Bucking '97 TJ

[LauraA]

Our '97 TJ is puzzling us, (stick shift, 4 cyl, stock except for 30 inch ATs and gas tank skid)...it bucks occasionally. The problem is extremely intermittent. It did it once on the way back from Phoenix on Thursday and then again today and it's done it on several previous occasions, although not for quite some time. It's only happened in 4th or 5th gear thus far. It doesn't seem to matter if there's a strain on the engine or not, we can be going up hill, or on level highways. At first it did it in 4th gear but now it did it in 4th and 5th. At first, we thought it might have a fuel pump problem, perhaps cutting fuel causing it to buck, but we've had the entire fuel module replaced and thought that might have solved the problem...damnit it didn't. Of course we could take it to the dealership, but the problem is so intermittent, it wouldn't misbehave while it was with them. We're concerned about going out on the backroads alone, if we can't trust it and frankly we're totally boggled at this point. It's our daily drive as well as our means of recreation.
To describe the problem as best as I can, we can be driving along and all at once it'll just buck, sometimes just once, sometimes twice, never more. It doesn't backfire or sputter. It sorta acts like something hangs up? Then, it goes along just fine as if nothing had happened.
Boggled in the boondocks :confused:
LauraA & RalphA

[SavageSun4x4]

. We're concerned about going out on the backroads alone, if we can't trust it...

we can be driving along and all at once it'll just buck, sometimes just once, sometimes twice, never more. It doesn't backfire or sputter. Then, it goes along just fine as if nothing had happened.
Boggled in the boondocks :confused:
LauraA & RalphA
How hard is the buck???

Mine [03] will do it from time to time, its more of a slight stutter and I know many others that do same. Its really nothing to worry about.

If its REALLY bucking then you might have a concern. Only you can make that call.

[LauraA]

It's not a big buck, it's more like a stutter...so far no more than two at a time and then it's ok 'til the next time which could be a month, a week...or...?

[SavageSun4x4]

It's not a big buck, it's more like a stutter...so far no more than two at a time and then it's ok 'til the next time which could be a month, a week...or...?
I have put up with mine for 4+ years. It doesn't do it very often, just every once in a while for what ever reason...just a Jeep thing I guess.

[LauraA]

Thanks Don, I guess I'm just a natural born worrier. We'll probably just leave it alone and do something about it when or if it gets worse....just hope it doesn't happen when we're out on some unnamed backroad.:eek: :)

[Allen]

My 97 did that too! It would "hiccup" every once in a while! I think it was stealing my beer!!:D

It did STALL on me once, but it restarted!

[michaelp]

My 03 does it occasionally. I just ignore it thinking if it does come apart, there will be an explanation at least.

[SavageSun4x4]

My 97 did that too! It would "hiccup" every once in a while! I think it was stealing my beer!!:D


Yea, I would say "hiccup" is a good way of putting it:)

Mine has done that since day one 4+ years ago and 55k miles later it still does it...no ryme, no reason, haven't been able to link it to time, temp or anything else.

[LauraA]

A friend mentioned to us the problem might be the "crankshaft position sensor"... any thoughts on this?

[SavageSun4x4]

A friend mentioned to us the problem might be the "crankshaft position sensor"... any thoughts on this?
Dunno I can only fall back upon my exper with my "hiccup" with a 4+ year old Jeep and 55k+ miles and still running strong.

If it is the CPS then when it goes out it goes out be it on the trail or on the city streets. And I am sure it not a question of IF it goes out, but rather when. There is also a Throttle Position Sensor another part that will sooner or later die on you and there are other sensors on there also.

I wouldn't worry about it:)

[Sedona Jeep School]

I have been working on a '97 4.0 manual 95K miles with the same problem. The only code that came up was for Cylinder 6 misfire. So we changed the rotor, cap, plugs, and wires (all due for a change). No more engine lite, but the Jeep still bucks occasionally. :confused:

The owner says that it seems to do it only when the gas is around 1/4 tank or lower, so our next foray may be to look at fuel tank issues...

[strider]

See if the Dealer has a "copilot" system. It can be hooked up and then when the problem occurs you just push a button and the system will save the last 30 seconds of the ECM program and it may help diagnose the problem.

[SavageSun4x4]

I have been working on a '97 4.0 manual 95K miles with the same problem. The only code that came up was for Cylinder 6 misfire. So we changed the rotor, cap, plugs, and wires (all due for a change). No more engine lite, but the Jeep still bucks occasionally. :confused:

The owner says that it seems to do it only when the gas is around 1/4 tank or lower, so our next foray may be to look at fuel tank issues...

Laura, if your getting codes its a whole nother can of worms.

[LauraA]

Laura, if your getting codes its a whole nother can of worms.

No code, no nuthin' 'cept a very occasional hiccup. I like your advice not to worry about it, so that's what I'm concentrating on doing ;)
Thanks everyone for your input, it's appreciated!

[Akweks]

Mine did this when the front O2 sensor was going bad. Not always a light to associate the problem with. After I replaced the O2 sensor, it never stuttered again.