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Thread: Crash course for a base map - '98 Grand Cherokee 4.0 Turbo

  1. #21
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    Yeah, something is definitely goofy there. That looks much better.

    Let me know if 488 with the 2 bar looks close to correct as well and once you've got that, I'll send you a file with the spark and fuel manipulated so you can see a strategy for it.
    If in doubt, multiply everything by 1.1.

  2. #22
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    Quote Originally Posted by spoolboy View Post
    It looks like manifold vacuum is actually the channel that follows in the same direction as the spark and fuel maps.

    One more test. Stock map sensor and stock tune - log manifold vacuum.

    Oops, looks like you're already doing that!
    I think I found a problem.

    MAP was reading 100kPa as shown above...

    I changed the scale and it dropped to the 30s (scale at 122).

    I changed the scale to 200 and the kPa KOEO dropped to 14. I changed the multi 4 or 5 more times.. all different numbers.. no change to kPa KOEO. Stayed at 14.

    For giggles, I disconnected the battery for a few minutes.. reconnected.. didn't change anything and now the same channel was showing 59kPa KOEO.

    With the 2 bar sensor.. it should read middle of the map for KOEO which would be right around 45kPa. Makes sense because a 2 bar sensor reads 2.5 volts KOEO where the 1 bar reads 5v.

    I've been fighting numbers the whole time because of the ECU going funky with the KOEO readings.

    Any idea why it would do that?

  3. #23
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    See the following logs to see what I mean..

    Nothing changed other than disconnecting the battery.

    Stock - 250 Multi KOEO.hpl

    Stock - 250 Multi KOEO Battery Disc..hpl

    Why is it doing this? Do I have to disconnect the battery after every change?

  4. #24
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    Ok.. FINALLY getting somewhere.

    Set the multi at 260 which basically halfed the map. Gave good resolution for both out of boost and in boost.

    Been disconnecting the battery after every change. I've now got it idling smooth with little variation in fuel trims. No more 3k rpm wall.

    Still have to scale the timing.. then drive it and see how it acts.

    It doesn't like cold starts still so I'll likely have to tinker with the cold start enrichment map.

    Adjustments are much easier and faster now that I've set all the charts in Scanner to match the maps in Editor. Newbie mistake but I'm learning.

  5. #25
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    Now you've got me confused. I don't know why you're having variable results from the scanner. Maybe send a ticket to support?

    In regards to my question about the mityvac, you can do a KOEO test using the mityvac to make "boost" and "vacuum" with both of your sensors while logging voltage and kpa. And make notes on what the mityvac dial gauge shows. Maybe see if you get the same results from scanner as you get from your diagnostic tool?
    Last edited by spoolboy; 05-31-2020 at 07:27 PM.

  6. #26
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    Quote Originally Posted by spoolboy View Post
    Now you've got me confused. I don't know why you're having variable results from the scanner. Maybe send a ticket to support?

    In regards to my question about the mityvac, you can do a KOEO test using the mityvac to make "boost" and "vacuum" with both of your sensors while logging voltage and kpa. And make notes on what the mityvac dial gauge shows. Maybe see if you get the same results from scanner as you get from your diagnostic tool?
    Not sure either but I seem to have it sorted. I get consistent results as long as I unhook the battery every time after I flash a tune.

    I got it running and driving now... Idle and part throttle cruise are pretty solid. Boost needs some work but it's getting there.

    For giggles, I didnt unhook the battery on after a flash and it changed the kPa again and threw the whole tune off. Unhooked the battery... hooked it back up.. no re-flash.. and the same tune ran great again. This was during some fuel tweaks.

    Still waiting on support to get back with me on the missing baro correction chart. Once they get that sorted, I'll ask about the issue with having to "clear" the ecu with every re-flash.

    Anyways... onto good news. It idles great when warm.. part throttle drivability seems pretty good. I do have a couple issues which I think are modifier related (I haven't touched anything but the base fuel and timing maps so far).

