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Random starting issues RB26


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I've been messing with this startup issue for days.... i can't seem to figure out why.

it was never an issue on the G4+. I tried several different settings - old g4+ cold start, Link basemap cold start, setting from another tuner. 3 different settings. same thing. 

it's completely random. sometimes it starts up perfectly fine, next day it would start then stall (1 bang then dies immediately). same for warm/hot engine startup. 

if it doesn't start properly on the first try, it would flood the engine and will take a lot of cranking to start it up again. and it starts up super rich at 0.65-0.68 lambda 

i did 4 different startup logs today.  the 1st one shows lambda at 1.3 at cranking, but the other 3 are close to target. 

the 1st start up almost failed but it started. the other 3 are perfect start ups. 

I tried bigger "pre-crank prime" and lower "crank + post enrich", or lower "pre crank" and bigger "crank + post enrich".  similar results.  1st one seems to have less failed starts. 

 

G4+ cold start Upgarage.jpg

G4X cold start base Link.jpg

G4X cold start Juno.jpg

PC Datalog - 2021-03-22 6;03;34 pm Cold Start 1.llgx PC Datalog - 2021-03-22 6;05;49 pm Cold Start 2.llgx PC Datalog - 2021-03-22 6;10;15 pm Cold start 3.llgx PC Datalog - 2021-03-22 6;17;46 pm Cold Start 4.llgx

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I can't spot anything straight off the bat and although I have a similar engine setup (RB30 with S2 25de head and a 24-1 trigger kit) I haven't actually tuned my main fuel table or warmup enrichment properly yet so issues are to be expected with my setup.

As a side note your wall wetting compensation is massive, I typically have Asynch inj on, a 5% wall wetting compensation and no accel enrichment.

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i know... if any setting will start the car, it should do it every time with the same result. 

on the same setting, one day i can go on without any issue. then next day, first start up fails and floods the engine. 

i didn't touch accel enrich/wall wetting yet, as i want to get the start up issue sorted first.

 

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I would definitely zero out the wall wetting comp for a start, Im not sure if that code is locked out at start-up or not but if not it definitely has potential to cause highly variable injector PW so I would take that out of the equation.

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Just to add to this thread. Been having hot start issues with wall wetting enabled on RB26 and 2JZ, usually between 2-5%.

Was scratching my head as to why it was causing issues, but remembered this thead and disabled wall wetting and starts every time. Still not as fast as G4+, seems like it takes one engine cycle longer.

Can the documentation for wall wetting and asynch injection be improved whilst you are looking at this. Maybe give some worked examples, hard to understand the balance between Async, wall wetting and accel enrichment. 

 

 

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42 minutes ago, 0x33 said:

Can the documentation for wall wetting and asynch injection be improved whilst you are looking at this. Maybe give some worked examples, hard to understand the balance between Async, wall wetting and accel enrichment. 

 

 

I would second this request!

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  • 2 weeks later...

As a note on this it looks like you don't need anywhere near as much first crank prime when you are using wall wetting as they end up doing similar things to each other when starting the engine.

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