Windowlicker

Test drove a very clean low mileage 95 Limited 4.0 auto at the weekend, but when you let off the gas when cruising in 2WD, the throttle seemed to shut off very abruptly, and it didn't want to coast. Had to get back on the gas to maintain momentum, even downhill.

No heat in the brakes, free-wheeled easily in neutral. Felt like a transmission issue, but fluid was OK. 4x4 functions all engaged and released smoothly.

Any ideas? Could it be the TCC or TPS gone bad?

I miss my old XJ so much, and I'd really like to buy this one, but I don't want to buy a major transmission problem.

Thanks in advance.

MurderCityXJ

I could be exposing an issue I'm currently having, but doesn't the torque converter lock up and not disengage until you hit the brakes or drop to a certain rpm?

XJlimitedx99

Mine decelerates when you let off the gas. I figured it was normal when you drive a lifted brick.

Windowlicker

Not sure to be honest, but that would make sense. It felt very different from my old XJ, which coasted happily at any speed in Drive.

The only spec difference from mine is that it has the "Power/Comfort" button, which I think disengages overdrive in Power mode, and could conceivably slow the Jeep more rapidly. But the problem was there in the default Comfort mode.

So annoying. This XJ had one (deceased) owner, just 49k miles with history to prove, zero rust in the floorpan, very clean inside, and purrs like a kitten. Almost worth buying on the assumption it will need a tranny, although the guy is asking top money for it.

MurderCityXJ

I'm 85% positive that the deceleration on release of the skinny is normal. If the cost is right, I'd jump on that.

Lake00XJ

Mine does the same thing and I assumed it was normal. Mines a 2000 and I had to put a new engine in it, and it still does it. Tranny shifts fine.

CCKen

It sounds like the IAC is slamming shut when you let off the gas. Does it idle okay? When you initially start it, does the RPM climb to about 1,000 RPM, then gradually drift down to around 750 RPM?


Pull the inlet duct off the TB and see if the throttle plate is filthy. The original owner may have never cleaned the TB/IAC.


Edit: It could be the TPS.

Larry's XJ

Considering it "probably" has 20yr old fluids in it, or maybe from lack of use.
Seeing that most think the AW4 is one of the best transmissions made, doubt it's a trans issue. Did you check rear brakes for excess heat?

With that low of miles I'd jump on it.

HEAP of JEEP

Mine does the same thing, but on mine the the torque converter will lock and unlock while coasting downhill. So the RPS will fluctuate up and down, but if I leave just the slightest pressure on the accelerator, then its coasts fine and I don't get the weird lock/unlock issue. I've always assumed its related to my TPS but it behaves the same and I've tried both an Echlin from Napa, and a Mopar right from my dealer. I've just lived with it.

Windowlicker

Thanks for the responses guys, much appreciated. To answer your questions...

This definitely isn't "normal" deceleration. I've had 2 XJs before, and they decelerated gradually when you lifted off the gas. This one feels like you've downshifted, but rpms don't rise, so I'm sure it doesn't. Not brake drag either - there was no heat at any wheel, and it rolled easily in neutral.

It does feel like the throttle slams shut, but it starts and idles normally so I don't think it's the IAC. Lack of use/old fluids could be a factor - it's done just 10k miles in the last 10 years, and the last documented service was in 2004! It's bone stock. May even have the original tires! Certainly the original exhaust.

Unfortunately it's a 4 hour round trip to the dealer, so I can't easily diagnose further. He's a dodgy geezer trading out of his front yard, so I'm not expecting any backup!

I'm leaning towards a bad TPS forgetting to tell the TCC to unlock, but I'm tempted to buy it anyway, and take a gamble that a fluid change will cure it!

Crazy 8s

It is possible that your previous XJ had bigger tires and higher overall gear ratio... When idling, that 6-700 rpm could have been enough to push your XJ forward. The new XJ probably has stock wheel diameter.

With my XJ with 32" tires on it, I can coast at 35 mph and not put any pressure on the gas...I have a bit of an idle issue right now and it idles at 1000..which means it still wants to push a bit when I have the foot off of the gas..

salad

If it was closer to you I'd suggest getting the tires in the air and seeing if there's any resistance.

Speaking of tires, they DID have air in them, right?