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Need help - 2000 XJ


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I have one of the extremely rare 2000 XJs with a 4.0L engine and 5-speed. I believe mine is the only one in Connecticut, and I've been told it's one of only two in all of New England. I've had a problem since it was new, and it's getting aggravating enough that I'd like to fix it.

 

I've been driving standard transmissions for over 60 years, and I've always considered myself to be a "smooth" driver. I don't slam shifts, my clutches last forever, and my passengers don't complain that their heads are being snapped off at the neck by the way I drive. Except ... in the 2000 XJ. It's impossble to drive smoothly. Example:

 

Say I'm on a level road at 55 MPH. I come to a slight downgrade and speed increases, so I want o ease off the throttle just a bit to maintain 55 MPH. Can't do it. No matter how gently I try to ease up on the peddle, as soon as I start it's like the engine shuts off, the driveline lets out a loud clunk, and I'm slowing down. So now I need to apply juuuuust a little bit more throttle to get back up to 55 MPH. Nope -- same thing. No matter how gently I try to squeeze on the throttle, it comes in with a bang and a lurch. It's very annoying.

 

I had the dealership look at it a couple of times while it was under warranty and they couldn't find anything wrong, sio I've been living with it. But it's not right. I want to fix it.

 

I thought it might be the TPS, but the 2000 XJ FSM doesn't have any information about adjusting the TPS. They tell me how to replace it, but no mention of an adjustment. Does anyone know if it can be adjusted? If so, how?

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I've never seen an TPS adjustment procedure for any of the HOs. And all the other sensors are the same p/n's regardless of the transmission. Except for the ECU. What's the p/n on your ECU tag? Looks like it should be either 56041667AD or 56041588AA for the standard transmission, federal emission - non-Cali cars. Maybe you have the wrong one in there...

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OP, do you have a means to check the TPS signal while actuating it very slowly and check for skips/jumps on this? Does the issue only happen at a specific RPM range? A scope would do wonderfully but a meter will suffice as well...

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26 minutes ago, AZJeff said:

Dumb idea---binding of slip yoke on the output shaft?

 

My foot is on the accelerator peddle, not the slip yoke. I know what you're referring to, my late, unlamented '99 WJ had that. This it totally different.

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16 minutes ago, zomeizter said:

OP, do you have a means to check the TPS signal while actuating it very slowly and check for skips/jumps on this? Does the issue only happen at a specific RPM range? A scope would do wonderfully but a meter will suffice as well...

 

It happens at pretty much all RPM ranges.

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4 minutes ago, Ωhm said:

Two thoughts (guesses) here:

  1. loose throttle plate
  2. faulty motor mount
     

 Thanks but neither suggestion fits the symptoms. This is basically that the slightest lifting of pressure on the accelerator peddle is like shutting the engine off -- completely.

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20 hours ago, Eagle said:

Definitely not rusted away. It only has 41,000 miles on it, and has spent most of its like garaged. And this problem has been there since I drove it home from the dealership, new.

 

Okay, then what's the part number of your ECU?

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Probably not so odd. The factory really didn't want to build any 5-speed manuals in model year 2000. When I went into the dealer to order an XJ to replace the [bleep] [bleep] [bleep] '99 WJ Grand Cherokee, the factory wasn't taking any orders for 4.0L manuals, so I ordered a Classic with automatic and Selec-Trac. This was in October of 1999, and the vehicle showed up in November. That one was turned over to my wife when I married her in 2003.

 

Somewhere along about January of 2000 I was in the parts department picking up something, and the sales manager wandered through. He knew I had wanted a 5-speed, so he mentioned that the factory was accepting orders for 5-speeds. 'But I guess you don't need one now," he said. "Wrong," says I, "let's fill out an order." So we did. And then I waited ... and waited ... and waited some more ... and waited still more. Whenever I checked, the order was still sitting there but no build date had been assigned. Jim, the sales manager kept asking if I wanted to cancel the order, and I kept on saying no. So we waited ... and waited ... and waited.

 

Anf then one day around late April, if I recall correctly, he said they had a build date. It looks like they waited until the very tail end of the 2000 model run and then did a short run of all the 5-speed orders. I could look up the date, but I think mine finally arrived in June. So it wouldn't surprise me if it's a bit of a mongrel, built from whatever parts they happened to have on hand.

 

Where did you find that info? That part number doesn't show up in my parts manual.

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I thought one or two of the North-East or New England (or whatever) states used the California emissions requirements.

 

My factory five-speed ZJ does the same sort of thing. I've been attributing it to slop in the 25-year-old/165,000 mile Dana 35. That said I have no idea how long it's been doing this because I've only had it a month, and I haven't investigated it that much. 

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20 hours ago, Eagle said:

Not looking to tune anything. I'm looking to eliminate a driveability issue.

Back in my wrenching for a living days we ran into a few driveability issues that could only be resolved with a PCM reflash/tune, but some could only be done by the stealership. 

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4 hours ago, zomeizter said:

Back in my wrenching for a living days we ran into a few driveability issues that could only be resolved with a PCM reflash/tune, but some could only be done by the stealership. 

 

I discussed an ECU reflash with the dealership and they said there weren't any available.

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