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  #1  
Old September 27th, 2017, 15:23
tn_outside2003 tn_outside2003 is offline
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DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

This is sort of a re-post of the same problem I have been having for some time.
'00 XJ Sport, 4.0, AW4 tranny. Stock except for OME lift.

I commute, at 80mph, 36 miles nonstop, each way daily. Recently the jeep has been "hiccupping" for lack of a better term. It stops pulling for just a second. The cruise control is usually on, but it does it under foot-throttle as well.
It does it more when it is hot outside. In the mornings....maybe once. In the afternoon about 6 times in 36 miles.

I noticed today that during one of the "hiccups" the RPMs jumped up, like pushing in a clutch with cruise control in a manual tranny. So the engine seemed to be revving up as if it lost connection to the tranny. But only for a split second.

Yesterday afternoon it "hiccupped" and it lost all power. It just started slowing down, under no power at all. I tapped the brake to disengage the cruise and gave it gas. The engine revved up and the jeep started pulling again. It felt as if it would just keep not pulling until it stopped....but as soon as I gave it gas all was well.

What in the world is going on? I have heard Crank sensor (new, Napa/Oreilly junk), TPS (replaced, junk yard), Cam position sensor (new/Mopar), and transmission.

If ANYONE has any idea what is going on, please provide some level of detailed response, other than "it's probably your _________." I certainly appreciate the help, but a list of "It's probably your _________" with no other information is not really that helpful. I am not being rude...but desperate. I REALLY need to get this sorted out before I end up stranded on the side of I-40. Is it my TPS, and if so, what would be the symptom and how do you know? If it is my tranny, what is the symptom, what failed, and how do you know? If it is the ______________, what is the symptom and how do you know?

If I "should probably replace my ____________" please offer why and/or how/why you suggest this.

I am good at working on my jeep. I also have a good mechanic. But the XJ is not throwing ANY codes. And you have to drive it hot, at 80mph, for 20 miles or more to make it act up. And it only hiccups a couple of times. My mechanic would be able to agree that it hiccups. But without it doing this A LOT more often or throwing codes, he would not have any more idea of what is wrong than I do.

I really need help with this one. Anyone? Please?
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  #2  
Old September 27th, 2017, 16:16
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Green Mesa XJ Green Mesa XJ is offline
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DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

Sounds like the torque converter lockup might be disengaging.

In the 91-95 XJ the torque converter lock up responds to three inputs, TPS, brake switch and I think it was the transmission computer .

Our early 90s XJ did something like this once when the inlaws borrowed it so I didnít experience it first hand. They said it felt like it had no power, no one thing seemed to make it better or worse, like taking it out of gear and putting it back, cruise control vs peddle control.
I replaced the brake switch, and the TPS, never happened again. Other thing was it had gone through one hell of a rain storm and the windshield had a leak so may be in our case water was involved.

Oh I also drain the transmission and replaced it with the recommended fluid, I donít think that was an issue .
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Old September 27th, 2017, 16:25
tn_outside2003 tn_outside2003 is offline
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Re: DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

Thank you for your detailed response and experience. It is useful. I will see what other things get posted and try to sort through it.

I was actually thinking torque converter myself. But I read that the symptoms of failure were slippage and I have not had any slippage at all. None. So...hummm....

Hoping for some more input. Thanks again for your experience with this.
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Old September 27th, 2017, 16:39
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Green Mesa XJ Green Mesa XJ is offline
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DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

Torque converter may or may not be failing, Iím not too familiar with what the symptoms would be. Our trouble was it was disengaging (un locking) at hwy speed. No trouble with since replacing those two parts and itís a 300k mile jeep. I also didnít try to trouble shoot just picked up the parts and drove to where they parked the jeep. It never failed, they got to where they were going.

On the 91-95 the brake light switch sends signals to the lights, torque converter and cruise control. Not sure what changed in 1996.


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  #5  
Old September 28th, 2017, 14:36
tn_outside2003 tn_outside2003 is offline
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Re: DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

Today I was driving at 70mph and I tapped the break while holding the gas. The torque converter disengaged and the RPMs went up, just as I would expect.
When the torque converter disengaged the loss of power was gradual. When my XJ "hiccups" it is sudden, immediate, and a total loss of pulling...for a split second. It just "hiccups" then drives normal.

WTH is going on? Anyone???? Please???

Thanks.
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  #6  
Old September 28th, 2017, 16:32
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Green Mesa XJ Green Mesa XJ is offline
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DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

Is you fuel pressure testing right?
Reminded me of a carbureted car eating the fuel faster than the bowl fills. I know it not applicable here with fuel injectors.

Didnít quite seem like the transmission or transfer case slipping, still kind of leaning towards torque converter but I maybe totally wrong, hopefully someone who has had this happen can point you the right direction.



