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Thread: Newbie tuning saga of my LS Jeep TJ

  1. #1
    Fuel Injected!
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    Newbie tuning saga of my LS Jeep TJ

    I hope I'm in the correct place for this thread. If not moderators please inform/correct me.

    I am working on a 2000 Jeep TJ that has had a 2000 Silverado 5.3 transplanted. I did everything myself so far but am not doing so well getting it to run properly.

    It actually runs fine but seems to be getting more and more lean the more I drive it. It's to the point now where I'm getting nervous about driving it for fear I'll be burning a piston or something.

    This thread is kind of a continuation of my introduction post here:

    http://www.gearhead-efi.com/Fuel-Inj...3085#post83085

    Thanks to user steveo I have been able to start focusing on fuel delivery before I try to do any tuning on this setup.

    In my intro threadf (in case anyone hasn't bothered to check it out) I have determined I wasn't getting proper fuel pressure when I started revving the engine. Today I decided to disconnect the vacuum line on the rail mounted regulator and test again before I start replacing parts. I linked a video in that introduction thread.

    Since then I have taken the Jeep for a test drive and recorded the wideband gauge to watch the AFR. It definitely runs rich at idle now but still goes lean on acceleration.

    Here is a shaky video of that test.

    https://www.youtube.com/watch?v=osLMYH3iFbM

    At this point I think I need to determine if it is a vacuum leak or a faulty fuel pump causing my lean condition. Or possibly the regulator restricting fuel flow? I was suspecting a vacuum leak early on in this swap but thought I had that ruled out. Now I'm not so sure.

    I'm a complete newbie to EFI but I have rebuilt a few engines in my day including a 6.2 diesel a first generation 5.7 Chevy small block and a Jeep 4.0. I'm not a complete stranger to turning wrenches but I consider myself a shade tree mechanic at best and am ready to learn EFI.

    If anyone has any suggestions I'm open to any and all.

  2. #2
    Super Moderator dave w's Avatar
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    Can we figure the wring and flash are 100% correct?

    Figuring the wiring and flash are 100% correct, are there any error codes?

    Often the oxygen sensors are the cause for running rich. A flat line voltage from an oxygen sensor indicates a faulty oxygen sensor.

    Have you read the exhaust manifold temperatures on each cylinder with an infra-red thermometer? A healthy engine will typically have every cylinder with about the same temperature. If the exhaust manifolds are not equal, the injector or the coil for that cylinder could be faulty.

    If the fuel and spark are good, then look at the MAF frequencies. Higher RPM's = higher MAF frequencies.

    EFI --- Fuel (injector) / Air (MAF) / Spark (Coil)

    dave w

  3. #3
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    Thanks dave w.

    I believe the wiring and flash are indeed 100% correct. I do have an engine code for evap related problems. I don't have any evap parts installed on this vehicle. I haven't turned those codes off yet in my "tune". I am using EFILive to tune this because I had already purchased it to tune my Duramax truck. (I will be learning to tune that someday as well.) The EFILive package came with two vehicle licenses so I used one for this swap vehicle. This swap is using a drive by cable setup with a 512kb red blue PCM that I believe to be referred to as a P01.

    I did create a custom OS I guess. I merged the manual transmission segment from one OS into another of the same. The operating systems were both 12212156. Unfortunately I don't remember what was what but I think the manual transmission originally had a 5.7 engine and the auto was a 5.3. Either way the PCM seems to like it just fine.

    I have set up the EFI software to log my from the PCM and do have a wideband (an AEM 30-0334) setup to log using analog into my V2 programmer. In this case the analog input from the AEM is actually faster than serial and was recommended by the guy that wrote some custom firmware for the gauge. I'm not sure if he works for AEM but he seems to know a lot about them anyway. I will also be using that wideband on my next project that is already underway. The wideband I have will communicate directly on the OBD port of my Gen iv (E38) computer used in that project and has a pretty good resolution as I understand it.

    Anyway I do see both narrow band sensors functioning properly now. I did have them wired wrong when I first started it. I had originally wired bank one on the right side and bank two on the left. With true dual exhaust there was no way the narrow bands could properly control the fuel...I have that corrected now.

    When I first started driving the Jeep I was running a bit on the rich side. If I disabled closed loop it would continue running a bit on the rich side. It never runs below 14 now when I'm driving except at idle.

    All the O2 sensors are new but almost everything else is used in this swap. It is a new flywheel and clutch though. My intention for this swap was to learn to tune and have some fun. When I get my next project done I will be selling this Jeep. I expect to have all the bugs worked out by then... I was trying to keep this a relatively low buck swap. So far I've succeeded.

