I've been tuning GM cars and trucks for a long time. I recently sold my cammed 5 speed manual swapped 6.0 Tahoe to buy an XJ. It's not my first Jeep but it's weird being an LS tuner who doesn't own an LS motor anymore. Anyway, I got the exciting news last week that HPTuners now supports our Jeeps! I just needed to upgrade to their latest hardware. I've been needing to do this anyway. I have paid for the upgrade and sent them my old hardware which they received today. I hope to have my upgraded hardware early next week and I'll immediately begin tuning my Jeep (97 XJ 4.0 manual).

I haven't gotten to look at a 4.0 tune older than 2005 but there was a JTEC tune from a stock 5.2 for me to look at. It looks like dialing in fuel, spark and power enrichment will be simple and straight forward on these. What I am really interested in is whether or not there will be a way for me to scale for different map sensors so that I can properly tune in boost if I ever go that route.

I should have probably waited until I started tuning to start this thread but I'm so excited that I wanted to see if anyone might want to discuss it.

 

I dont see why you wont be able to scale it for a 2 bar map sensor. You can with just about every other vehicle. I dont think there is going to be much power to be found on a stock engine but being able to tune for boost is going to be awesome. I am excited to see the results! Keep us posted.

 

I just ordered a 2 bar MAP sensor. Once I have it I'll be taking a trip down to the local tuner. I will try and get the most detailed information about how to get it done that I can.

 

Excellent! Thank you!

 

This is exciting and X2 on the boost tuning. I have been reading turbo builds here and priate4x4 for a while.

 

I got my MVPI2. I hooked it up last night, pulled the tune without any problems and made a short data log with it running. Here are a couple of things I noticed... My Fuel Trims seem stuck. Even on my way to work the LTFT and STFT were the same all the way to work. They were something like -3 for STFT and 1.5 for LTFT. If they aren't moving, I'll have to do any fuel tuning with my wideband or based on the narrowband voltage but I'd rather get it trimming like it should. It was commanding Closed Loop, BTW.

Also, There was no PID for MAP that was working. There's a "Manifold vacuum" PID but it stayed at 60kpa even though the MAP Voltage seemed to be reading correctly. I'll have to make a custom PID to log MAP based on voltage. I can't understand the numbers in the tune for the MAP sensor curve. Maybe someone can help with that.

Lastly, my engine coolant temperature was stuck at 90 degrees F the whole time. I suspect my sensor is bad. I unplugged it to see if it would change and it did. It went to -40 deg and threw a CEL. Then when I plugged it back in it stayed stuck at -40. I'll try to get a sensor today and see if that fixes that.

I haven't started making changes in the tune yet. I need to be able to monitor some of these parameters before I'll feel comfortable making changes.

 

I'm making some progress on scanning but the weirdest thing is in my scanner, my coolant temp seemed to be stuck at 90 deg F so I unplugged it while the engine was running to see what would happen. The CEL came on immediately and the scanner showed -40 deg. So I plugged it back in but the scanner continued to show -40 deg. I had to unplug the battery to reset the CEL and it hasn't come back on but the scanner still says -40. The gauge is working like normal and the Jeep runs fine so maybe it's a scanner issue. Is it possible for the gauge and the ECM to have different readings from the coolant temp sensor?

 

Check the voltage output of the sensor itself with a voltmeter.

 

I'm little foggy on this in my memory, but I THINK there are two coolant temperature sensors. One sensor is on the thermostat housing, at the front of the engine. For some reason, I'm thinking of a second sensor, on the intake manifold, towards the back of the engine. If there are two, I believe one is for the gauge & the other is for the computer. I can't remember. I might be thinking of a different car...

Report back with what you find.

 

Your right. There is on on the t stat housing for the computer and one on the back of the head for the gauge.

 

The ECT readings were a scanner issue with HPTuners. They have been great at addressing issues I've run across with the software. I can now log and tune my Jeep. Now I want to do some real mods!