Wild 4.7 I6 Stroker WJ tuning
I recently started tuning a BUILT 4.7 I6 stroker.
'99 WJ 4x4
9.5 CR static
229/236 camshaft solid lifter camshaft, .520/.525 lift, 114 LSA
TONS of headwork- 312 CFM intake/265 CFM exhaust at .500 lift!!!!
ARP hardware everywhere
4" lift, 32" tire
This setup was previously tuned by a professional tuner who is well known for DCX SCT work.
The owner is NOT a member here. But on another forum, this is what he had to say. To give a little backstory about what he is referring to, most of the Stroker I6 community tends to "bandaid" their tuning solution by using a combination of stock PCM, big injectors and manipulating MAP voltage. The concept of tuning through the PCM itself is often considered unnecessary and dismissed by most.
"So... many of you guys have likely come across my threads here, and thanks everyone on this thread my second stroker came out awesome. (first died of cam failure at 2k miles) With both of them I could never get the fueling quite right. The first mild comp cammed one had off idle tip in issues and stalling but ran ok. The second one has a monster solid lifter cam, ported head, 4.7 fully forged balanced & blueprinted ARP everything, Harland Sharp shaft mount adjustables, CNC and hand ported head delivering 312cfm on the intake side and 265 on the exhaust at .0500 lift. Dual outlet headers no cats, ported 2000 intake, 65mm TB. My first tuner who I will not name here tried 8 tunes in open loop to get this engine to run right. It ran like crap with non-linear mixtures, unstable idle, surging, stalling, crappy cold starts I was just fed up with all of it to the point it had just sucked the joy out of my project. I finally resorted to putting the stock tune back on and using the MAP adjuster to get the WOT close to 13.1 and just let the PCM control the rest. It ran Ok, idled alright and got decent mileage but I knew it just was not there different loads and throttle ranges had more power than the others, hard to explain but the power curve just was not consistent and linear despite what you may see on the wideband.
I met Flyinryan on this forum and he offered to take a shot at tuning it using my SCT handheld. His first test file right off the bat was a WORLD of difference the idle was solid rock stead at 800 in or out of gear, fires right up on the first shot every time, runs great even cold then switches to closed loop at proper time/temp without a single hiccup so no more 10 minute idles to warm it enough not to stall out in the mornings. And it just flat out sounds and feels great. Even with my large cam which only has 10" of vac at a neutral idle the truck doesnt rock or shake, just sounds like it wants to tear the wheels off !.
The first test drive was amazing, super solid off idle response, pedal is quick and snappy it pulls so effortlessly now to 75-80 without even breaking 2000 rpm, this is a heavy 4x4 with 3.73 32" Goodyear Kevlar Mudders and a 4" lift and a cam that really does not make power until 2500 RPM. My fuel econ way up from what it was in traffic around 10-12mpg and now its a solid 17mpg on my morning commute. Getting the timing mapped correctly is mega-important. Stock timing algorithms wont work well on a modded motor and previous tuners just locked it at a fixed 32 deg which is crap. Any old timers out there ever lock out both mechanical and vac advance on a distributor and just set timing to 32 deg from 1300 RPM Up??? I certainly would never do this on the street.
Whats this all mean..... AFR is just a portion of the game, the acceleration enrichment, timing maps, dashpot, cold idle, warm idle, scaling the curve to match the vac signal of the large cam and best of all being able to control when you want open loop to kick in but still retain closed loop for idle/cruise and light throttle economy. Ryan is able to trick the ECM into commanding a slightly richer than 14.7 even in closed loop large cams like that added fuel so they dont surge,skip at light throttle cruise etc.
I can go on and on about the difference this made to my truck. Having someone who understands this JTEC PCM and can make it do what we need to match the awesome builds on this forum is worth more than I can surmise in my long winded post.
Ryan has built me 4 files since last night and using my feedback from my Innovate LM2 datalogger he has made improvements that I frankly didnt even think were possible, and were not even close to done, taking baby steps and making certain everything lines up and one change does not negatively affect another area etc. Guys who have cammed up OBD-II setups and have not properly tuned it, give up on timing / map adjusters your barely scratching the surface of what can be done.
Once were all done I will dyno this monster, but best of all driveability!!!"
Due to my workload, please do not PM me as I do not regularly check my PMs. Thank you :)