Starting this thread to document what I learn using HPT while tuning the 2002 4.7 in the 4wd QC Dak. Updates will be added to post #1.

Goals:
1) 100% mpg improvement. As of now 1/1/2022 the goal is 20 mpg on the work commute, ~35 mi one way, lots of hills.
2) As much part throttle torque between 1400-2500ish rpms.

Mods (Starting): 70mm TB, Airaid intake tube, stock air box, fuel rail wrapped, (maybe fan clutch delete + 180* stat + front end mods to get CT's to 190~195*)

Mods (During): Fan clutch delete, 180* stat, bed seals, royal purple 75w-90 gear oil in the diffs (still running the flush gear oil which is 85w-90 iirc), front air dam, possibly a short belly pan to control flow under the truck.

Anyone who has experiences & wanting to share, feel free... Currently truck was getting 16.3~16.5 mpg's with the old TB & 40's for ambient temps (this is pretty consistent). With the current cold weather event here 13.3~13.5 are what I'm getting, but that is in 20* weather driving in snow & ice. 40's are returning just in time to go back to work so I should have the 70mm TB comparison done mid next week.

Attached is a stock 5.9 JTEC file pulled from HPT repository. Anyone wanting to take a look, I believe the HPT s/w is still available to download @ no cost. Need the beta version 4.4 or greater IIRC.


reference thread for content, need to compare discussion content against jtec file parameters to see if they would apply...
https://forum.hptuners.com/showthrea...ions-and-Steps

 

Lesson #1... if the read does not grab the VIN number do not attempt to write this back to back to the ECU, I recommend asking HPT to have a look at it to make sure it looks good to write. Mine did not write, even though it prompted me for the VIN, the process erased the ECU and failed to write leaving the truck down until the ECU is squared away.

 

Update: Replacement ECM installed, truck runs, VIN not programmed in yet. Did not get the expected SRS & ABS lights, I got an ABS flash with a chime on every flash.

I have a Federal Emissions truck, required an FE ECU for the year that I have. Ran me $101 shipped.

 

Wow, that's cheap.

 

And I ordered it yesterday...

Pulled the ABS fuse to be able to take it for a spin, seems OK except for the ABS. Which does not make sense to me, if I bought a "rebuilt" ECU, they claim its plug in and go. Research revealed that the pinion & tire size need to be programmed in now...? Or is that covered when the VINs match?

Started to do an HPT read and stopped at the Gathering Info step when it failed to grab the VIN. Email to HPT already and am planning to go make a bench setup to eliminate the truck from the equation.

 

ABS really shouldn't care about your tire size, or even the pinion ratio. It reads wheel speed either directly at the wheels, or, from the diff carrier, AFTER the gears have had their effect. Why the vin needs to match? I don't really know..... Same for the SRS..... all that system needs to know is, you hit something, or, something hit you, and you are decelerating at a high rate, so, blow the bags...... The system can even tell at what angle you just got hit, so it knows just which bags it needs to trigger. I fail to understand how the vin not matching effects any of that.....

I suspect it relates back to all the separate modules needing to talk to each other, and make sure they are all on the same page..... Would be interesting to talk to someone in software development at Chrysler, and see what they have to say.

 

I think the VIN match thing has to do with the PIN and SKIM more than anything. Since the truck started and ran, I'm assuming he doesn't have SKIM (odd for an 02). When I swapped V6 for V8 PCM, the DRB connects to SKIM, I put in the security PIN (from a dealer friend, only dealers have it), then the DRB copies the VIN from the SKIM to the PCM. That unlocks the security features. I has read before that ABS requires a VIN match, but I dont understand that logic.

 

2 wheel vs 4 wheel ABS, maybe?

 

Dash is fixed lol...

Before:




After:





As of now, no concerns with the lights lol, ECU will stay as is until the other ECU issue is resolved. Drove it in to work and filled it up prior, planning to do an mpg ECO drive next week to compare JTCM v DTCM that is now back in there. I will say tho that the ECU as shipped sure was gutless for the first 10~20 miles, it is starting to "wake up" some as it adapts. Plan this weekend is to go get the parts for the bench setup from JY. Added the 2 videos to post #1 for the guy who will get the ECUs when that time comes.

Yesterday I tried another "read" of the new ECU to get HPT support to check out and it could not find the VIN so I stopped & forwarded that info to hpt.

 

HPT has requested a debug meeting and appears to be concerned with 2 ecu's not being able to read a VIN. Going to try and get that done this afternoon.