    First.. It can be idling perfect.. as soon as a drop it into gear, it leans out and nearly stalls for a second or so.. then picks up and is fine again.

    Another issue which may have something to do with the first.. when coming to a stop.. RPM hangs around 1200 for a second or two... then drops back down to the commanded idle speed. Then the transition from low idle (750ish rpm) to take off is TERRIBLE. Falls flat on its face and pegs the wideband lean.. then will catch and take off fine.

    I've got some timing questions too.. but I think I'll make another thread about that. I'm curious what others with boosted 4.0s are running timing wise.. what's safe and what's not. I've pulled a lot out of it and would like to gradually put timing back in it but since there is no knock sensor and no knock retard.. I want to do it safely.

    I'm also curious... why do so many either force closed loop or open loop? Is there a reason to do either?

    Thanks again for all the help. Still a ways to go.. but getting there.
    Last edited by Mr4btTahoe; 06-01-2020 at 12:10 AM.

  7. #27
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    What are your fuel trims like? Are the larger injectors in now?

    As far as timing, I have no experience with boost and 4.0s. I'd start with removing 1* per psi and go from there, watching for knock. If you have access to a dyno you can slowly increase timing and watch for torque increases to fall off or peak while listening for knock and watching for signs of erratic ignition.

  8. #28
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    As far as forcing open loop, it's done to avoid issues where you have boost at low rpm but no fuel power enrichment. And also for large cams with a lot of intake reversion where idle mixtures reported by the O2 sensor need to be something other than stoich for a decent idle.

  9. #29
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    Quote Originally Posted by spoolboy View Post
    What are your fuel trims like? Are the larger injectors in now?

    As far as timing, I have no experience with boost and 4.0s. I'd start with removing 1* per psi and go from there, watching for knock. If you have access to a dyno you can slowly increase timing and watch for torque increases to fall off or peak while listening for knock and watching for signs of erratic ignition.
    Nearest dyno is a couple hours away.. I live in BFE hence deciding to learn and do it myself. Lol

    Currently, once warm, light throttle cruise, I see a few percent fluctuation in the STFT and LTFTs. Idle once warm sees the same.. no more than 3% fluctuations.

    Now I hadn't done anything to the cold side of the tune.. and it needs work as I found this morning. It cold starts great... no stumbles.. nothing. BUT... after a few seconds, it was idling around 10.5 on the wideband. Once driving, it was okish.. but at idle, it was to the point of hazing.

    So.. I need to figure out how to lean out the cold/warmup side.

    Still on stock injectors. At ~3psi (wastegate opening too early).. I'm at 60% duty cycle and 13.8 AFR (which needs to be a little fatter.. I'm working on that yet).

    If I can get 6psi and keep duty cycle under 90... I'd probably not mess with swapping injectors. We'll see though. I still haven't found any data on those injectors so I've got some digging to do there.


    On timing, I had pulled a lot out of it across the board. Now that I've got fuel closer.. I'm going to put the bottom of the map back to stock and just pull timing out of boost. I've got it setup at roughly 1 degree per psi.. just haven't flashed it yet. At work.

    I'm gonna pull the plugs and clean them up tonight as on the way to work, it threw codes for 3 cylinders misfiring (likely because of how pig rich it was when cold).

    So... how do I lean out the cold/warmup?

    Thanks!

  10. #30
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    Like I've said all along, I'm learning these JTEC with you. I've never done one so take what I say here with a grain of salt.

    The standard process would be to find the cold start or warmup tables and adjust them.
    You could also change the closed loop to kick in earlier or later depending on what you need. Looks like tables 34034, 34037 would affect cold running mixtures and 34005 & 34007 would affect starting performance.

    You're going to need the larger injectors to remain safe so I'd stop while you're ahead and put those in before you have to re-do all your current calibration work.
    If in doubt, multiply everything by 1.1.

  11. #31
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    Quote Originally Posted by spoolboy View Post
    Like I've said all along, I'm learning these JTEC with you. I've never done one so take what I say here with a grain of salt.

