Jeep Strokers

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 flash pak. 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!!!

This is wonderful to hear- I´ve been communicating with Ryan via email and am currently adding an SSI-4 to my LC-1 so I can datalog the things he needs to set up a tune for me. Congrats on the setup.

As for me- I´ve managed to achieve a proper AFR via piggybacking, but obviously have zero control over spark advance or anything else. Are there really significant open loop power gains that you´ve noticed from the timing adjustment?

P.S. The fuel econ part is surprising- I eek out about 12mpg on a good day, but I do a lot of highway driving and have 35s- highway driving a lifted rig with 35s just guzzles gas. I´ve never complained about it much because I´ve never expected any better than 12mpg, but if you really are achieving better mpg with the new tune that´s a nice little bonus.

My WJ stock on 29.5" got only 14.4 mpg (math verified not EVIC) since new. The stroker improved mileage some but I have enough TQ now down low after the tune to be able to just lightly press the gas and allow the tach to sit on the 2100 mark and just glide up to speed through the gears. It would not do that before the tune even with the AFR set.
The increase in power and driveability I attribute majorly to the timing algorithms being adjusted to match the cam. For example I have large cam with some decent overlap, this means the engine will like more timing down low. The factory PCM wont put that much timing in so it leaves low RPM light load power on the table. The biggest difference is the linear power feel of the engine, it has power anyplace anytime at any rpm range. Obviously the cam comes on hard at 2500 but my TQ below that range is still so strong that I can cruise 70-85 at 2200 or below without much pedal at all. I am running the Goodyear Kevlar MT's which are lighter due to Kevlar but I noticed a big difference with the lift and larger tires so I can only imagine your 35's are much heavier. I would have gone 35 if they would clear but I already had to the cut the front bumper to clear the 32's on the WJ. Ryan really seems to have how the JTEC PCM behaves down to a science, I was going to tune mine myself until I met up with him and figured why try to learn what he already knows? Once its tuned I am done and any changes I make (planning on building my own custom intake soon likely using a dual barrel TB off a 32v 4.6 cobra motor with shorter runners, more cross sect area etc) I think the stock intake is never going to allow more than 275hp, and i know my combo can make 360+ at 6800 rpm without exhaust enough intake. The stock intake with a 65mm TB still pulls 4" of vac at WOT !! I am going to recheck this again after the tune is dialed in. Get it all tuned I would bypass the piggyback unit and have fuel/spark tuned in unison so they align optimally for all conditions.

http://www.youtube.com/watch?v=5yEyAk0VDww&feature=plcp

Idle is just so solid now.. even in gear with AC on.

That sounds like one mean mofo. Awesome!

Its finally getting there thanks to Ryan!!
He really gets the magic of how the OBDII JTEC likes to invade different areas of the tune based on the adaptive fuel trims. Its a tedious process to tune each area carefully, slowly, test, log, change, test log. Then the magic of blending all those areas together and doing so in the right order is an art form. Of course a large cam like this adds even more complexities. My idle vac is only 10" in neutral .
The tune we loaded last night has this thing really moving now, Ryan spent a considerable amount of time getting the important stuff right, cold start/ warmup fueling, idle warm/cold spark maps which affect idle speed and mix. This truck now fires right up and settles out instantly even in 42 deg weather without any stumble or shake, warms up nicely and drives like a stock 4.0. This is going to sound insane but if I remain under 70mph i can eeek 23 to the gallon out on the highway! I ran a 48 mile trip Sunday morning filled the tank to the top (changed fuel pump/sending unit just to ensure I had a new one) drove the 48 miles then refilled and did the math. EVIC was showing 25mpg hahahh no way but 23 suprised me. City mpg now is about 16.2 if I stay off the pedal too much not bad for a built/cammed lifted 4x4 on 32" mud treads with 3.73 gears and clutched diffs. Throttle progression is drastically different it pulls like my M3 now if you leave it in say 1st/2nd gear and just place your foot at say 1/4 throttle it will pull effortlessly to redline without having to continually feed more pedal to it to make it climb. Before it always felt like I had to force it to rev, now its just plain rev happy.

funny thing.... were not even done yet he has even more tricks up his sleeves! They must be some long sleeves

COOL!!! Good to know. I am rethinking my next engine. I was going to go with a 5.9 engine swap, because I wasn't real happy with my last stroker. It ran good, but I wasn't impressed for all the time, money and work spent on it.

if I could have fit a good v8 in this one I would have gone that route. I have a v8 limited 03 and its a dog compared to this one and the v8 has 5 gears vs 4 and only 2whl drive on smaller tires. given the choice of stoked or lsv8 I would do a warmed over 6.0 any day. Lighter larger and make more power.

superstingray77 wrote:if I could have fit a good v8 in this one I would have gone that route. I have a v8 limited 03 and its a dog compared to this one

That's because I'm not tuning it.

FlyinRyan wrote:

superstingray77 wrote:if I could have fit a good v8 in this one I would have gone that route. I have a v8 limited 03 and its a dog compared to this one

That's because I'm not tuning it.

Email sent

Replied....

It is great hear that your engine run so fine.
I am very surprised with your improvement in gas mileage.
I am not very happy with my current Split-Second FCT-019 (neither with my gas mileage) and for some time ago I am thinking to install a MegaSquirt 3 (MS3X) on my Jeep and tune the engine and the torque converter lock up.

montelibre wrote:It is great hear that your engine run so fine.
I am very surprised with your improvement in gas mileage.
I am not very happy with my current Split-Second FCT-019 (neither with my gas mileage) and for some time ago I am thinking to install a MegaSquirt 3 (MS3X) on my Jeep and tune the engine and the torque converter lock up.

FWIW- I had tuned my stroker with a piggy back and a wideband before, and had achieved an A/F I was happy with, but decided to go with Ryan anyway- he is able to completely alter the timing maps, as well as dial in a/f for closed loop, so that you are not lean under partial throttle as you would be with the piggyback and stock maps- I still have another iteration to go through with him once I can get past all of the holiday obligations and stress, to get one more tweaking, but I will say this- after a single baseline map and one followup map, after some logging and feedback from me- the jeep runs WAY better than I ever could have gotten it. I'm slightly rich under low-throttle conditions on the highway, but the low-end torque delivery and idle smoothness was improved in a way that never would have been possible with my piggyback.

Ryan's knowledgable and responsive, I would definitely recommend him to anyone. Feel free to PM me if you want any other feedback on the process- I totally vouch for his legitimacy and his product.

-Chris

So, Would this tuning be something that would be recommended for a stroker running the stock camshaft? The only changes from a stock motor in my build is: .040 overbore, 258 crank, TB with taper removed and a '99+ intake.

I would recommend a PCM tune for even a stock vehicle. There is so much that can be done besides ignition timing and air fuel ratio adjustments.