Jeep tuning master thread

[tom-hptuner]

Hello I am Tom an experienced Tuner and Jeep enthusiest !

I have been messing with my HP TUNER MVPI 2 PRO and want to start a thread on how to tune 4.0 engines.

#1 before starting tuning a radical change - switch to 93 octane for safety against pinging - final tune switch back to 87 if desired for $ saving and datalog more and adjust for 87

#2 what you put into the base map is not what will happen ! other parameter move and scale the base map so go slow ! - it may say 17 degrees timing but have x1.5 somewhere you have to datalog and watch it !

My finding with MVPI 2 =
- We can now adjust transmission protocols by adjust the shifting triggers from the PCM so that overdrive downshifts to 3 sooner for those hills and highway driving (previously you needed almost WOT)
- We can adjust the torque converter lockup parameters and make life more enjoyable on the highway
- My stock tune was pretty messy im sure yours was too, the best thing to do is smooth the ignition curve out and ad more from idle to WOT through 3500 RPM's = still testing
- when changing any table be aware ignition and fuel timing have multipliers and we cant just change the EGR off base map


My tuning experience comes mainly from Carburators and to tune my jeep I started that way and turned my PCM into an emulator to act like a carburator which gave me a great basemap to tune in for my Large upgraded camshaft, low vacuum added so much fuel so it needed to lean out considerably, next i datalogged with wideband and adjusted from there then smoothed out the 3D map with my mouse, datalog - repeat I have much more work to do

(caution multipliers make this tricky and cant trust base map must datalog !)
0 to 2000 rpm 14.7 to 1 2 to 4000 rpm 13.5 to 1 4000 to 5400 11.5 to 1 and set shift point to 5400 rpm because big camshaft. - soon to be 14.7 to1 then 13.5 to 1 then 13 to 1 i am dialing it in slowly as im playing with timing at 34 degrees max now (reduced to 30 to be safe) - tune timing fatt then lean out and watch plugs and pinging sounds. (wish i had a standalone knock sensor $$$ to tell me when to stop adding timing )

after my tune is done at 25 degree F Ill wait for summer time then datalog and adjust intake air multiplier to match - no other way to test only guess.

[99-experimental-jeep]

Thanks Tom, Thanks for starting this thread. Going to be tuning our 4.0/4.6 stroker this spring once the build is done. It's also 25 degrees here in Rochester, up from 14 this morning. Where are you working from that it's 25 out? - RZ

[Skshemi]

Hello I am Tom an experienced Tuner and Jeep enthusiest !

I have been messing with my HP TUNER MVPI 2 PRO and want to start a thread on how to tune 4.0 engines.

My finding =
- We can now adjust transmission protocols by adjust the shifting triggers from the PCM so that overdrive downshifts to 3 sooner for those hills and highway driving (previously you needed almost WOT)
- We can adjust the torque converter lockup parameters and make life more enjoyable on the highway
- My stock tune was pretty messy im sure yours was too, the best thing to do is smooth the ignition curve out and ad more from idle to WOT through 3500 RPM's = still testing
- I am a big fan of DFCO and now my XJ coasts better down the HWY and gets better gas mileage, When it triggers my motor is silent its kinda cool
- when changing any table be aware ignition and fuel timing have multipliers and we cant just change the EGR off base map


My tuning experience comes mainly from Carburators and to tune my jeep I started that way and turned my PCM into an emulator to act like a carburator which gave me a great basemap to tune in for my Large upgraded camshaft, low vacuum added so much fuel so it needed to lean out considerably, next i datalogged with wideband and adjusted from there then smoothed out the 3D map with my mouse, datalog - repeat I have much more work to do

0 to 2000 rpm 14.7 to 1 2 to 4000 rpm 13.5 to 1 4000 to 5400 11.5 to 1 and set shift point to 5400 rpm. - soon to be 14.7 to1 then 13.5 to 1 then 13 to 1 i am dialing it in slowly as im playing with timing at 34 degrees max now - tune timing fatt then lean out and watch plugs and pinging sounds. (wish i had a standalone knock sensor $$$ to tell me when to stop adding timing )

after my tune is done at 25 degree F Ill wait for summer time then datalog and adjust intake air multiplier to match - no other way to test only guess.

