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Issues starting RB26 in R34 GTR with PRP Trigger Kit


Amrit Sidhu
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I am new to the forums here and seeking help with starting the engine. I have read and searched for trigger issues and starting problems and unable to find solution to my setup. 

The car has not run in about 15 months and in that time I have done several upgrades, mainly:

  • Link G4 NGTR ECU
  • Greddy CAM Gears (set at 0 degree adjustment)
  • PRP Crank and Cam Trigger Kit (Crank is TRIG1, Cam is TRIG2)
    • CAM's PIN was oriented facing the dot on cam pulley's timing mark.
    • Crank had one tooth shaved opposite to crank key per PRP's instructions
  • 2 x 10 bar syltech pressure sensors (not working atm)
  • Bosch 1000cc injectors
  • Fluidampr 610911 Harmonic Damper/Pulley
  • GT2860 -5 twins
  • Link CAN-LAMBDA kit on CAN1

As I start the car, it cranks over endlessly without any signs of firing. I have attached the tune file and several trigger scope files to help with the issue. The trigger offset is set to 107* by a friend who also has experience tuning cars. To reach 107* the CAM plate (the one that holds the cam sensor) was turned clockwise all the way. I believe this is known to work in other similar setups.

The engine speed is read around 200rpm when cranking and by understanding of trigger scope tells me that they are also setup correctly.

Timing is locked at 10* and confirmed with timing light.

amrit_gtr _initial_tune.pclx PC Datalog - 2022-07-17 5;32;30 pm.llgx TriggerScopeLog_0717_1.llgx TriggerScopeLog_0717_2.llgx TriggerScopeLog_0717_3.llgx

Audio clip attached when cranking

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Moved to G4X section.

Scope looks ok and the ecu is happy with the pattern.

If your ignition timing looks correct with a timing light but there are no signs of life then that would likely suggest you are 360 deg out - ie sparking on the exhaust stroke rather than the compression stroke.  

To fix this you either add or remove 360 from your offset.  In your case you would remove 360 so try the offset at -253.

 

 

 

 

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I tried with -253 and seems to be no different. Tried again with 107 after and same. What should I be checking next?

 

When using 107* every now and then once in a while it will sound like wanting to start for a split second.

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I just looked at a couple of files I had from other GTR's with PRP triggers.  They didnt have one tooth ground off so their offset doesnt translate directly to yours, but if I look at where their #1 spark occurs compared to their cam tooth position (I expect your cam tooth should occur in a similar position to theirs), then I come up with offset numbers around either +150 or -210 for you.  

That would be about 40deg more advanced than you have it now.  Some of that could be due to the cam sensor being in a different position though.  So since you say you have an occasional hint of it catching at 107deg, that would suggest you are probably firing on the right phase.  Can you try your offset at say 120, 130, 140 just in case the other guy has got that offset wrong somehow.  See if it sounds closer to running with these offsets.  Also bump your master fuel up to about 10ms.    

 

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It just fired up when set master fuel to 10ms but ran VERY RICH! I tried bringing it down to 9 and then 8ms and now it refuses to start again. I didn't change the offset yet because I wanted to try one thing at a time.

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  • 2 weeks later...
On 7/30/2022 at 1:29 AM, Gsab said:

The std offset for the PRP pro trigger is 287 deg.Hope this helps.Yes, its fixed offset.

His is not a pro trigger though, it is one of the 12tooth ones that has been modified to 12-1 by cutting a tooth off.  

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Sorry I didn't update the thread. I finally got it after adjusting offset to 113*. The main issue was however the fuel pump control. I had done the fuel relay mod which wasn't triggering the fuel pump when cranking. The fuel pump would prime fine at ignition but won't turn on at cranking. So I had to change from 3 speed control to standard relay and master fuel trim was reduced to 4 ms eventually. Using Adam's layouts, on Cold Start page there were adjustments to be made to fine tune the idle. Thank you everyone who helped with this so far. 

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