Gears installed were taken out of a MUSTANG that owner was replacing with racing upgrade.
I've been driving with these gears for about 2 months and they've been fine.

If anyone can help out with this, especially if you've had problem and found the "fix" please let me know. I love my lazor red baby!
 
I have 02 GT have same problem with Traction off, I'll be getting on highway, in 4th gear serious hesitation/bucking. A week later again accelerating into 5th onto highway, even stronger bucking but as I let off gas during, it stopped, and then drove ok.

I spoke to my mechanic about being something to do with fuel injection, filter, and all fuel components. He mentioned coil also, but I'm not sure about that.

I'm going to have him disengage the the Traction control ( Ford really did this one backwards, we should have the option to turn on not off every ime we turn the key)I had tune up done last summer.
Plugs should all be ok.

I did recently have racing gears taken out, replaced with factory gears, could problem be related?
Gears installed were taken out of a MUSTANG that owner was replacing with racing upgrade.
I've been driving with these gears for about 2 months and they've been fine.

If anyone can help out with this, especially if you've had problem and found the "fix" please let me know. I love my lazor red baby!

Its better to start a new thread of your own rather than resurrecting an old one, good luck with your problem.