Switch to Mech IP ?

[DA BIG ONE]

I like the DB4 and considering going to it. I've figured out how to get past the t-case (NP246 autotrac) issue by using a mech shifter, a stand alone tranny controller will work for the 4L80e, however speedo, cruse control, electronic HVAC, among other things maybe an issue, any of you know if this can be worked out using orignal harness, or?

[Bobbie Martin]

Speedo & glow plugs are no problem, HVAC shouldn't be. Cruise is easy as well. Jim will have some info real soon that will answer most of your questions. Unless you are planning really big HP, a DB2 should be all you need. They can make 300 HP. I can tell you 4X4 transmissions may not have all the sensors you need for a standalone trans computer. Sensors can be installed, but require a complete disassembly. OBDII trucks will require some different steps, but I'm sure its something that can be worked out. You keep the existing PCM, just remove certain circuits from its control and leave what you want it to control. One more thing - whatever it takes, it's well worth it. A mechanically injected 6.5 TD is the only way to go. If you ever make it up to Jacksonville, I would be happy to show you our Sub.

[DA BIG ONE]

Originally posted by Bobbie Martin:
Speedo & glow plugs are no problem, HVAC shouldn't be. Cruise is easy as well. Jim will have some info real soon that will answer most of your questions. Unless you are planning really big HP, a DB2 should be all you need. They can make 300 HP. I can tell you 4X4 transmissions may not have all the sensors you need for a standalone trans computer. Sensors can be installed, but require a complete disassembly. OBDII trucks will require some different steps, but I'm sure its something that can be worked out. You keep the existing PCM, just remove certain circuits from its control and leave what you want it to control. One more thing - whatever it takes, it's well worth it. A mechanically injected 6.5 TD is the only way to go. If you ever make it up to Jacksonville, I would be happy to show you our Sub. Thanks for the reply, I'm wondering what sensors are needed for the tranny?, guess I'll research this. I do know my tranny has no speed sensors because all 3 are on the t-case 1) for speedo, 1) for the front driveshaft, 1) for rear driveshaft.

[Bobbie Martin]

Originally posted by DA BIG ONE:
I'm wondering what sensors are needed for the tranny?, You should have a speed sensor in the front of the 4L80E (input speed) and one in the transfer case. The one you need is the rear (output) speed sensor. The hole for the sensor is in the transmission case, but most 4X4 4L80E's do not have the reluctor ring to signal the sensor and from what I am told, this requires a complete tear down to install. Actually you can use the sensor in the transfer case, if you never use low range. The PCM has provisions to compensate for the speed difference in low range but the standalone TCM's don't have this feature. I have heard that one of the aftermarket TCMs might, but I'm not sure on this. In low range, the transfer case speed sensor is turning 2.6 times faster (or whatever the low range ratio is) and the standalone TCM sees this as a massive transmission failure and will not shift. You should keep the transfer case sensor for the speedo, etc. Once you install the additional trans sensor and related wiring, a standalone TCM works fine. I have an idea that may work without the extra sensor, but I'm still looking into it.

[DA BIG ONE]

I'm thinking that it may be as simple as removing wiring from main computer that controls the DS4 only, or am I missin something here? It's just a TPS signal, and crank position the computer needs to manage tranny, t-case and everything else, or?

The DB2 or 4 have mech advance, governor, and simple 1 wire shutdown wouldn't adding the TPS be all that is needed, or do I stay with the stock pedal and modify it to also include the throttle cable too.

Since I had gone to taller tires w/my 3.42 gears (final is 3.09:1) there has been a small issue w/converter lockup, which I have found using the cruse control eliminates the lockup issue. Of course I can't use cruse control all the time, but thinking I maybe better off saving as much of what I already have and still go w/mech IP conversion.

[Bobbie Martin]

There is a bit more to it, but basically you have the right idea. Having a OBDII and 4X4 complicate it somewhat, but it shouldn't be all that hard - at times maybe frustrating & time consuming though. You could keep your existing PCM and go the modified throttle pedal with APP route, but most don't shift as well as the standalone TCM's do. I tried both ways in addition to several other experiments and could never get the modified APP method to produce satisfactory results. Others claim they have, but my guess is they get it close and just put up with the results. I could get it 90%, but finding that last 10% was the hard part. With the standalone TCM, the APP is eliminated.
I'm jumping the gun a bit, but there is a book that will be available very soon detailing everything you need to do for the conversion. Jim should be posting it any day now. It doesn't cover OBDII 4X4 autos, but it will contain all the other info you are looking for. Stay tuned!

[DA BIG ONE]

Originally posted by Bobbie Martin:
There is a bit more to it, but basically you have the right idea. Having a OBDII and 4X4 complicate it somewhat, but it shouldn't be all that hard - at times maybe frustrating & time consuming though. You could keep your existing PCM and go the modified throttle pedal with APP route, but most don't shift as well as the standalone TCM's do. I tried both ways in addition to several other experiments and could never get the modified APP method to produce satisfactory results. Others claim they have, but my guess is they get it close and just put up with the results. I could get it 90%, but finding that last 10% was the hard part. With the standalone TCM, the APP is eliminated.
I'm jumping the gun a bit, but there is a book that will be available very soon detailing everything you need to do for the conversion. Jim should be posting it any day now. It doesn't cover OBDII 4X4 autos, but it will contain all the other info you are looking for. Stay tuned! I'm sittin on the edge of my chair for the book!

As for the 4wd/ABS/Trans issues I'm diggin deep into the harness feeds and outputs for drivetrain management. The 4wd & ABS depend on the three speed sensors on my t-case I'd hate like he_l to have to get back into my big bucks tranny w/low miles just to install reluctor wheel.

I have late lockup of the converter because of my gear and tire change but found that using cruse control lowers rpms 300/400 rpms under same driving conditions, so I'm thinking some hacking maybe in order to bring lockup back to or close to normal.

How would I even time the DB IP?

[Bobbie Martin]

Originally posted by DA BIG ONE:
The 4wd & ABS depend on the three speed sensors on my t-case I'd hate like he_l to have to get back into my big bucks tranny w/low miles just to install reluctor wheel.
How would I even time the DB IP? Some rebuilt transmissions have the reluctor wheel installed. If you want to check, find the plug on the back of the transmission and look/feel for the reluctor ring. It has teeth just like a gear. You can find very good info on reluctor rings & speed sensors
HERE. (http://www.jagsthatrun.com/V8-chapters/V8-tpi-Speed-Sensors.pdf)

Timing is done with a timing meter.

[DA BIG ONE]

Originally posted by Bobbie Martin:
</font><blockquote>quote:</font><hr />Originally posted by DA BIG ONE:
The 4wd & ABS depend on the three speed sensors on my t-case I'd hate like he_l to have to get back into my big bucks tranny w/low miles just to install reluctor wheel.
How would I even time the DB IP? Some rebuilt transmissions have the reluctor wheel installed. If you want to check, find the plug on the back of the transmission and look/feel for the reluctor ring. It has teeth just like a gear. You can find very good info on reluctor rings & speed sensors
HERE. (http://www.jagsthatrun.com/V8-chapters/V8-tpi-Speed-Sensors.pdf)

Timing is done with a timing meter. </font>[/QUOTE]Man your a great help!
Thanks