It started durring normal upshifting, suddenly no trans at all. I had the preditor plugged in at the time, hoping to log, so I blamed it, or the 93 CAI tune, though it had performed flawlessly for several months prior(r17). So then I reinstalled the factory tune and everything was fine, or so I thought. Today at the strip, I lost all trans function at the begining or by second gear, on atleast every other run.Every time at the moment of heaviest demand, wham!, I'm left coasting down the track with nothing but my stick in my hand! What a pain and embarrassment. Each time, I would have to shut off the engine, once or twice, then the trans function would be restored. And each time the little man from way down at the ticket house would come out on the track and flail his arms as though the wind they generated would get me there faster. I had the preditor with me and was switching tunes and shift options with no difference. The single pass with on factory tune did not drop the trans but I believe that was probably just luck. I'm not sure I can blame the preditor. On the way home, I see the mech fault icon blaring away. Any help appreciated
Sounds like Howdee's problem is that it's going into transmission limp mode and not just that it won't shift. Howdee, you didn't change the gear ratio parameter in the predator did you? or anything really unusual with tire/wheel sizes or something like that and you didn't correct with the predator? HAL kind of expects things to jive between engine rpm, transmission output shaft speed, and the tone rings on the axles right?
No, neither, to tell the truth,I only just noticed a reference about changing the gear ratio when looking into this. Is that a new feature? It is not available on my R17
Have you tried it? Is it worthwhile? Ive been reluctant to update beyond 17 after reading a few regrets, lost power etc. But being able to raise the GR, now thats got potential. Can't quite grasp how they could manipulate fixed mechanical gearing with a compute tune though.
They can't. But if you change the gears in the rear then you would need to make the change with the Predator so your speedo would read right and (I guess) so HAL would be happy. Since that guy tried it, it looks like HAL is definitely not happy if you change it in the Predator and don't have the gears.
The speedo sensor is inside the rearend. It reads the speed from the axles, hence why you don't have to reprogram from a gear change, only tire size changes. If the sensor was in the tranny, the speedo would be all screwed up if you went from 3.55's to 4.56 gears. There are usually 2 sensors in the transmission, one monitoring RPM coming in and the other RPM going out checking a multitude of things like slippage. So I too am confused about Diablos gear change selection the speedo corrects itself
I think it's more than just the speedo. Apparently HAL does some sanity checks and if things don't jive, throws you into limp mode. So I think if HAL detects that the axle rpm is different than it should be compared to the transmission output rpm then it's limp mode time. Different gears would do that (as well as effect the speedo). Tire size will not effect the ratio between the axle and transmission output but will effect only the speedo. Not only that but you Jeep guys got more checks to worry about. I think you want to stay within 5% (or 10%?) difference in tire size between front axle and rear axle. No tractor tires on the back unless you put them on the front too:wacko:
Exactly. As I have read the few people that have changed gears without the Diablo programming for the computer have gone into immediate limp mode. Do not pass go do not roast tires...
so... we're back to why is Howdee going into limp mode? Howdee, did it ever go into limp mode with the stock tune? Did you check for the CEL codes?
