My car is a 2002 3.0 Automatic transmission X-Type. I thought I've give one more try to specifically define my problem before I surrender to the local high $ professional mechanics. I have driven the car some 8,000 miles since this problem first started and the symptoms have remained the same and gotten no better nor worse during that period.


The problem: The car simply goes to neutral upon rapid acceleration.
In manual shift mode, which is the most reliable mode, I can shift up through all the gears pretty well unless my base line of acceleration calls for much over 2,500 rpms. Once I'm up to speed, I can down shift in the same mode without it ever going to neutral no matter the rpms. In standard automatic drive mode if I accelerate much faster than a 2000 rpm base line the transmission will go into neutral. In either instance it will return to the active gear as soon as I lift my foot. There is no jerk in the transmission, no irregular shifting, no sounds, no grinding, no vibration; the power train just goes to neutral until you lift your foot, and when you step back on the gas it resumes it's normal travel unless you continue to try to rapidly accelerate. Once it floats to neutral it remains in neutral until you stop applying fuel and let the rpms fall back about 500 rpms. The car will achieve literally any speed you desire so long as you don't try to get there in a hurry. I cruise along at 70 mph with no problem. I do notice that this problem is not as prevalent when I first start the car in the morning and take off. I have also noticed when I'm travelling in standard automatic mode up a steep grade that it will sometimes go to neutral even though I have not depressed the gas pedal to increase power, but if I let up and re-engage the gas pedal it will pick back up and continue climbing without any further glitch.


Where we've gotten so far: I did a drain and replenish of the transmission fluid several times to get a higher degree of new fluid as per the instructions found here on the forum. I inspected the externals of the engine and transmission which are both exceptionally clean and show no sign of a leak or damage.


Suggested diagnosis have included: a bad torque converter, a hole in the transmission, bad sensors, a problem with the transmission computer, a general computer problem, or a bad electrical connection.

What I'm hoping to learn: is any suggestions of how I might test to eliminate some of the problem possibilities to better identify where the problem might be before I go in search of professional assistance. It's not that I don't trust our local mechanics, its just I don't trust our local mechanics to have the expertise to identify the problem before they've spent 30 hours of shop time looking for it. I'm sure some of you can relate. Anyhow, if someone has some tests or ways to eliminate what this problem is or isn't I'd sure love to know. And, if anyone thinks they have a real good idea of how the problem can be fixed I'd love to hear that too.

 

akejama, if you can, get your hands on a data logger/viewer for the car and have someone sit in the passenger seat as you drive the car. Have them watch the computer as it is monitoring the gear selection as the computer is wanting. That should tell you if you have a computer issue or a mechanical issue. That will eliminate a lot of possibilities and start getting you going on the right path.

 

OK Thermo, I'll see if I can find someone that can help me accomplish that little task. I suppose we'll be watching for some kind of an anomaly or will it just indicate it requested neutral when under rapid acceleration? Ok that was a stupid question. Doh, I guess if a guy has a data logger/viewer for a Jag computer in his possession he'll know what to look for. I'm beginning to feel a bit more like a Sherlock Holmes always trying to solve some new mystery with this car. So thanks again Dr. Watson for your help with this new mystery. lol Have a great day Chris thanks, Tom