Help with Jtec ECU Tuning Base Fuel Map and Pulsewidth
I have been trying to learn how to tune my 2004 Jeep Grand Cherokee 2WD 4.0L. I upgraded to the 4-hole bosch injectors and i have been trying to tune the injectors to the proper flow but when I try to my LTFTs go +15 to +20 or -15 to -20. I am still a noob at all of this but can someone help maybe point me in the right direction i will upload my data log file and the current tune file for that log.
You should be using a stand alone wideband to tune fuel trims. Have you adjusted anything in your fueling or are those the stock fuel trims?
Also make sure you are using the beta version of the scanner. Ive had issues with the stable version on all my wj's
I'm currently working on my '04 TJ 4.0 5spd manual which is NA at 6000ft elevation. Waiting for a PLX wideband O2 to be delivered before starting to tune fuel, but I'll keep an eye on this thread and help when I have the wideband and start working on fuel. At the moment just getting started with some timing adjustment. You need to be on the beta version of the VCM suite with the JTEC Jeep if you hadn't already run into that.
To help the thread are you using a 19lb 4-hole, 24lb or larger injector?
And as Outlawfab stated, have you made changes to the stock fuel trims already? Are you NA or forced induction?
what are you guys referring to as trims?
you should both post your stock reads
and i agree, op needs a wide band...
Same engine, but different vehicles and mine is a manual. Attached is the stock read using the beta version of VCM. I did notice the min pulsewidth of the file provided is shorter than mine. Not much else was different. However My LTFT numbers on a scan are very different.
One thing I am thinking though with the new injectors. These old Jeep ECMs like a long discharge to force it to relearn changes and one of the things that does is reset the fuel trims to learn. I'm assuming the 4-hole injectors are 19lbs as that's a common recommended jeep mod though we didn't hear back. If the old injectors were worn over time the ECM would have learned that. Maybe pulling the leads off the battery for 10+ minutes to discharge and then driving for about 15 minutes would get the system to relearn. You can get a new scan after that. Just a thought.
If the injectors are 24lbs or something else, this is also probably a good starting point as you have an old scan, new scan and then can see what it does after relearning.
I got my injectors out of a 03 lincoln town car i will look at the numbers and post the specs most of that tune is stock but my fuel maps i have been changing based off my LTFT I know a WB would help however fund suck right now and im doing this based off LTFT only. I am trying to get he injectors right i did find an error in my tune with my Idle Air Adjustment. i fixed it here is the latest Tune and Log file as of this morning.
A little digging indicates if they are orange from a 4.6L, they're 19lbs like the jeep 4.0. If blue, they're 24lbs.
here is the flow rate and info on my injectors here
OK, the Jeep fuel rail in these later cars is usually 49psi which would make the fuel injector run a bit more volume. Around 27-28 lbs if I understand the calculations correctly.
Assuming the motor is otherwise stock (no change to cam, not a stroker); If this is not true, then you could cause serious damage with the recommendations below.
The stock injectors are 19lbs/hr on 49psi fuel pressure in the later 4.0s. I think if you scale down the pulsewidth table on this factor you'll get the computer back to a happier baseline. I'm just getting started, but I think you'll need to multiply the pulsewidth by 0.70 (27lbs) or .0.68. (28lbs). I'd probably stay a bit on the richer side .0.70 assuming the WJ 4.0 doesn't have a knock sensor. However, I'm just getting started and would want someone with more experience with the JTEC+ platform to confirm. In the open loop tables for EGR multiply the table by this factor.
I believe the issue you're currently running into is that those injectors are going to run WAAAY to rich and on closed loop the ECU is struggling to adjust the STFT to try to stay in closed loop just doesn't understand the injector flow is so much higher than expected on the specified pulsewidth. This in turn results in LTFT that is way out of range as well.
Last edited by GoldenGorilla; 4 Weeks Ago at 10:29 AM. Reason: clarity
that would be at one bar. what about as pressure changes?Originally Posted by GoldenGorilla
what about as voltage changes?
where is the rest of the data?
I am curently out of town and in the past few days the Jeep has got new Crank Sensor, Torque Converter, Oil Pan, Valve Torque, valve cover gasket, oil pump. been a heck of a week currently i am fighting my Crankshaft Position Sensor and the air gap between my flexplate. it seems to be hitting the flex and has a elongated bolt hole so it has about 1/4" worth of play
post something like that in the LS sub-forum they would accuse you of being Ai
just sayin
*i hope you got the valve torque that you were looking for
Last edited by LilSick; 4 Weeks Ago at 06:08 PM.
It's the valve cover torque limiting washers. It's a 4.0 thing. They've become hard to source.
cant ya get it to seal with the evil energy (china) version that are avail on amazon?
tuned by tank [email protected]
I've been very careful not to lose any but I'm sure alot have been tossed by careless mechanics and previous owners over the years. They used to be like $0.10 ea at dealers but the OE ones have run out. For such a simple bit of stamped metal on millions of engines, most aftermarket ones have a bad reputation for not fitting correctly or not holding up when torqued. It's not just the valve cover gasket seal, but rocker clearance to the CCV baffle affected. The older aluminum valve covers had the required spacing cast into them but are often and easily broken and don't separate oil as well.
Newcomer will sell you a trick cnc aluminum set of 15 for $150.
https://www.newcomerracing.com/store...Out%29..html#/
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