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Thread: 5.3 LM7 Terminator X - starts then stalls.

  1. #1

    Default 5.3 LM7 Terminator X - starts then stalls.

    Hello! I recently finished an 5.3 LM7 (24x, Gen 3) swap into my 1991 Volvo 240 project. The engine is stock, no internal modifications, with approximately 140K on it. This is also manual car, with an AR5/LS swap. Engine ran great prior to pulling from donor truck (’03 Silverado 1500). I installed the Terminator X and got everything wired up, did a couple of test fires with open exhaust manifolds/no radiator, and let the car idle for about 5-10 seconds. The car seemed to idle fine for the initial startup tests.

    Roughly a week later I installed a radiator/electric fan and filled with coolant. Started it back up and let it warm up to operating temp to check for any leaks and make sure electric fans were functioning properly. Car idled fine during the warmup period, with the exception of some idle surging as it progressively warmed up. I'll mention this was still with open manifolds. I have cast “block hugger” style manifolds, and the WBO2 sensor is install approximately 6-8” after the collection point on the left (driver’s) side manifold, positioned approximately 12 o’clock (top) of the exhaust pipe. After I let the car warm up I went to put the car in gear and move the vehicle and that’s when my idle/stalling issues began. One thing I noticed is that if I try to give it a little throttle it'll stay running for a few seconds, but it drops RPM/idles down it stalls out. From what I can observe on the handheld gauges the AFRs drop extremely lean and then it dies out. The IAC Position is also reading rather high 50%+. I figured this might be due to having open exhaust manifolds and the WBO2 sensor being exposed to open air.

    Over the weekend I had an exhaust built/installed (WBO2 sensor position stated above did not change) and the idle/stalling did not improve much. So I decided to delete the ECU Config File and start from scratch with a new calibration/setup using the wizard. After recalibrating the ECU, the idle/stalling issues still persist. I went through the list of initial checks and everything appears to comply with the exception of the TPS/IAC harness routing. I’m not sure how these wires can be located spaced apart from the fuel injector harness on the driver’s side due to the way the harness is built and pigtail lengths. I also find it strange that the car seemingly idled well initially, but now it won’t even idle long enough to get up to operating temp. Based on some research, I’m between this being an IAC and/or WBO2 sensor issues, or maybe base calibrations need to be manipulated. However, I know the datalogs below will shine more light.

    Terminator X Config Details/Settings
    Injectors: Stock truck injectors, Multec 2 (PN 25320288)
    Intake/TB: Stock truck
    Cam: Stock – Below 235° duration
    Crank Sensor Type: GM LSx 24x
    MAP Sensor: Holley Internal (ECU Built-in)
    Fuel Pump: Walbro 450
    Fuel Pressure: 60 psi
    Target Idle: 700 RPM
    Target Idle AFR: 13.8
    CL Compensation Limits: +50%/-50% (These were base calibration settings, seem kind of high?)
    CL Compensation Speed: 3
    TPS Autoset performed successfully multiple times
    MAP, TPS, CTS all appear to be reading correct levels.

    I pulled a couple of datalogs and I’ve attached them here along with my Global File. I tried something different on all four datalogs, and no filter/intake was installed during this time, i.e. open throttle body.
    Datalogs and GCF 083020.zip
    Log 1. No changes, base tune/calibration.
    Log 2. IAC blocked off with tape – stalled immediately.
    Log 3. IAC open (no tape), Closed Loop disable – however it still appeared to switch into closed loop per the handheld?
    Log 4. IAC open (no tape), Closed Loop re-enabled.

    From what I could quickly observe on the handheld digital gauges, the RPM drop approximately 5 seconds after startup, AFRs go very lean this seems to coincide with the ECU switching from Open to Closed Loop, which leads me to WBO2 sensor issue? If I blip the throttle a little after startup it'll attempt to run for a little longer, but then dies out. The IAC readings are also showing pretty high anywhere from 40% - 90% for those first few seconds of running.

    I'm not getting any fault LEDs on the ECU. Depending on when the engine stalls I'll occasionally get a red #6 Crank LED until restarting and then it turns off. The WBO2 Sensor heating LED #3 goes from yellow to green prior to startup and appears to be functioning properly. Should I perform the Brake Cleaner WBO2 sensor test to ensure it's reading/functionality properly?

