All stangs hesitate and buck

[PeTr0]

I love my mustang and i wouldnt trade it for the world. Ever since i bought it i notice that it hesitates when i slam on the gas from a rolling start. I have had mechanics and dealers look at it...they all dont even notice the prob. My friends and I all do though. I have new Tbody with IAB and TPS the tps is set and i cleaned the egr. To me i think it might be a lean condition(plugs look a lil white). I dunno people told me that all mustangs do that little buck. I drive around in my friends 99 trans am and am amazed by the smooth acceleration. What can i do?

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Red 1993 Gt- flowmasters,BBK Shortie Headers, BBK Hi-Flow H-Pipe, BBK cold air induction w/K&N, Pro 5.0 shifer, 130 amp alt., underdrives,65mm T-body,MSD 6AL and blaster tfi coil pioneer cd player and kicker component speakers, Kenwood Excelon amp, 2 12" subs in the hatch,firehawk sz50 all around, timing bumped to 13 deg., ADS Superchip, and mobil 1 oil lubing the 302.
waiting to be installed: 190 lph fuel pump

[Blown95GT]

You mignt want to give Johnson Motorsports a call and try a JMS chip. He'll work with you on your problem. http://www.jmschip.com/

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Black on black '95 GT convertible, 9# Powerdyne, SVO Motorsports intake, 65mm TB, 75mm Pro-m supercharger calibration, 30# injectors, 190 FMS fuel pump, Kirban FPR, 1.7 Cobra rockers, SmartSpark, JMS chip, MAC headers, Borla cat back, FMS 'Z' trans (was AODE), Pro-50 shifter with Steeda Tri-ax handle, 3.27 gears, Kenny Brown subs, Bilstein shocks & struts, H&R race springs, Maximum Motorsports LCA’s & CC plates, K&N filter. 180 deg stat, Saleen twin gauge pod, S281 wing, ‘96 Cobra wheels.

[Capri306]

Okay I don't think IMPO that a chip is going to solve this problem. The chip could be your problem altogether. My AOD-equipped '87 with Mass Air conversion doesn't have a stumble or hesitation whatsoever. Foot to the wood = big time go on that car. What is the TPS set to? How about the throttle body; are there any mods to support it? That could be another element. Does the BBK cold air kit include a new MAF sensor? If you're using the stocker it could just be getting "slow". I've seen that before especially ones with over 100K on them. You might wanna reset the computer and idle speed by going over to corral.net and look up their tech article on resetting idle speed. There's no engine codes coming up are there (Check Engine Light)?

Hook up a vacuum gauge to the vacuum tree and get a reading at idle. By using this and knowing what to look for (it's kinda hard to describe) when observing it and playing with the throttle, you can determine if there's a vacuum leak throwing you lean. Check the operation of the MSD box (I have my doubts on those systems, just my opinion) and coil. A fuel pressure check would be the next thing after that. Hope you find the prob!

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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch

[Dark_5.0]

My car was doing the same thing as yours when I would stomp on the gas there was a hesitation or buck.

On my car it was a faulty spark plug wire that caused the problem. The wire looked fine but it wasnt just as soon as I changed out the wires problem was solved.

Hopefully it will be something as simple as that.

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88 mustang gt convertible bored to 306 BBk equal length headers mac cold air fender kit cowl hood nitto drag radials ford racing clutch flow masters h-pipe 160* thermostat 16 degrees of timing electric fan off 94' t-bird jacobs electronics cap and wires. Edelbrock 1 1/2 inch drop springs.
best 60 ft 2.14, best 1/8th 9.65, best 1/4 15.2 @89mph, Stock gears and 3000+ Altitude

[Mr 5 0]

PeTrO:

Just for the record; all 'Stangs do not buck and hesitate.
Thousands of Mustang owners will attest to that statement, including me, with 110,000 buck-free, hesitation-free miles on my '90 LX 5.0.
Besides, If that were true, who would want to buy a 5.0? They would a headache to drive.

You have a problem specific to your vehicle that, once corrected, will eliminate the bucking and hesitation you now suffer with.

Also, comparing your eight-year-old Mustang to a '99 GM car and noticing the difference is just stating the obvious. Comparing it to a '99 GT would get you the same experience, except you would be more comfortable and the GT would handle better.

I wish you success with locating your problem and getting the bucking out of your 'pony'.

[PeTr0]

All these problems were there when the car was stock. So the mods are not causing the problem. TPS is set to .98 I agree with everything you say MR. 50 I just dont know what else i can do...i need to check for vacuum leaks and for the fuel mixture.

