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Discussion Starter · #1 ·
i have a 1989 mustang 5.0 and the problem i've got is it bucks/jerks very bad around 2000 rpm (worst after driving a while). bottom end is stock, trick flow heads, 1.6 rocker arms, bbk intake, 70mm throttle body, 195 lph fuel pump, msd ignition box, shorty headers, 2-1/2 inch exhaust. i've had it to a couple small shops in town but problem is never fixed - timing checked, vaccum lines checked, etc... (one shop said i needed a bigger mass air and 24 pound injectors) but it ran good
before and i beleive it's something else. i've had no luck tring to find a mustang preformace shop close by. the bucking is so bad if you were driving beside me, you could see me inside jerking back and forth with the car (embarrissing). the problem has been going on for a couple years (i don't drive the car much-it can easily sit in the garage for 2 months not started, it's a second vehicle for me) but if i can't get this problem fixed i'll get rid of it. also runs rich (some people say lean), it'll burn your eyes if you stand behind it and pops though the throttle body when cold. any help would be great!!!!!!
 

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i would say check your grounds, the TFI module on the distributor and maybe the coil too.....
 

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clean MAF sensor, check all the plugs and see what color they are, white=lean, black=rich, yellow/gold=prefect firing, fuel filter, timing at 12degrees, also unplug your msd box and see if that clears it up they have been known for problems like this
 

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I would also check that MSD box. Where is it mounted? Hope it isn't under the hood, the underhood heat kills them.
 

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I agree with the MSD box being bad. My buddy has an 89 IROC that was doing the buck around 2500 so we got rid of the box. Hasn't done it since.:scratchchin
 

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Discussion Starter · #6 ·
thanks for all the advise - just installed the msd box about 6 months ago and the problem was there before and after installation - any more help would be great
 

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thanks for all the advise - just installed the msd box about 6 months ago and the problem was there before and after installation - any more help would be great
I'm going to go a different route here....... when the bucking starts, will it go away when you push the clutch in?



Richard
 

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Discussion Starter · #8 ·
yes the bucking stops when the clutch is pushed in - i have thought it may be a transmission problem myself but i know nothing about transmissions. thinking maybe clutch cable but only does it around 2000 rpm's. please get back with me and let me know what you think. thanks
 

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yes the bucking stops when the clutch is pushed in - i have thought it may be a transmission problem myself but i know nothing about transmissions. thinking maybe clutch cable but only does it around 2000 rpm's. please get back with me and let me know what you think. thanks

o.k., so if it is in bucking mode and you push the clutch in and it stops, does it start again when you let the clutch out? Sounds an awful lot like clutch chatter. In other words, when you you engage the clutch to shift and then let the pedal out, the disc doesn't release all the way, causing it to chatter(buck). If it is doing that and you push the clutch in and then let the clutch out and it stops, I would check the clutch. Let me know.


Richard
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o.k., so if it is in bucking mode and you push the clutch in and it stops, does it start again when you let the clutch out? Sounds an awful lot like clutch chatter. In other words, when you you engage the clutch to shift and then let the pedal out, the disc doesn't release all the way, causing it to chatter(buck). If it is doing that and you push the clutch in and then let the clutch out and it stops, I would check the clutch. Let me know.


Richard
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To add to this, if you are in neutral or clutch pushed in, and hold the rpms above 2,000rpms, what happens? Does it still break up? Can you "ride" the clutch a little and it goes away?
 

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Discussion Starter · #11 ·
yes, when it starts bucking and i push the clutch in and then let the pedal back out it still bucks. if in neutral or clutch pushed in and i get the rpm's up around 2000 rpm's it does not buck.
 

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yes, when it starts bucking and i push the clutch in and then let the pedal back out it still bucks. if in neutral or clutch pushed in and i get the rpm's up around 2000 rpm's it does not buck.

How many miles do you have on the clutch? Do you smell anything funky, as in burnt rubber smell?
It may not be the clutch at all, just trying to get a handle on the symptoms.....:scratchchin

Richard
 
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