OP
97-06 Jeep Wrangler TJ ECM / PCM Tuning Options
- Thread starter Chris
- Start date
Brianj5600
TJ Expert
Little late to this thread, but does this mean that the wonky 4 speed auto tranny in the 2006 TJ can be programmed to not be horrible?
OP
Unfortunately I don't think that's the case. At least no one has confirmed it yet so I'm skeptical at best.
OP
I can't say for sure but since no one else has said anything about it I am going to say that it's not possible. If it was, someone would have confirmed it by now.
With HPT You can change upshift and downshift for points for each gear of the 42rle for the 05 and 06 model years. This is confirmed.
Brianj5600
TJ Expert
I found that getting the timing table straight makes 42rle works pretty darn good. I rarely turn off the OD and almost always is to controlling speed going down hill on and off road.
Sweet. I wonder if a properly adjusted 42rle would lend itself to a specific gear ratio.
Nothing would change with regard to the recommended axle gear ratios because the transmission gearing doesn't change. All that changes are the shift points becoming less stupid. 33s would still need 5.38 and 35s still would not be able to be geared low enough.
I can now personally confirm you can indeed tune a @Wranglerfix PCM with HP Tuners.
If you have a manual TJ, you may need to insert a jumper wire in between pins 11 and 12 on PCM connector C1, or otherwise you will only be able to read the tune, not write it. Took me many hours to figure this out.
Not the cleanest job, but it only needs to last long enough to flash the PCM.
You'll need to buy two new credits for your new PCM of course.
If you have a manual TJ, you may need to insert a jumper wire in between pins 11 and 12 on PCM connector C1, or otherwise you will only be able to read the tune, not write it. Took me many hours to figure this out.
Not the cleanest job, but it only needs to last long enough to flash the PCM.
You'll need to buy two new credits for your new PCM of course.
I have an 05 and I have an HP tuners device that I only used to install a stock tune that I no longer use.
Would you mine explaining how I could change the shifting schedule?
I go into OD too soon with OD on (otherwise I wouldn’t turn OD off).
Unfortunately, I go into third too soon when OD is off.
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Thought process wise, how did you figure out that a jumper was needed there. Super neat that you solved it.
Before the jumper, I could read but not write. After doing a lot of intense googling I found an obscure forum post from 2008 for another car that uses the NGC3 PCM about the same thing. I looked up the pinouts, and sure enough the TJ also had spots at wires 11 and 12, and only some of them had both. Added the jumper, and I was able to write an ultra basic tune (injector fuel/time adjustment) no problem.
Cured my P0172 and P0175 issues I had once I installed the Wranglerfix PCM and now get much better fuel economy. (Those issues were not a result of the Wranglerfix PCM and instead are due to aftermarket injectors.)
In the VCM editor under the "Trans" tab, go to "Shift Scheduling" to view the various shift patterns. The important ones are the "Normal" and "Hot" schedules. Each shift has a tab, ( I.E. 3-4), and clicking on it reveals a table with axis of rpm vs throttle position. It's important to note that the row axis is incorrectly labeled as "Engine RPM". Its not. It's output shaft rpm. Adding something like 200-500 rpm to the lower throttle positions will delay the 3-4 shift notably. The same principle applies to the 2-3 shift. The 4-3 downshift can also be tuned to allow a more responsive downshift from overdrive to 3rd gear instead of having to apply heavy throttle to initiate the downshift.
Brianj5600
TJ Expert
I didn't try to adjust shift points. By improving the timing table the extra torque lessened the need to make changes to shift points.
Your profile shows a Banks turbo on your Jeep. That could make it a bit more complicated since tps, rpm and map sensor relationship is skewed by the turbocharger.