    Sorry for the long novel explanation. Any help is greatly appreciated as I’d love to get this thing on the road and running properly! Thank you, -Brian

  2. #2

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    If there isn't sufficient exhaust pipe after the wideband O2sensor, it'll read lean on the AFR. And as soon as it goes into Closed Loop it will start to add a bunch of fuel to the Learn Table. Andrew

  3. #3

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    Thank you Andrew. Yes understood, however, I have a full exhaust installed now so there's plenty of piping beyond the WBO2 sensor. The behavior didn't change pre- and post-exhaust. One thing worth mentioning is that I have a shared vacuum source between the OEM FPR and the Holley Internal MAP via T-fitting. I'm wondering if this is causing some issues as well? I understand it's not ideal to share a vacuum source, and my plan is to tap/create a new vacuum port in the spot on the intake manifold close to the firewall.
    Click image for larger version. 

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    Here's a picture of how my TPS/IAC/MAT sensor wiring is routed in comparison to the fuel injector harness.
    Click image for larger version. 

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    And finally, a picture showing the position of my WBO2 sensor. As you can see, it is placed approx 12 O'clock and 6-8" after the cast manifold outlet flange.
    Click image for larger version. 

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    Last edited by bpray9223; 09-01-2020 at 07:10 AM. Reason: Addtl. Info

  4. #4

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    I seem to recall another post that had similar issues and they had their vacuum shared like you have it. I'd monitor the MAP reading and see how it's behaving. It should be fairly stable at idle and increase with quick throttle movement. Andrew

  5. #5

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    Thank you Andrew. I'll take a look, however, my problem here is the engine will not idle long enough to observe a stable MAP reading.

    My first priority will be to tap a new vacuum source and separate the MAP & FPR lines.

    Does anything highlight an obvious culprit from my datalogs, if you've had a chance to review?

  6. #6

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    I see no obvious smoking guns in the datalogs, but I only looked at it for about ten minutes. I'd crack the TB a little, do a TPS Autoset, and give it another go. It might be something very simple. Andrew

  7. #7

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    Thank you sir, l'll try that and report back!

  8. #8
    Join Date
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    Default

    Quote Originally Posted by bpray9223 View Post
    CL Compensation Limits: +50%/-50% (These were base calibration settings, seem kind of high?)
    For starters, try to increase these values to 100+/-.
    Injector Inspector
    USAF 1960-1964
    Drag racing since 1955

  9. #9
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    Default

    Your engine stalls as the After Start Enrichment runs out. The AFR goes lean and it stalls. In the one datalog at this point it was only getting 8 lb/hr of fuel. Probably not enough fuel when it is cold. Your engine has a lot of vacuum, this will put it in an area of the Base Fuel Table that is not giving it much fuel. Your Closed Loop will not come on until the After Start Enrichment runs out, and at this temp point yours is set to stay on for around 17 seconds. Can you keep the engine running if you play with the throttle? Your Base Fuel Table in the area, it's idling is giving it around 5-6 lb/hr of fuel. You could go into this area and up those 9 cells in the idle area to about 8-9 lb/hr to see what happens.

  10. #10

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    Quote Originally Posted by Chuck L. View Post
    For starters, try to increase these values to 100+/-.
    I’ll try that and see if it helps at all, thank you!

    Quote Originally Posted by 81 TransAm View Post
    Your engine stalls as the After Start Enrichment runs out. The AFR goes lean and it stalls. In the one datalog at this point it was only getting 8 lb/hr of fuel. Probably not enough fuel when it is cold. Your engine has a lot of vacuum, this will put it in an area of the Base Fuel Table that is not giving it much fuel. Your Closed Loop will not come on until the After Start Enrichment runs out, and at this temp point yours is set to stay on for around 17 seconds. Can you keep the engine running if you play with the throttle? Your Base Fuel Table in the area, it's idling is giving it around 5-6 lb/hr of fuel. You could go into this area and up those 9 cells in the idle area to about 8-9 lb/hr to see what happens.
    I appreciate you taking a look at the datalogs, thank you! I can keep the engine running for a little while if I finesse the throttle a little, but it struggles to staying running if I lift off the throttle, and even when feathering the throttle it'll cut out and stall.

    Do you think that has anything to do with sharing a vacuum source between the FPR and the Holley MAP? Or possibly clogged fuel injectors? I currently have a 40 micron post-pump fuel filter installed, but I'll be switching that out soon with a 10 micron, as I realized 10 micron is recommended by most systems including Holley.

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