130 amp alternator or not.....my guess (and I'm surprised noone else caught this - and, I've seen it happen before) is the problem is your underdrive pulleys. With the kickin' system you've got in that car, those pulleys aren't spinning that belt fast enough to keep that alternator juiced. I almost guarantee that this is your problem. Lose the pulleys.......or the stereo

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'90 LX 5.0; 12K original miles (no sh*&); 3.55 gears; pulleys;Edelbrock Performer Heads; BBK shorties; MSD 6AL box w/ blaster 2 coil; Motorsport E303 cam; Pro-M 75mm MAF; BBK 70mm TB; Eibach spring kit; Southside welded subs; K&N cone filter charger; Hurst shifter; fiberglass turbo hood; A/C-less; rear seat-less; cat-less; 2 chamber Flos; Corbeau racing seats (fronts);
30# injectors; JMS Chip; 190 lb fp; TFS track heat Intake (12.299 @ 113)

[Stang Runner]

Lose the stereo Not the pulleys

[blueneonman1]

My stang hesitates sometimes when its cold. I remember when i gutted my catpipe and put it back on. For about 20min of test driving, the car would hesitate then lurch when i mashed the gas. Then it was fine. That was probably the computer adjusting to the new setup. If yours is doing it often i would have it checked out cause like I said mine only does it when cold.

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Blueneonman - '95 5.0L Mustang GT Convertible | K&N Custom Cold Air Intake | FMS 9mm Wires | Hollow Cats | Flowmaster 2 Chambers | BBK Subframes | 6-pt Rollcage | King Cobra Clutch | FMS Adjustable Clutch Cable | B&M Short Throw | Coolest Neon Lighting on a Mustang EVER!

Homepage: http://www16.brinkster.com/blueneonman/

AOL IM: blueneonma

Petro.......are you listening - or can't you hear us over that kicka$$ system you have? Given your choice of losing the pulleys or system (which I'm sure you take great pride in)I'm assuming you'll be dropping the u/p's!

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'90 LX 5.0; 12K original miles (no sh*&); 3.55 gears; pulleys;Edelbrock Performer Heads; BBK shorties; MSD 6AL box w/ blaster 2 coil; Motorsport E303 cam; Pro-M 75mm MAF; BBK 70mm TB; Eibach spring kit; Southside welded subs; K&N cone filter charger; Hurst shifter; fiberglass turbo hood; A/C-less; rear seat-less; cat-less; 2 chamber Flos; Corbeau racing seats (fronts);
30# injectors; JMS Chip; 190 lb fp; TFS track heat Intake (12.299 @ 113)

[jimberg]

Spark plug wires is a good bet. 5 and 6 can cause special problems on 5.0s since they are next to each other in firing order. With at hot coil and bad wires, you can have a crossfire every now and then. You can't just look at wires, either. It's possible to accidently loosen a crimp during a tune up. Wires tend to move around on acceleration and decelleration. One could be shorting against the block only during those instances.

When's the last time you did an actual tune up? Cap, rotor, and plugs? What about a fuel filter?

You should only check plugs directly after doing a run.

Replacing the ACT, ECT and O2 sensors is probably a good idea at this point. After you replace all of the sensors, reset your computer.

You did say you had this problem before the ADS chip, right?

Oh, as for his stereo. I'm sure that he's tried turning it off when test driving. I'm pretty sure that's not it. I was actually gonna tease him about the subwoofer messing with his knock sensor, but Mustangs don't have knock sensors. So how the hell do timing gears set it off?

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351W 89 Mustang GT Convertible

[This message has been edited by jimberg (edited 06-22-2001).]

[1BAD89]

I think you need to give it some more gas! I think your trying to take off at to low rpm's, try revving it a little more. I mean if you have it at like 1000rpm or sumthin and punch it it will hesitate.

Or.......maybe someone played the old "banana in the tailpipe" trick???

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'90 LX 5.0; 12K original miles (no sh*&); 3.55 gears; pulleys;Edelbrock Performer Heads; BBK shorties; MSD 6AL box w/ blaster 2 coil; Motorsport E303 cam; Pro-M 75mm MAF; BBK 70mm TB; Eibach spring kit; Southside welded subs; K&N cone filter charger; Hurst shifter; fiberglass turbo hood; A/C-less; rear seat-less; cat-less; 2 chamber Flos; Corbeau racing seats (fronts);
30# injectors; JMS Chip; 190 lb fp; TFS track heat Intake (12.299 @ 113)

[1BAD89]

Ya that would do it too! =P

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3:55's,BBK Off-Road H-pipe,BBK jet-hot coated equal length shorty headers,BBK 70mm Throttle Body,BBK adjustable clutch quadrant,C & L 76mm Mass air meter,Cobra R's 17x9 w/ 245's,Trick Flow Intake,Flowmaster Force II exhaust system, Super Duty T5,Centerforce II Clutch,Heavy Duty Radiator,9mm Ford racing plug wires,Accel cap and Rotor

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