4x4 Low Range

[FJR]

Question: Is there a way to edit the low range switch parameters? I am putting a 00' 5.3l LXS with a 4l60E into my 92' jeep wrangler and have changed the transfer case over to a manual one. I still have the VSS on the out put of the transfer case so i need the pcm to be able to adjust the speed for when it is low range so it will shift right. I am putting a switch on pin C2-16 to tell the pcm its in low range and the transfer case is the same gear ratio as the stock one so it should work. But I am wondering if there are any parameters at all for the low range, would like to be able to adjust the gear ratio in the pcm so when I change it in the transfercase the shift points still work right. Would work nice for the rock crawling rigs. worse comes to worse I could use the performance mode and change the shift points for low range.

[Shrek]

HPT does not have any available parameters with respect to the 4WD option.

As long as the PCM receives the input indicating 4WD has been activated - the shifts will be scaled accordingly (for the stock transfer case ratio). One caveat is if you happen to use a "car" tune (i.e. elect to run a Camaro tune) - the 4WD option is not enabled in car tunes, only in truck tunes.

[FJR]

So if I wanted to run a car tune. (i.e. a Camaro tune) I should be able to cut and paste all the parameters into the truck tune to keep the stock 4wd low working? The car tunes will work better over time as it is slowly getting built for mud drags. Thanks Shrek for the info, good to know I can't turn the option on and off.

[Shrek]

... good to know I can't turn the option on and off ...

It can be done ... just not with HPT.

[artiechubb2]

I did a similar swap in my jeep and I had to put the speed sensor before the transfer case on the trans output shaft. I used a tone ring from advanced adapters and a universal threaded speed sensor from ebay and it works great

[FJR]

I did a similar swap in my jeep and I had to put the speed sensor before the transfer case on the trans output shaft. I used a tone ring from advanced adapters and a universal threaded speed sensor from ebay and it works great

That is what i plan on doing the next time the tranny comes out. The speedo just won't be right in low range but that won't matter.

[Shrek]

Just an update ... HPT has added a lot of parameters to the P01 and P59 ... so much so, that these new parameters can go unnoticed unless you are actively checking each folder for changes.

The T-case ratio appears to be available for the 2001+ model years. The comments that accompany this parameters refer to Torque Management calculations.

The parameter is located at Engine>Torque Management>Engine>Engine Torque Model.


Still no switch in HPT to Enable / Disable 4WD (that I have noticed).

[FJR]

I have a 99 model so I don't see it there. But at lease I know I will be on the newer ones. Thanks

[gup72]

Did you ever get it to shift at the right RPM in 4-low with the VSS on the tail shaft of the TC? I have the same issue and vehicle shifts at 1/2 the RPM it does in high range. Switch is wired correctly to tell PCM it is in 4 low.

[FJR]

I had to put a toggle switch on the dash for the 4x4 low pcm wire but it does work.

[gup72]

Does it shift at the correct RPM in 4 low? I have the same setup and the switch works because it changes the shift points, but it still only shifts at 1/2 the RPM it should. I have altered the ratio for the trans case.

[FJR]

I'm not positive but I think the 4x4 low has its own shift points that can't be changed. So for mine i but a toggle for the performance shift and adjusted it to shift in the low range ratio for full adjustabilty of the shift points. I only use the low range switch for normal driving. Then the performance for racing with the low range off.

[gup72]

I will give it a try, thanks for sharing. For this weekend I'll have to run the tune where I lied and said it was 80 tooth ring.

[gup72]

After much research and experimenting here is what I have found. BTW, my VSS is after the transfer case, not after the transmission. I hope this helps those 4x4 owners out there. The 4wd low range shift points can't be edited as they are not visible. The transfer case ratio in the parameters is only used for torque calculations. It doesn't change the shift RPM at all. The shift point is set at 4,000 RPM.

Now for what you CAN do. FJR said it above. Add another toggle to activate the performance range and use those parameters to dial in the MPH to match the RPM you want to shift at. Again, this is for those that have the VSS after the transfer case.

My advice to those building a vehicle is to place the VSS after the transmission. It makes using 4 low much more like 2wd or 4hi for shift points and performance. You may still have to use the "performance parameters and add a switch to tweak the shift points lower because the vehicle will rev much faster in 4 low. The issues doing it this way are far less then after the transfer case...IMHO.

Hope this helps!

[gup72]

Well, I had another thread in the engine section and look what someone posted! I didn't research enough!

http://www.hptuners.com/forum/showth...-tune-attached

[gup72]

Problem solved thanks to all of the input and help on here. Solution on thread link above.

Thanks a bunch everyone!