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VR6 12v First Crank


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First time wiring an ECU and I think we're getting close.  It's finally cranking and making noises but not quite idling yet.  I thought the header had a hole in it at first.

I've tried a number of things

  • Trigger offset of -84 or 276 (and played with ±10 degrees)
  • With a timing light set to 0 the marks on the crank pulley lines up best at 6 degrees BTDC in the calibration settings
  • I tried adding +10% fuel on cold start cranking table across the row (@ +20% there's backfires in the exaust)
  • I pulled the spark the plugs and tested the pairs that are firing to ensure that they fire per the firing order 1, 5, 3, 6, 2, 4:
    • IGN1 - Clyinders 1&6
    • IGN2 - Clyinders 2&5
    • IGN3 - Clyinders 3&4
  • If I crack the throttle a bit it idles roughly like in the video but on it's own
  • Weeks ago I verified the injector wiring with a volt meter before installing the intake manifold

Other things worth mentioning:

  • ECT signal is from a linear 0-5v out from an AEM gauage which is reading ~10 degrees higher than the gauge itself.  Although I did calibrate it against a chart from AEM.  I assume this doesn't matter though.
  • The motor has 276 cams, 11.75:1 compression and MS109 fuel
  • Link 1.15 bar MAP sensor
  • Link LSU 4.9

Tomorrow I plan to check if ever configured the idle stablizer valve.  What else should I try?


Trigger Scope - Waves.llgx

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Attach the tune and a PC Log.  

Your trigger scope shows some teeth on the trigger wheel arte either damaged or magnetised or something, but Im not sure if that is the only problem without seeing a log.  


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I haven't touched any of the fueling parameters other than experimenting with some of the cold start settings.  I did try lowering the trigger 1 arming threshold by 0.1 across the row and tried setting a target idle rpm of 1200 in this last attempt.

PC Datalog - 2024-01-21 9;15;32 am.llgx Trigger Scope - 2024-01-21 9;16;05 am.llgx corrado_20240119_01_idle_rpm_1200_and_isv (1).pclx

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In the log it looks like it is a lack of fuel, the RPM increases when inj PW increases and it appears happiest when the crank enrichment is dumping extra fuel in.

Assuming it does actually have fuel pressure, then try adding about 50% to the current master fuel value. 

It looks like the trigger wheel is not causing any issues at this stage, but there is definitely something wrong with that wheel and will need to be fixed before the engine is run under load.  

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I tested fuel pressure before the fuel filter and before the fuel rail.  It held >60 psi for 10 minutes after priming the pump in both locations.  I also replaced the fuel filter while I'm here.

I then tee'd the fuel pressure gauge inline with the fuel rail and watched it as it was cranking.  It stayed in the 55-60 psi range.  This was with an additional 50% fueling.

I also logged the PDM this time.  I'm dubious there's anything useful there.



corrado_20240122_00_50_fuel.pclx PC Datalog - 2024-01-22 6;35;13 pm.llgx Trigger Scope - 2024-01-22 6;35;29 pm.llgx 20240122_00.pdmlog

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I dont see anything obvious now.  I would try a spray of starter fluid to quickly rule out fuel related possibilities.  I notice you have an ignitor on the firewall - what is the ignition coil off?  Does it have 4 pins?  

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I got it to idle on it's own by cranking with the throttle open a bit for a minute or so.  I think the header is either cracked or has a hole in it.  I've not run these headers before.

I did try a number of things before starting it.  Ran a seperate shielded wire for the trigger signal to the ECU, swapped crank position sensors with an older one and I swap out the spark plugs.  I didn't snag any logs unfortunately and the trigger scope looks the same.

My next steps are to swap the headers and figure out why the killswitch didn't work.  I apologize for the music in the background.  I couldn't hear it over the exhaust.


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  • 2 months later...

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