Bucking issue...

Girls can too · 04-12-2001, 08:00 PM

Unit 5302 made me come over here and bug you with my problems.

I have a long list of mods and a longer list of things that have been done over the past couple of months to clear up this issue. This thread is only for the people who are a. Intrigued or b. Bored out of their skulls.

Basic Mods:

306
E303
TW heads
TF (Track Heat) intake
65mm TB
30# injectors (running a FMU)
255 in tank & T-Rex inline pump
New MSD Cap/Rotor/Dist/Coil/6AL Box
4" Power Pipe
Long tube headers
ProM 77mm MA calibrated for a S.C. & 30#er's
Vortech S-Trim w/10#'s

History:

The new set up was installed in Sept. I've had the problem ever since. When racing (under boost) it's fine. Pushed out almost 500 at the wheels with only 7psi. (The issues causing it to pull low boost have been solved.)

When driving it anywhere between 1500 & 2700 rmps the car will begin to buck. As if I were driving in fourth gear. Give it throttle and the buck disappears. Lay off of the throttle and, once it returns to that gray area, it begins to buck again (and not slightly). ~rubbing neck...ouch!~

The following has been checked, tried or replaced, even with only 1500 miles on the new motor:

-All of the wiring was moved into the fenders and has been double checked and securely fastened, read on a Ford scanner and seems to be working properly.

-Fuel pressure is @ 38 and vacc at 15idle/10 basic throttle

-Tried another ProM calibrated the same way (for the 30's and S.C.).

-Cleaned the idle air motor and throttle body. Drilled the hole in the throttle plate 2 drill bits larger.

-Replaced and adjusted the TPS to .999

-Replaced all wires (Taylor 409's) & MSD cap & rotor.

-Bypassed the MSD box.

-Cleared the factory computer

-Replaced the O2 sensors

-The timing is @ 10'

Geeze, the list goes on. I'm just looking for something maybe over looked. Everything else is now perfect. As I said though, there's too much to list and I can't afford to continue replacing parts that in the end are fine. So someone pleeease throw somthing at me. (A brick preferably!)

I have to get my car back to it's daily driver status soon. I've had it looked at by a Ford mechanic, numerous friends and at my job (a Ford performance shop). I am at my wits end and only have three weeks until driving south for FFW. Is there something maybe I've over looked? Some trick of the trade I've never heard of? I sure hope so!

Thanks for listening and I look forward to your suggestions!

------------------
Nicolle Douglas
Girls Can Too, Editor
The Mustang Works Magazine
1993 Mustang GT - Supercharged K.C. 306
483.6 rwhp / 472.1 torque @ 7 psi

** Thanks to everyone for your ideas! I will definitely check into the computer issue. Thinking of a PMS for it. That would help for sure.

[This message has been edited by Girlscan2 (edited 04-17-2001).]

xspeed02 · 04-12-2001, 08:05 PM

Wish I had a suggestion.

Just wanted to say that really sucks and I hope you figure it out soon. Good luck Nic.

------------------
Team Xspeed Leader/Co-Founder
1990 Black Mustang GT 5spd
Current Mods: 2 1/2 Offroad H-Pipe, Borla Cat-Back Exhaust, 91-93 5 Star Pony Wheels, K&N Filter, Free Mods, Pioneer Headunit, MB Quartz Speakers, Orion Xtreme 300 Amp, 2 JL Audio W0's, 130 Amp Alternator, 3.73's
Future Mods: Engine rebuild with Trickflow Heads, GT-40 Intake, Custom Ground Cam, and 14lb ATI Procharger!
AIM=xspeed02

JP85gt · 04-12-2001, 08:31 PM

Arrrg i had a huge fight with that for a long time and it turned out to be the crane ig system. But mine caused detnation on nitros and bucking 17-2500 on motor at 10 deg timing. Id check plug gap,Replace the factory computer *the computer by the right leg of the pass seat*. I lay money its the factory computer. The reason for me nagging about the fac computer is my friend just got his coupe togather and had the same problem and he replaced the factory computer box and it was fine. If its not a miss its something thats going to piss you off when you find it. #1 sug is replace the computer with one froma junk yard or friend #2 check plug gap i dont think itd be a burnt plug because you would feel/hear detnation under boost. God speed. Might not hurt to replace the modular peace on the side of the distrib cant think of name.

fordgasm · 04-13-2001, 12:53 PM

I had similiar driveability issues after making cam and head mods to my car. Although mine is naturally aspirated. The only way I could correct the bucking and surging was to burn a custom chip. Once that was done these problems went away and I picked up a little more HP to boot.