Subbing to this!

[Jeeperscreepin96]

Hey guys! New to the site... I'm looking for a stock baseline file for a 4.0... I need one because I failed to pull one before rebuilding the motor... any help would be great!

[Skshemi]

Hey guys! New to the site... I'm looking for a stock baseline file for a 4.0... I need one because I failed to pull one before rebuilding the motor... any help would be great!

1997 4.0 Cherokee Stock Tune.hpt

[Geeknahalf]

Hi All,

New member here, hopefully you folks can help me out.
I recently built a 4.6 stroker for my 2004 wrangler and im having all kinds of difficulties with getting it to run right. The replaced parts list is quite expansive and included new cats, coil pack, cam sensor w/sync, crank sensor, wiring harness check, new throttle body sensor, throttle body, plugs, and a host of others I cant remember at the moment.

First, I dont have the tuner software yet, however im working on that... I do have a scanner that lets me read live data, so thats what ive been doing.

My issue is that all of my stft and ltft numbers are constantly in the neg. The ltft are usually in the 10+% or higher and the the stft range between -3 to -8+. I opted for the 24# injectors when I bought the kit, but Im thinking they're to big. Im looking at replacing them with stock injectors to see if that helps.

Whats a good operating range for both stft and ltft?

Also, if I get on it, it will throw a misfire code in a random cylinder and go into limp mode, throw a tps high volt code, or both. I notice that when it does this, the fuel goes into open mode and timing is stuck at 27 degrees with all other numbers reading 0. I have to pull over, shut down, clear the code and then I can drive as normal as long as I go easy on the gas.

I suspect if the fuel is too rich it would cause this as the spark is a dual fire, meaning it fires on multiple cylinders at the same time. (waste spark?)

Any help would be greatly appreciated!

R

[PSYKOSTEVO]

Without being tuned for the larger injectors AND the increased cylinder displacement, it's not a big surprise you are having those issues.

[jimmyZJ]

Whats a good operating range for both stft and ltft?
-They are supposed to ba around 0% +/-5%
But when you use E85 LTFT can reach +20% for exemple in closed loop operation, then when it goes into PE, LTFT stays ate +20%
On the other side, if you running rich with -20% LTFT, then in PE mode LTFT are at 0%, not -20% with is not the same as when they are positif
You would need hptuner to adjust your fuel table but the new device is not compatible yet
What are your fuel trim ?

[tom-hptuner]

FYI you need an older HPtuner 2+ to tune jeep engines

the LTFT is telling you what PCM is doing to make 14.7 AFR only time you see actual tune is when your in open loop at part throttle to WOT and above Closed loop threshold RPM.

the entire engine is customizable minus target AFR in closed loop

the fuel tables and ignition tables are adjustable along with transients and power adders and multipliers for WOT

target AFR should be the focus force open loop by changing O2 activation ECT to 300degrees forcing open loop constant and tune from there - when done put o2 activation back to -40 degrees f then flash then remove battery cables over night to clear closed loop data from PCM otherwise it will hurt engine by going to previous file of -20 or +20 LTFT

targets should be 13.5 to 4 AFR through 80 of power band and 12.5 to 13 AFR through 80 to WOT at Max RPM

remember tune 1 thing at a time and go slow, changing ignition timing affects AFR - more timing = richer (because it runs more efficient and uses less fuel)

what I do is open loop tune for AFR then add timing while data logging - watch tables and see what timing is actually because the tables are affected by multipliers (you can turn these off and have more of a distributor affect) or keep em and just go up slowly in each box

I keep original timing and shoot for 27 to 32 degrees timing after 2500 rpms like and old school chevy (stock pcm runs very low timing at WOT 20 or so degrees ) up it to 32 and the 4.0 HO screws !

check for pinging while going uphill WOT and watch plugs

[tom-hptuner]

Sorry ive been away guys lots of trouble with jeep but im back and tuning and ill share findings here to support everyone

I have tested alot of the PCM value and can tell you what and how to adjust to get desired affects

egr off open loop map table is used for fuel and ignition timing tables these tables are affected by multipliers from WOT - TPS - BARO - POWER - ADDERS - IAT - WARM UP - OVER HEATING tables