    Here is this Jeep project documented on another forum:

    https://www.wranglerforum.com/thread...#post-34830471

    Here is a link to the Jeep I plan to keep for a long time. It is still on hold but I plan to finish it some day:

    https://www.wranglerforum.com/thread...to-cj.2234433/

  4. #4
    Super Moderator dave w's Avatar
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    I worked on a similar tune several years ago, 5.3 / manual trans. The 5.3 was not offered with a manual. I opted to use a factory 12212156 4.8 / Manual flash VIN 1GCEK14V32Z186112, then update the 5.3 parameter "without" segment swap. I was not satisfied with the outcome of the 5.3 / Auto to Manual segment swap I initially tried. The biggest issue I experienced with the manual segment swap was drive-ability, deceleration fuel cutoff (DFCO) was horrible, even with a VSS!

    The basic difference between the 4.8 and 5.3 are fuel tables, injector parameters, and spark tables.

    I use TunerCats .cal files, which won't work with EFI Live.


    dave w

  5. #5
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    I remember reading somewhere that I should start with a manual transmission OS so I'm fairly sure that's what I did. What I don't remember is how I segment swapped it. I do have a .bin of my current tune. I'm not necessarily stuck on EFI Live as my tuning option of choice. It seems like the obvious choice right now though.

    My end goal is really to have a fairly good understanding of how the modern PCM/ECUs function. I think I have a 30,000 ft view understanding, now I'm trying to zoom in and see how everything fits together. It seems so far that the volumetric efficiency table is the main table that gets used to determine how much fuel to add and other factors like intake air temperature, throttle position and manifold pressure are used to alter that amount? Then the spark advance table plays into that somewhere...

    I don't have a vss installed on my vehicle yet. Everyone says it's essential but I'm not really sure I understand why. My Jeep seems pretty acceptable to me compared to my old sbc gen 1 swapped CJ7. This jeep has more power and gets around the same fuel economy as I was getting in my old CJ7. Once I get the lean condition figured out I hope to get a tune on it and expect to get a bit better economy too. I suspect I may be able to achieve 16 mpg all around.

    I have double checked my engine for a vacuum leak. I did find a minor leak that I fixed yesterday but there was no noticeable change if AFR. I'm resigned to drop the tank and replace my fuel pump at this point.

    For a last ditch effort I plan to try resetting my LTFT and disabling closed loop to see if I can get this engine to run rich again on this pump/line setup.

  6. #6
    Fuel Injected! steveo's Avatar
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    For a last ditch effort I plan to try resetting my LTFT and disabling closed loop to see if I can get this engine to run rich again on this pump/line setup.
    oh god no

    when your AFR is way out to lunch on a stock engine you don't just tune it to add more fuel. that's NOT what tuning is for. fix the problem

    a stock calibration on a stock engine should not run lean under heavy throttle in fact it should run quite rich

    if its truly getting leaner as you drive it that's a sign there's a fuel delivery component that's on the way out

    I don't have a vss installed on my vehicle yet. Everyone says it's essential but I'm not really sure I understand why.
    your ecm will behave differently whether the vehicle is moving or not moving. there may be minimum enable speeds for certain things. totally depends on your calibration/os but a VSS is good to have for sure.

    It seems so far that the volumetric efficiency table is the main table that gets used to determine how much fuel to add and other factors like intake air temperature, throttle position and manifold pressure are used to alter that amount?
    yep, if you're running a speed density setup (no MAF), that's pretty much how it works. a VE table is a map of how much air your engine can move at any particular point of rpm and vacuum. on a stock engine the adjustments to the VE table should be pretty minimal.

    Then the spark advance table plays into that somewhere...
    only in terms of more/less efficient combustion requiring slightly different amounts of fuel.

  7. #7
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    Thanks again steveo.

    Lol, I sure don't plan to tune around a mechanical problem. I just wanted to be sure there wasn't some parameter in the computer that was causing the lean condition.

    Is it possible the GM fuel pressure regulator could be restricting fuel flow even when it has no vacuum line attached? I called my local NAPA and was quoted around $150 for an original OEM replacement so I don't want to start swapping new parts in on a whim. Edit: I just looked on Amazon and see it closer to $50 which I'm willing to spend...

    I'm not opposed to replacing my stock fuel pump. It seems likely that would be the problem since it has moving parts and is probably 20 years old. What I don't really understand though is with the vacuum line disconnected the gauge clearly shows 58 pounds pressure at the rail and it doesn't seem to be dropping while I rev the engine up. This leads me to believe the pump is keeping up with the engine demand and somehow the engine isn't demanding enough fuel or the regulator isn't allowing it in to the engine? Or I guess one other possibility would be all my injectors are plugged up not allowing enough fuel in? That just seems so unlikely to me though.