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  #7  
Old September 28th, 2017, 16:49
md21722 md21722 is offline
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Re: DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

When my TPS failed the symptoms were as follows:

1. Taking foot off gas pedal, to coast on an exit ramp, RPM's went up enough for me to notice, like 1000 RPM or something. It was like it was downshifting to decelerate.
2. On cold start, RPM spiked to 3000 RPM.
3. Engine felt like it was cutting out for a split second. It did this repeatedly on my drive home from work. However, it was for such a short amount of time I did not lose power.

When (3) was occurring on my way home from work I purchased a new TPS from the dealer. All symptoms went away and haven't come back. That was a couple of years ago.

I suppose you could test the TPS sensor when its hot. I think you need a graphing multimeter, scope, or analog meter to ensure there are no cut outs.
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Old September 28th, 2017, 17:35
tn_outside2003 tn_outside2003 is offline
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Re: DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

Thanks MD. I was thinking torque converter or TPS. $90 for an OEM TPS. I suspect that is my next move.
Thanks again.
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  #9  
Old September 28th, 2017, 19:17
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ehall ehall is offline
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Re: DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

Quote:
Originally Posted by tn_outside2003 View Post
This is sort of a re-post of the same problem I have been having for some time.
'00 XJ Sport, 4.0, AW4 tranny. Stock except for OME lift.

I commute, at 80mph, 36 miles nonstop, each way daily. Recently the jeep has been "hiccupping" for lack of a better term. It stops pulling for just a second. The cruise control is usually on, but it does it under foot-throttle as well.
It does it more when it is hot outside. In the mornings....maybe once. In the afternoon about 6 times in 36 miles.
Sounds like problems I had with one of my ignition coils. As the engine heated up the coil winding would start to separate. Eventually it just crapped out on the side of the road. Once it cooled off I was able to limp it home (misfiring the whole way)
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Old September 28th, 2017, 22:41
md21722 md21722 is offline
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Re: DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

Quote:
Originally Posted by tn_outside2003 View Post
Thanks MD. I was thinking torque converter or TPS. $90 for an OEM TPS. I suspect that is my next move.
Thanks again.
Hope that helps, let us know the final solution. The TPS is more a less a pot that wear outs over time. It seems strange that a JY TPS would have the same problem, but maybe it drove the same roads you did. TN I-40 @ 80 MPH is very, very common unless you're going through the Nashville downtown loop at rush hour. lol. I almost wonder if its not an O2 or something like that. These Jeeps switch from closed to open loop fairly often. Above 60-75% throttle they will go open loop. IF you had a scanner that did live data it would probably help. But it doesn't hurt to have a fresh good dealer TPS either. Keep the spare under the drivers seat with a spare crank and cam sensor.
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Old September 28th, 2017, 23:09
coldcdn coldcdn is offline
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Re: DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

I'd be another vote for heat fad on your coil the symptoms and conditions all fit
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  #12  
Old September 28th, 2017, 23:37
md21722 md21722 is offline
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Re: DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

2000-2001 have the coil rail. Very much different than 1999 and earlier.
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Old September 29th, 2017, 04:47
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Re: DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

OP, do you have any codes for misfire?
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Old September 29th, 2017, 14:28
tn_outside2003 tn_outside2003 is offline
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Re: DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

No codes AT ALL. Go figure. Since I have replaced my head due to misfires, I recognize what misfires feel like. This is much more sudden and more clunky. It is like EVERYTHING disengages for half of a second. The nose of the Jeep even dips for a split second. It sort of goes "clunk," stops puling just for a moment, and then proceeds as if nothing had happened.
The most significant thing I can see is that rarely happens in cool weather, but happens every couple of miles when it is hot outside and the engine is hot.

Grrrrr. I have a replacement Echlin coil rail and I still have the original OEM, which is probably not bad. I'm planning on replacing the TPS (ordered already), replacing the plugs, and putting the OEM coil rail back on. If this does not fix it.....perhaps it is the tranny. I don't think it is the torque converter disengaging, because when I tap the brake under speed and force it to disengage, the disengage is very smooth and the loss of power gradual.

What I am experiencing is like someone turning the key off and back on, under speed, for a split second. As soo as you feel the hiccup, it is back to running normal.

Thanks for the suggestions. When I figure it out I will post the solution.
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Old September 29th, 2017, 14:44
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blondejoncherokee blondejoncherokee is offline
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Re: DESPERATE! PLEASE HELP! Engine/Tranny hiccups on Interstate?

Test/ inspect /replace :
charging system - battery , cables, alternator,
Igntion system- ignition switch, coil, ignitor , inspect/replace spark plugs and wires
fuel system - fuel pump, regulator, fuel filter
ENgine management sensors that come to mind: TPS and the CPS , coolant sensor, and o2 sensor
change trans fluid and inspect fluid
clean and inspect all grounds and sensor connections
check


also, you can probably wire the TC to a switch and cut it out of the computer altogether, and see if that helps if all else fails.

I would try to test every sensor. I had a similar issue when the coolant temp sensor was going out on my MJ years back. It would start randomly dying on me sometimes, very hard to diagnose. once we finally caught it in the act, we saw the coolant sensor would ramdonly read -15* or so out of nowhere, dump a ton of fuel, flood the motor, and kill the engine.
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