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What was that?!

X

XJ Dreamin'

NAXJA Forum User
Location
Huntsville, Texas
stock '93 ODB I, 4.0L, AW4, 2WD

I was driving into work this morning, doing about 55 climbing about 5% grade when there where three short, distinct breaks in power. It felt as if someone had a line attached to the hitch and gave it three quick little tugs: just, bump - bump - bump. Then everything was fine. My immediate reaction was an expectation that I would pull over right there and start cursing, but it continued on with normal power smooth as could be.

I'm not sure if it was faults in ignition, or a slipping of the transmission, or the tourque converter unlocking intermittantly. Anyway, not much I can do while it's operating normally. I'll have to wait for whatever it is to actually fail. Any ideas in the mean time would be appreciated.

wish me luck.
 
Uphill, 3 quick bumps ? Thats usually low fuel and the fuel pump pickup is starving...I call it my 'terrain monitoring fuel indicator' since my dash one lies most of the time..
 
mine has done that twice . Always going uphill but usually just one quick break. I have even tried to make it do it but no dice. Last time I had over 3/4 of a tank of fuel. It is just like the engine was off and then running in an extemely short time period. If you ever figure it out PLEASE let me know. I just came back from a 500 mile trip and it didn't do it once...go figure
 
Fred85 said:
^lol, he's in texas............i doubt the ice

did your RPM's go up at all during these power "breaks"??
Click to expand...

We had ice back in '94. Not today, though.

I can't say about the rpm. My heep doesn't have a tach. :gonnablow
 
luvme88xj said:
three armadilo's
Click to expand...

Well, I know it wasn't three skunks :confused1
 
RichP said:
Uphill, 3 quick bumps ? Thats usually low fuel and the fuel pump pickup is starving...I call it my 'terrain monitoring fuel indicator' since my dash one lies most of the time..
Click to expand...

Filled it yesterday. It was probably over 3/4 full when the three jinks happened. Running up a slight grade at only medium speed, I was wondering if the TCU might be trying to decide whether to unlock the tourque converter. Especially if the 216,000 miles might be wearing down the AW4 a bit. Just wondering. But, this is my first EFI vehicle so I have no idea what air in the fuel line, or at least flucuations in fuel pressure would feel like.
 
Ridr said:
mine has done that twice . Always going uphill but usually just one quick break. I have even tried to make it do it but no dice. Last time I had over 3/4 of a tank of fuel. It is just like the engine was off and then running in an extemely short time period. If you ever figure it out PLEASE let me know. I just came back from a 500 mile trip and it didn't do it once...go figure
Click to expand...

I'll be sure to drop you a line :)

It's good to know that I'm not the only one, and that it does not seem to be immediately fatal.

Thanks.
 
jeepinandy said:
Maybe a short in the fuel pump wiring? Maybe a sensor problem?

good luck.
Click to expand...

My other thought is maybe a short in the coil wiring. I just spent over $200 getting the thing past inspection and that didn't even address the leaking tranny seal, the leaking wheel cylinder, the leaking valve cover gasket, the worn out shocks, my busted seat, and the incomplete stereo install.

Thanks for the luck, anyway. I'll make good use of it :thumbup:
 
The next time it happens. Take a look at your engine service light and see if it's on or blinks. I'm pretty sure you can get an intermittant non stored code on the O2 sensor.
The engine light comes on intermittantly, when the O2 sensor is getting flacky. Usually happens at low vacuum, like going up a hill at moderate RPM's or moderately accelarating onto the interstate from an on ramp.
Check for stored codes. The key methode works pretty good for O2 problems.
A flaky O2 sensor will also often affect your top end. The motor craps out well before the red line, with the throttle mostly open at cruising speed.
 
XJ Dreamin' said:
Filled it yesterday. It was probably over 3/4 full when the three jinks happened. Running up a slight grade at only medium speed, I was wondering if the TCU might be trying to decide whether to unlock the tourque converter. Especially if the 216,000 miles might be wearing down the AW4 a bit. Just wondering. But, this is my first EFI vehicle so I have no idea what air in the fuel line, or at least flucuations in fuel pressure would feel like.
Click to expand...

OK, I've had my 5 speed do it when I've been too lazy to downshift but when the gas is low it literally dies for 1-2 seconds, usually uphill and going round a corner.
 
RichP said:
Uphill, 3 quick bumps ? Thats usually low fuel and the fuel pump pickup is starving...I call it my 'terrain monitoring fuel indicator' since my dash one lies most of the time..
Click to expand...
or detonation. used to get it in my old Plymouth Scamp slant-6 all the time when I'd be going over hills.
 
I have had the "bump-bump-bump" happen on several occasions, under different circumstances. The first time was on a long curved stretch of road, going about 30 mph. The next time was a few weeks later, stopped at a traffic light. It felt like the driver behind me had his foot slip off the brake and tap my bumper 3 times. Only thing was,there was no car behind me. I have felt it just driving on a straight level road. It does not seem to matter if the gas tank is full or low.
I am thinking torque converter.....

'88 Cherokee 4.0 Auto
 
8Mud said:
The next time it happens. Take a look at your engine service light and see if it's on or blinks. I'm pretty sure you can get an intermittant non stored code on the O2 sensor.
The engine light comes on intermittantly, when the O2 sensor is getting flacky. Usually happens at low vacuum, like going up a hill at moderate RPM's or moderately accelarating onto the interstate from an on ramp.
Check for stored codes. The key methode works pretty good for O2 problems.
A flaky O2 sensor will also often affect your top end. The motor craps out well before the red line, with the throttle mostly open at cruising speed.
Click to expand...

I haven't noticed a service light - even intermittantly. Then, for all I know the bulb could be out and it's been trying to flash at me all along. I'll try keying for codes. I haven't yet 'cause it just seems like too good an opportunity to sit there feeling like a dope as I waggle the key back and forth. I'll have to hunt up the waggle sequence and the flash de-code tables. Give me a few days to get some results.
 
Wolf said:
or detonation. used to get it in my old Plymouth Scamp slant-6 all the time when I'd be going over hills.
Click to expand...

Was that a manual tranny? I remember a lot of valve clatter from the slant-6 but not detonation - at least not with an automatic. I can get some detonation chatter out of the 4.0L if I let the oil get too low, but that feels different than this bump-bump-bump.
 
scca28 said:
I have had the "bump-bump-bump" happen on several occasions, under different circumstances. The first time was on a long curved stretch of road, going about 30 mph. The next time was a few weeks later, stopped at a traffic light. It felt like the driver behind me had his foot slip off the brake and tap my bumper 3 times. Only thing was,there was no car behind me. I have felt it just driving on a straight level road. It does not seem to matter if the gas tank is full or low.
I am thinking torque converter.....

'88 Cherokee 4.0 Auto
Click to expand...

Hah. That's two votes for torque converter (or confused TCU).
 
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