  8. #8
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    So last night I dropped the tank and started replacing the fuel pump. I used a new Bosch pump. It was the replacement pump for the TJ I had previously and never installed. The only specs I could find for the pump weren't actually from Bosch but this pump is supposed to be capable of over 100 psi. I haven't tested pressure yet but I'm sure it's fine.

    Changing the pump wasn't without incident but I have the new pump in and the tank not leaking fuel now. It didn't help. I'm still running very lean.

    So I just got back from NAPA with a new fuel regulator. I hope to get that installed this evening and see if that helps. It occurred to me this morning (after I already had everything buttoned up for a test) that possibly my fuel line from the tank to the rail has an obstruction in it? It could possibly be that the line isn't allowing enough volume of fuel through but because it isn't a complete blockage I have good pressure?

  9. #9
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    I'm just about at my wits end. I just replaced the fuel pressure regulator. Still no change. Once I go off idle I see the AFR jump to 15-16 and climb to over 18 when I really rev it.

    I'm not really sure what I'll do next...anyone have any suggestions?

  10. #10
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    Post your efilive and/or .bin file
    -Carl

  11. #11
    Fuel Injected! steveo's Avatar
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    are you sure your wideband is okay? when it goes into close loop what are your trims, and what does your wideband say?

    are you sure your bin is correct for the engine?

  12. #12
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    This is what is in the PCM right now.

    I've checked a couple times for vacuum leak but am contemplating building a smoke machine and doing a smoke test at this point. That's all that makes sense as to why it's so lean in my brain.

    I can read this tune out as a .bin if needed. The .bin I have isn't current but isn't too much different.
    Attached Files Attached Files

  13. #13
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    Hey steveo I didn't see your post until I responded to the other.

    At this point I'm not really sure about anything. I really don't think it's a fuel pump or line issue though. My memory isn't really helping but I am fairly sure I used a 5.3 OS for the fuel/timing segments.

    I'll have to go take another log to test things I guess. When you say trims you mean PE? I haven't touched that (yet).

    I'm fairly sure the wideband is correct because I'm starting to get watery eyes when I drive it now. (I don't have the exhaust dumping out proper yet.) Although this isn't usually a problem because I don't have a top or doors on it usually although I do at the moment.

    Everything read normal when I was trying to do the CALC.VET tuning according to the howto at EFILive.

    I'm pretty convinced now though that it was already starting to read too lean at that point and that's why I wasn't able to tune it properly then.

  14. #14
    Fuel Injected! steveo's Avatar
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    I've checked a couple times for vacuum leak but am contemplating building a smoke machine and doing a smoke test at this point. That's all that makes sense as to why it's so lean in my brain.
    that makes the total opposite of sense.

    as you rev the engine your manifold vacuum decreases substantially, and the airflow through a large opening (your throttle plates) increases substantially. this means that the percentage of airflow of a small to medium sized secondary opening (your vacuum leak) can contribute goes down big time. you are experiencing the opposite, going lean at higher RPM but normal at low RPM. if you had a vacuum leak big enough to affect anything off-idle it would also be idling like crap and you haven't mentioned that.

    I'm pretty convinced now though that it was already starting to read too lean at that point and that's why I wasn't able to tune it properly then.
    again, unless you're running a non-factory calibration on a non-factory engine, this is a diagnostic project, not a tuning one. i'm starting to think one of those conditions isn't true, or something else basic like the injectors are not correct or have failed.

    the other oddball thing is you say it has tons of power. there is no way an engine burning such lean AFRs is going to have good power.. i don't know much about the 5.3 but that generation of ECM doesn't use active fuel management, does it?

  15. #15
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    Thanks again steveo.

    Just to be clear I'm not trying to tune around any problems. I'm just trying to correlate symptoms. I'm just a shade tree mechanic. I'm trying to say I think I discovered I had underlying issues while I was trying to tune the PCM initially. That's when I decided I needed to step out of EFILives forum and look elsewhere for help. I have not (and will not) try tuning the PCM until I have the underlying issue corrected.

    I obviously wasn't thinking clearly about the vacuum leak. I was just grasping at straws on my keyboard...

    The engine does seem to idle quite well and is always rich on the wideband. It also has a lot of power even when it is posting 17-18 AFR on the wideband. I'm thinking I will try to log some more to verify what other conditions are showing in the PCM while the wideband is reading so lean.

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