I did not notice the rear gear ratio you are running...but a higher ratio gear also improves the streetability just because you spend less time in that 1500-2500 range.

Not sure if I helped but there's my experience.

------------------
fordgasm
CLICK HERE to see my 87 GT

302 LX Eric · 04-13-2001, 01:55 PM

I have had (sometimes still do) bucking problems - most notably as soon as new heads (TFS TW) and cam (mild Steeda cam#19 480/480) were installed. After about 500 miles the computer (I'm assuming) started to "learn" more about the new combination of parts and started to quit the bucking problem and actuall gained mph and reduced ET's!

After installation of my future (and hopefully soon to be ordered) ProCharger, I plan to have a custom chip burned (with dyno assistance, of course) in order to alleviate some of these driveablity issues.

Nicole - do you have a custom chip?

Good luck and keep us posted.
E

------------------
1991 5.0 LX Coupe - 38,000 miles

13.17 @ 106.14 mph w/ 2.138 60'

04-13-2001, 02:22 PM

I have a friend who has a 580rwhp 96 Mustang Cobra and his car wouldn't idle (surged until it died and also did the bucking you're talking about). He got the programmable Ford Motorsports Computer and since then (after getting it professionally programmed) the problem dissappeared and the car is very drivable now. Good luck, i hope this helped some.

------------------
'84 Mustang 5.0 T5, FMS aluminum radiator & 180* thermostat, 1 5/8 shortys/2.5" duals, '88 GT tail lights and wheels, Holley 4160 4 BBL, smog pump idler, now with hi-po collapsed lifters in #3 or #4

04-13-2001, 02:25 PM

Actually i should say i'm 80% sure it's the Ford programmable computer, i think he was debating on getting another brand, but i talked to him afterwards when his car was running and didn't bother to ask him which computer he bought, but he was VERY heavily leaning toward the Ford one i believe.

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04-12-2001, 08:00 PM	#1
Girls can too Registered Member Join Date: Aug 2000 Location: Dallas, Texas Posts: 364	Bucking issue... Unit 5302 made me come over here and bug you with my problems. I have a long list of mods and a longer list of things that have been done over the past couple of months to clear up this issue. This thread is only for the people who are a. Intrigued or b. Bored out of their skulls. Basic Mods: 306 E303 TW heads TF (Track Heat) intake 65mm TB 30# injectors (running a FMU) 255 in tank & T-Rex inline pump New MSD Cap/Rotor/Dist/Coil/6AL Box 4" Power Pipe Long tube headers ProM 77mm MA calibrated for a S.C. & 30#er's Vortech S-Trim w/10#'s History: The new set up was installed in Sept. I've had the problem ever since. When racing (under boost) it's fine. Pushed out almost 500 at the wheels with only 7psi. (The issues causing it to pull low boost have been solved.) When driving it anywhere between 1500 & 2700 rmps the car will begin to buck. As if I were driving in fourth gear. Give it throttle and the buck disappears. Lay off of the throttle and, once it returns to that gray area, it begins to buck again (and not slightly). ~rubbing neck...ouch!~ The following has been checked, tried or replaced, even with only 1500 miles on the new motor: -All of the wiring was moved into the fenders and has been double checked and securely fastened, read on a Ford scanner and seems to be working properly. -Fuel pressure is @ 38 and vacc at 15idle/10 basic throttle -Tried another ProM calibrated the same way (for the 30's and S.C.). -Cleaned the idle air motor and throttle body. Drilled the hole in the throttle plate 2 drill bits larger. -Replaced and adjusted the TPS to .999 -Replaced all wires (Taylor 409's) & MSD cap & rotor. -Bypassed the MSD box. -Cleared the factory computer -Replaced the O2 sensors -The timing is @ 10' Geeze, the list goes on. I'm just looking for something maybe over looked. Everything else is now perfect. As I said though, there's too much to list and I can't afford to continue replacing parts that in the end are fine. So someone pleeease throw somthing at me. (A brick preferably!) I have to get my car back to it's daily driver status soon. I've had it looked at by a Ford mechanic, numerous friends and at my job (a Ford performance shop). I am at my wits end and only have three weeks until driving south for FFW. Is there something maybe I've over looked? Some trick of the trade I've never heard of? I sure hope so! Thanks for listening and I look forward to your suggestions! ------------------ Nicolle Douglas Girls Can Too, Editor The Mustang Works Magazine 1993 Mustang GT - Supercharged K.C. 306 483.6 rwhp / 472.1 torque @ 7 psi ** Thanks to everyone for your ideas! I will definitely check into the computer issue. Thinking of a PMS for it. That would help for sure. [This message has been edited by Girlscan2 (edited 04-17-2001).]

