Guys

In the last few days my '99 XJR has been acting weird. The revs at tick over are 1000rpm instead of 500rpm. Also when I drive at any speed the revs dont stay constant even though I am applying constant gas. They vary up and down just enough to be noticeable. Today also it stalled at the lights, never did that before.

I read a thread that seemed to have similar symptoms and a new MAF sensor was recommended. Any thoughts or advice ?

Thanks in advance!

 

Well the dealer is telling me it is the torque converter. I have an extended warranty that would cover it, but the thing isn't giving an error code, so the warranty company wont cover it. The dealer says the transmission fluid is completely burnt, and says flushing and filling with new oil may fix the problem (and needs doing anyway) at a cost of $600. Other than that I have to just keep driving the thing until I get error codes.

Any comments or suggestions ? Im looking at thousands to do a new torque converter. Anyone have any experience with a rebuilt one ?

Any help really appreciated.

 

If it stalled, it should have some sort of error code. I don't want to second guess the dealer, because I'm not there and they are. However, I'm more inclined to some sort of engine management device.

 

Thanks for your input Ken.

Can you elaborate ? There is no harm in making suggestions to the dealer.

If it helps :- I would have thought a torque converter would gradually develop a fault and deteriorate? The car drove beautifully until one day when it suddenly was over revving at stationary and the revs were jumping about at low speed.

Your help is greatly appreciated.

 

Really kind of wide open. Airflow meter, throttle body, any number of sensors, fluctuation in fuel pressure, clogged cats....

 

Thanks. I am talking to the dealer in just a moment and I will be sure to ask if he has considered these things.

I will let you know what happens.

Cheers

 

I don't see how it could be the torque converter, that's a real long reach. It would never do this at tickover, if it locked up the car wouldlock up in gear. The things it would be are related to throttle control. The carprobably has traction control which has a throttle control component. You will need to get into the traction control system and the throttle motor and throttle body. There should be some codes for a failure here. It is also possible that you have developed a vacuum leak that is affecting the supercharger bypass system, causing it to cycle.

 

I really appreciate you guys making some comments. I learn so much from this board!

The dealer flushed the system through and put in new tranny oil (cost hundreds) and cleaned the throttle body. The problem has gone, drives like a dream. They tell me there were no codes at all throughout the whole episode. The old oil was very dark.

So, maybe nothing to do with the torque converter, or maybe we caught it just in time and the new oil freed it up.

I think I got off lucky so Im not complaining.

Thanks again for your help.

 

dont see it being a torque converter as well.. shud check fuel pressure. and possible throttle failure..

 

Okay, looks like you guys may have been right. Got the car back Friday, gave it a good run on Sunday and it was fine. Monday, fine. Tuesday today, and it is doing it again. If Im driving at about 35 mph, 1500 rpm, suddenly the revs drop to 1000 rpm for a few seconds, then go back again. I dont know if it will do it at a higher speed/revs I haven't tried that. I dont want to get too far from home if its going to break down!

The dealer found no codes. They changed the kick down stud and recalibrated the throttle. They noted the gearbox shift points are "long and harsh". They thought it was the torque converter clutch sticking, flushed and put in new oil. It worked for a very short time/distance.

I'll be honest, Im not likely to get involved with something this serious myself. But I would love some ideas to be able to compare with what the dealer suggests. A second opinion never did anyone any harm.

From the earlier replies I will ask them if they checked the fuel pressure and throttle body.

Any other suggestions or insights greatly appreciated.

 

I got a bit more info from the dealer today. He is saying when they had it before they checked everything imaginable. The fuel pressure is good, did a smoke test, vacuum fine. They are sure it is the torque converter.

My warranty company usually needs an error code to authorize new parts like this. The dealer is hoping the new tranny oil is starting to show signs of discoloration etc that might act as evidence the torque converter is failing. Wont know until next week.

In the meantime, if i have to buy a new one myself, does anyone have any experience of rebuilt TC's ? Any idea where I might get one and what it would cost ?

As always, any comments really appreciated.

 

One other thing. Im probably way off, but this couldn't be something as simple as battery voltage could it ? The battery came with the car, I cant vouch for its condition. Would that suit the symptoms ?

 

Driving home tonight......traction control failure, stability control failure, engine in failsafe mode.

Any thoughts ?

 

Haven't had any problems as this with my Jag, but my Durango was giving me a fit similar to this for a couple of months. The fluctuating idle and stalling led me to believe it was intake or ignition related. The air filter was dirty, but not too bad. I changed it anyway. No improvement. The spark plugs showed some signs of wear, so I changed them. Still nothing. O2 sensor was filthy. AHA, that must be it. Nope.

On a whim, I took it to Advance Auto to have the battery tested......BINGO! Runs great now with the new battery.

 

Thanks for that. I will ask the dealer if he checked my battery when he had it last week. If he didn't I can get that done.

Cheers!

 

As Gator said, it could be the battery. In my experience, ifthe carruns good and then suddenly goes into bad mode and back again, it's power or connections, not oftenbad units.I would check the battery and all the primary wiring and connections all the way to the starter motor and the engine ground strap. Don't miss anything including the firewall terminal for the positive cable. A battery on this car can start it fine and not have the reserve to run the rest of the stuff. Keep in mind that many key systems are very low voltage, they have no sense of humor for any voltage loss. Losing voltage and amperageon a main circuit that separated into subcircuits thatoperate at 1.5 voltscan bea huge percantage loss, shutting things down!

 

I was very surprised to see in the Maintenance Manual that it takes battery voltage as a sensor input when determining the correct idling speed. I assumed once the engine was running everything runs off the alternator. The sensors run off the battery then ?

I will try it and let you know.

Thanks for your input Oldmots.

 

Damn. Phoned the dealer....they checked the battery when they had the car last week. Its fine.

Its going to be the torque converter I can feel it in my bones [:'(]

 

My car is fixed. For anyone interested......it was the connector between the wiring harness and the computer. The cleaned it out (not that it was particularly dirty) and re-connected it and the problems have gone. Been ok for a week now.

So....if you haverevs varying up and down and no error codes it is something simple to try.

 

Nice of you to tell what happened, it's just as important to the system as the responses you get.Sorry we didn't hit right on the nose, but we were getting warm! The guy that has the car in front of himdoes havesome advantage.