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View Full Version : hesitation...backfire...fine...

maybe2fast
January 9th, 2009, 17:22
Only happens maybe once a month

I will be driving after about a minute and the truck will bogg down and with the gas pressed more and more the XJ will not accelerate. Then there is a backfire and the xj takes off like crazy because I have continued to depress the accelerator pedal. What is this?
maybe2fast
January 12th, 2009, 16:43
usually when its cold and as weird as this sounds in a turn.
j99xj
January 12th, 2009, 20:53
Mine does the exact same thing and has been doing it for over 2 years. Never found the cause, but I do have a way to fix it for free:

When the Jeep is acting like its bogging down and losing power, give the throttle a VERY quick stab to WOT (wide open throttle) then back to no throttle. And when I mean very quick, I mean short enough to keep the transmission from downshifting.

This somehow fixes the problem. If I had to guess, it resets the TPS (throttle position sensor), so our TPSs could very well be the culprit.
Talyn
January 13th, 2009, 10:44
Have either of you tested the TPS?
89xj
January 13th, 2009, 11:03
usually when its cold and as weird as this sounds in a turn.

if it happenes in a turn i would asssume it has to do with the fuel pump assembly. is it below a 1/4 tank of gas when it happens.
maybe2fast
January 14th, 2009, 03:54
last time it happened I had over a 1/4 tank but I noted it the last time it happened.

it seems only to do it when I first start it up, but not everytime. I can't test the TPS if its working perfectly...
j99xj
January 15th, 2009, 11:14
I think our TPSs are just sticking. My "floor it" method always works. If it was fuel related more throttle (more air) would just cause it to lean out and die.
maybe2fast
January 15th, 2009, 16:09
happened again today, 3/4 tank
ipkyss
January 15th, 2009, 17:22
Happened to me for 3 years, Got very slowly worse and worse untill It was almost not drivable. Normally happened when shifting from one gear to the next. Changed both o2 sensors along with new exhaust and has been gone ever sense.
JJacobs
January 15th, 2009, 21:51
Wrong forum?
maybe2fast
January 20th, 2009, 10:33
feels more like a tps problem not a o2 sensor...but I could be wrong, but no codes.
Mainer
January 21st, 2009, 09:08
That happened to me for so long in my 97 XJ. Usually it was when I was starting out in first gear. Not necessarily on a cold start but more along the lines of when I would leave a stop light or stop sign. I pulled the codes eventually and it was missing on all six. I threw Bosch O2's in it when i replaced the cat along with the rest of the exhaust and it hasn't done it since.
seanyb505
January 22nd, 2009, 07:01
Been doing it on my 97 for as long as i can remember. I just let off the throttle throw the clutch in then continue on my merry way. It didnt even go away after I put the stroker in.
jeepster_259
January 22nd, 2009, 09:23
sounds like o2 sensors to me.
maybe2fast
January 23rd, 2009, 03:49
I did the intake swap along with a new header and everything stayed the same before and after
Ronbo
January 23rd, 2009, 06:14
feels more like a tps problem not a o2 sensor...but I could be wrong, but no codes.


A bad upstream O2 sensor on my 98 caused the same problem.
gradon
January 23rd, 2009, 09:10
Can any of you with obd2 scanners monitor your tps w/ the ignition on, but engine off and report back the values?