Good morning, I got your call about the 3.27 rear gear and how it goes into the limp mode in third gear. I get that when my EX call me on the phone, Ha

If the car is going into limp mode it is because the rpm of the transmission and numerical error between it and the axle speeds indicates a fault to the computer. You had done smaller wheels and had no error cause they were still the same ratio. The smaller ratio is possibly causing the fault and there in is the problem.

Instead of fixing the system - computer alterations - which I can not do and choose not to persue, maybe there is a way to effect the same thing for the track.. Axle speed is involved in ABS a good thing and speed monitoring. Possibly you add a switch to the transmission to open up and thus isolate the transmission speed sensor so that the car does not go into limp mode.

I did this to my YAW sensor so that I could throw the car into turns with out throttle being cut EVEN THOUGH THE T/C IS OFF. Pulling fuses involves too much body work when you slide with 3 tires locked off the track into the pole or whatever.

See if there is a better way to trick the computer or get a limited computer to see if the body control module is the only computer affected. Its going to come down to the computer or you some where in the near future when we keep tweeking the paramaters beyond the silicon mind's ability to comprehend. I just managed to live my life as an analog engineer and dont wanna get digital programming into my resume at this point. Really I should not anyway, cause my parents were married when I was born, going digital would make all that for naught.

Good luck, Ill see the manual to see if there is a buss signal that can be deleted to circumvent the limp mode protection that your rear gear is doing to ya. BTW how is the takeoff with the better gear???? I have been told that basically in drag racing no lo gear is the best gear. Must be a torque thing. Woody

 

thanks woody that gives me some different ways to look at this, yes 1 and 2 gear at wot makes the car shake, rumble, it is nice, then you go into 3 and nothing.. don't worry i will fix it. jim

 

Good for you Jim...I have been wanting to try this for sometime now...let us know your results...

 

If you knock out the CAN signal like in the yaw sensor, it'll give you a P0700 and put you in worse shape than you are now. If you knock out your N2 or N3 speed sensors inputs, you'll get the same P0700 code and still be in worse off shape. The computer is recognizing that there is an incorrect ratio in the rearend. They actually have a DTC for that.

Everyone have a great weekend.

 

today i am going to try a limited TCU in the srt6, if that does not work i'm putting my 307 rear back into the car until we can find a solution for this. disconnected all traciton control by removing all the fuses that did not work. jim

 

Wouldnt reprogramming the gear ratio with a STAR system resolve this???

 

working on that too, I am in nice warm sunny 80 degree ft lauderdale and the people that have the star system aren't in nice warm sunny florida LOL had to get that in. buy to answer your question, yes but no one has been ask to do it,, spoke to renntec (30 miles up the street) said QUOTE ,,we make so much hp we don't need to change the rear . so i can tell you we are working on getting this to work,, example install the rear speed controllers from the rear wheels to the front, then they read the same always. jim

 

So I assume nobody came up with a fix to this?

I just can't believe that a measly .20 gear ratio difference throws this car into limp mode... If that's the case, why do I not see a problem when I run my Mickey Thompsons which are 5.08% larger in diameter than stock?

 

same question i ask when i tested the rear with 255 65 16 on the rear ran on expressway , ran them for two days no problem the 16's worked out to be a 316 rear ratio and it worked, buit the 327 went limp,,, i thing the most we can go is 321, and here is why the tranny reads speed in and out 1 and 2 gear ratio read very high , 3rd is not 1 to 1 so the tcuin 3 gear sees a speed it doesn't like it thinks the car is out of control so it goes to limp mode. i may be wrong but with what i have done this is what i have come up with jim

 

I have a limited rear in the garage and had planned to make the swap. I guess you all have saved me a lot of wrench work. I'll be watching this thread. Thanks

 

blacksrt-6 one other thing the yoke on the limited is smaller you will have to switch them when we do get this figured out jim