    The standard process would be to find the cold start or warmup tables and adjust them.
    You could also change the closed loop to kick in earlier or later depending on what you need. Looks like tables 34034, 34037 would affect cold running mixtures and 34005 & 34007 would affect starting performance.

    You're going to need the larger injectors to remain safe so I'd stop while you're ahead and put those in before you have to re-do all your current calibration work.
    Ok. I'll have to get seal kits and info for them.

    I've talked to a few people who are tinkering with these as well and some actually adjust injector settings while some scale the whole base fuel map a percentage based on difference in flow rates. What would be the best way to go in your opinion?

    The JTEC doesn't have many parameters for the injectors. May make a new post about it and see.

    I've found the cold start and warm up tables.. they seem to be multipliers if I'm reading it right. I assume just scale them back like anything else?

  12. #32
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    Scale the whole map by a percent.

    .7 in this case and log with your wideband and watch fuel trims to perfect it.

    I beleive the tables are pulse width adders, but you'll have to log and see for sure.

    Check your PMs.
    If in doubt, multiply everything by 1.1.

  13. #33
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    have you change your min and max map values at koeo under engine diagnostic , also try 50.00 on Map min counts 5v, see if that helps.

  14. #34
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    Quote Originally Posted by Omunoz View Post
    have you change your min and max map values at koeo under engine diagnostic , also try 50.00 on Map min counts 5v, see if that helps.
    What exactly do the last parameters control?

    So after a slight mishap with a 220k mile weak head gasket.. a lean mix and a bit too much timing... I've got some parts on the way. Lol. Felpro PermatorqueMLS head gasket, ARP studs, a new exhaust manifold (mine was leaking.. I'm assuming its cracked)... some DEI titanium header wrap and a turbo blanket will hopefully all be here by Friday. If I get time, I'll get it back together by early next week.

  15. #35
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    Quote Originally Posted by Mr4btTahoe View Post
    What exactly do the last parameters control?

    So after a slight mishap with a 220k mile weak head gasket.. a lean mix and a bit too much timing... I've got some parts on the way. Lol. Felpro PermatorqueMLS head gasket, ARP studs, a new exhaust manifold (mine was leaking.. I'm assuming its cracked)... some DEI titanium header wrap and a turbo blanket will hopefully all be here by Friday. If I get time, I'll get it back together by early next week.
    those are related to key initial baro reading error,i have encounter similar issues about map reading not changing even after a few key cycles or even swapping ecms, i have two ecm's one from 98 stock and second from 99 set to 2bar map values , initial reading was around 50 kpa after a few try's and testing reading drop to 14kpa with 2bar map or stock values, swapped ecm to stock form without disconnecting battery and the readings stayed the same disconnected battery and went back to normal readings , still working on it

  16. #36
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    this is related to baro changing after each key cycle,the scale multi set to 190 giving a reading at koeo 44.8 kpa , i change map 5v lo limit to 50 and is working, I also made changes to min valid initial baro to 6.5898 KPA and default invalid Baro to 55.3657,jeep is idling good , and driving ok so far

  17. #37
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    Just got word that my head should be done at the machine shop later this week. It wasn't cracked which surprised me a bit... but it's getting a valve job, guides, seals, stiffer springs, and surfaced. It's going back together with an MLS head gasket and ARP studs along with 2 step colder plugs.

    Cant wait to get back at it.

  18. #38
    Any updates?
    2004 jeep LJ
    Stock supercharged 4.0, 36lb injectors, 62mm bbk throttle body.
    2017 f250 6.7 Diesel
    2020 Explorer 2.3 ecoboost

  19. #39
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    Quote Originally Posted by jbee View Post
    Any updates?
    Its back together but I haven't had time to work on the tune. Also still waiting on HPT to add something in. Been a bit now and haven't heard anything.

  20. #40
    Thanks for the work you've shared with the JTEC platform.... I have a 92 Dakota that I have plans for. I'll be referencing this threat for sure.