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Slow throttle response

Locked-up-XJ

NAXJA Forum User
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Hi, A friend of mine just bought an 89' cherokee. It ran awesome at first but a couple of days after he bought it it started to stutter when you taped the gas and it also does not down shift when you floor it. We have changed the cap,rotor,wires,plugs, cleaned the IAC, checked for vaccum leaks. When you pull the vaccum line off that goes to the MAP sensor the throttle response is perfect but when you get into the upper RPM's it starts to stutter and miss and has a rough idle, but if you plug it back in it idles perfect but has horrible stutter when you tap the throttle. Anyone have any ideas?
 
adjust your TPS, and make sure your vacuum lines are not clogged.

could also be a plugged fuel filter, or a weak fuel pump
 
Thanks, I searched for ever trying to find something. I guess i didnt do it good enough. Ill start testing some stuff and see what i come up with
 
Ok, We tested the fuel pressure and wow! It initially went to 38 but then droped to 0 within 20 sec. So...... we will be droping the tank and investigating :rof:
 
Same thing happened with mine. Bought a 400 buck 95 stock XJ. motor mount bolts on passenger side were sheared off in the block, got them out trimmed fenders threw some spacers on the front coils and got everything buttoned up this morning now she's stuttering and falls flat when I blip ty he throttle.
 
As dumb as this sounds, run some lucas high mileage fuel system cleaner through it.
My cousin got a 94 and it had a bad hesitation and some of the issues your having, I run that through it and now it runs smooth as glass
 
Have you removed the TPS? If so make sure you got it back on correctly. The little lever has to be on the right side of the shaft. If not, the butterfly shaft will not rotate the TPS.
 
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