04-12-2001, 08:05 PM	#2
xspeed02 Registered Member Join Date: Nov 1998 Location: Kettering, Ohio Posts: 119	Wish I had a suggestion. Just wanted to say that really sucks and I hope you figure it out soon. Good luck Nic. ------------------ Team Xspeed Leader/Co-Founder 1990 Black Mustang GT 5spd Current Mods: 2 1/2 Offroad H-Pipe, Borla Cat-Back Exhaust, 91-93 5 Star Pony Wheels, K&N Filter, Free Mods, Pioneer Headunit, MB Quartz Speakers, Orion Xtreme 300 Amp, 2 JL Audio W0's, 130 Amp Alternator, 3.73's Future Mods: Engine rebuild with Trickflow Heads, GT-40 Intake, Custom Ground Cam, and 14lb ATI Procharger! AIM=xspeed02

04-12-2001, 08:31 PM	#3
JP85gt Registered Member Join Date: Feb 2000 Location: Louisville,KY Posts: 27	Arrrg i had a huge fight with that for a long time and it turned out to be the crane ig system. But mine caused detnation on nitros and bucking 17-2500 on motor at 10 deg timing. Id check plug gap,Replace the factory computer the computer by the right leg of the pass seat. I lay money its the factory computer. The reason for me nagging about the fac computer is my friend just got his coupe togather and had the same problem and he replaced the factory computer box and it was fine. If its not a miss its something thats going to piss you off when you find it. #1 sug is replace the computer with one froma junk yard or friend #2 check plug gap i dont think itd be a burnt plug because you would feel/hear detnation under boost. God speed. Might not hurt to replace the modular peace on the side of the distrib cant think of name.

04-13-2001, 12:53 PM	#4
fordgasm Registered Member Join Date: Jan 1999 Location: Clayton, North Carolina, USA Posts: 803	I had similiar driveability issues after making cam and head mods to my car. Although mine is naturally aspirated. The only way I could correct the bucking and surging was to burn a custom chip. Once that was done these problems went away and I picked up a little more HP to boot. I did not notice the rear gear ratio you are running...but a higher ratio gear also improves the streetability just because you spend less time in that 1500-2500 range. Not sure if I helped but there's my experience. ------------------ fordgasm CLICK HERE to see my 87 GT

04-13-2001, 01:55 PM	#5
302 LX Eric or '331 LX Eric' Join Date: Jan 1999 Location: Columbus, Ohio Posts: 2,142	I have had (sometimes still do) bucking problems - most notably as soon as new heads (TFS TW) and cam (mild Steeda cam#19 480/480) were installed. After about 500 miles the computer (I'm assuming) started to "learn" more about the new combination of parts and started to quit the bucking problem and actuall gained mph and reduced ET's! After installation of my future (and hopefully soon to be ordered) ProCharger, I plan to have a custom chip burned (with dyno assistance, of course) in order to alleviate some of these driveablity issues. Nicole - do you have a custom chip? Good luck and keep us posted. E ------------------ 1991 5.0 LX Coupe - 38,000 miles 13.17 @ 106.14 mph w/ 2.138 60'

04-13-2001, 02:22 PM	#6
84stangLX Guest Posts: n/a	I have a friend who has a 580rwhp 96 Mustang Cobra and his car wouldn't idle (surged until it died and also did the bucking you're talking about). He got the programmable Ford Motorsports Computer and since then (after getting it professionally programmed) the problem dissappeared and the car is very drivable now. Good luck, i hope this helped some. ------------------ '84 Mustang 5.0 T5, FMS aluminum radiator & 180* thermostat, 1 5/8 shortys/2.5" duals, '88 GT tail lights and wheels, Holley 4160 4 BBL, smog pump idler, now with hi-po collapsed lifters in #3 or #4

04-13-2001, 02:25 PM	#7
84stangLX Guest Posts: n/a	Actually i should say i'm 80% sure it's the Ford programmable computer, i think he was debating on getting another brand, but i talked to him afterwards when his car was running and didn't bother to ask him which computer he bought, but he was VERY heavily leaning toward the Ford one i believe.