CAUTION all of the tables are very whacky and Chrysler programmers used bandaids in original tune but it worked and we are stuck with what looks like a real bad tune but its how they got emmissions and adaptability into the tune for weather and altitude so leave them in there and tune the base tables slowly because each box may get a different multiplier that makes no sense

1 degree of timing may be actually2 degrees in 1 box but next to it 1 or 3 degrees with the same change so DO NOT extrapolate or flatten the tune to smooth it out change it box by box like each 1 is new by referenceing the DATALOGGING data and make changes based on what you need and flash then see what it did

[tom-hptuner]

i have thought of removing all multipliers and making the engine a simulated distributor and carburator like an old school SBC v8 - I have not tested because it wont work for me because i go up mountains alot up in new hampshire then back to the beach in salisbury

[tom-hptuner]

quick tip !

watching ignition timing at idle can help you determine a misfire or sensor droppout causing a surge or problem

my timing at idle in drive is 17 degree on my 99 cherokee and the pcm commands +1 degrees of timing to correct rpm speed based on how many rpm dropped

so watching it bump rhytmically from 17 to 19 and i can almost feel/ hear it shows an issue - datalog to see if any other sensor dips at same time for me my MAP sensor was flat lining 45 kpa to 99 kpa intermitantly ! problem solved and runs better than i have ever seen now

(the timing speed adjustment is a value we can change to help smooth idle reduce the timing and rpm will drop a lil then come back and you might not feel the surge at all ! )

[tom-hptuner]

ive been using DFCO it cuts fuel off on decel seems like it would save gas but its very hard on drivetrain ! I have stiff urethane mounts and motor trans dont move much and i feel everything in the motor in my seat - dfco instant on and off causes a shutter when it pops on and cant be good for mechanical parts that wear so im shutting off.

[tom-hptuner]

keep me updated and feel free to ask tips !

i may start a facebook so i can get notifications to help you guys faster - ive had life issues and just got back to the jeep project 1 year later

[tom-hptuner]

i started having an issue with O2 sensors not responding and stuck in open loop 100% after it was flashed last night and drove fine last night - today no closed loop WTF im working the problem and post findings maybe ill reflash pcm and maybe just bad write to pcm hoping pcm diddnt shit the bed or get damaged from writing to it !

[Gordon-0]

Hello all, looking to purchase an MPVI3 to tune my GM car but it would also be great if I could tune my 02 Jeep 4.0. I see that on the list of supported vehicles HPT is saying you can do it with the V3 but Tom said that you need V2... what's the deal?

Second question, after a cam swap and many other vehicle / suspension changes I am getting a huge amount of "bucking" caused by fluctuating idle rpm while idling in gear. Also (possibly related) this jeep has the strongest engine braking of any vehicle I have ever driven. I'm wondering if the jeep ECU has similar timing / fuel tables to GM that make it easy to pull timing off throttle to reduce the engine braking effect? Can I tune the idle for better stability?

Lastly, I have an electronic speedo sender. It is pretty close to accurate, but not quite right. Can I reprogram the ECU to correct this?

Thanks for the help.

[scottie1134]

FYI you need an older HPtuner 2+ to tune jeep engines

So are you saying the first version of the MPVI2 is not going to work on these early model jeeps? Because I haven't had any luck on my module. I got one of the first releases of the MPVI2 modules.

[hyperbolecubed]

I swapped my Jeep grand Cherokee from a 42re to ax15 manual transmission and resulted in CELs for the missing auto trans. I?ve disable the codes and reflashed the pcm, deleted the dtc remnants and went for a drive to find the codes are still populating. Just looking for ideas on what could be done next?

[Greenstreetml]

I did add a banks header and 12 hole injectors. LTFT seems to be about 4% rich at 2000 rpm and below. Should I concentrate on Open Loop/Base tab and the fuel base tables?

[Greenstreetml]

Greenstreetml said:
3 Minutes Ago
Not sure about needibg Mpv2. I am using Mpv3 and beta software to write to my jtec ecm. I set the timing to 32 degrees at 2500 and up based on power nation videos regarding endine builds. I do not have any hestitation on the stock engine with 235k miles.