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Really Lean Idle, Upgraded Injectors R34Gtt

Bratva

By Bratva,
in Engines & Forced Induction

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Bratva Community Regular

Bratva

Posted
Posted

Hi,

I have just upgraded injectors (nothing rly else that would affect anything) on my R34 GTT. I have nistune and so i changed the k constant by going through the injector resize option and changed from 725cc to 1000cc.

This brought the k constant down from like 394 to 285. Problem is my air fuel gauge shows about 20 on the gauge and it runs pretty choppy. If i move the k constant up closer back to 394 originally the AFRs drop down back to closer to 14.7.

But if i rev it just a tiny bit it jumps up again.

Any suggestion would be appreciative! Just trying to get the car able to be moved to the tuners 350km away.

It already had an existing tune and ran no problem.

Thanks :)

Moodles2 Grand Master

Moodles2

Posted
Posted

Injector latency is different even between same brand. An example is this pair (Denso made injectors). Sard 700cc 0.65msec, Sard 800cc 0.75msec.. so you can imagine the latency difference between 725cc and 1000cc.

rob82 Mentor

rob82

Posted
Posted (edited)

Bring you min injector on time up a little - they are probably be operated outside the non linear range of the injector... Unfortunately it is not an exact science... Especially when your not taking into account latency.

Edited by rob82
Bratva Community Regular

Bratva

Posted
  • Author
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Hey guys yeah you were right thanks jacked the latency to 1030. Now its idling perfect at ~ 14.7 AFR and rest of the rev range looks good. Might read a bit more instructions next time ;) There wont be any damages having 20AFR on idle ? Also not having narrowband plugged in is also okay on a 350km trip ?

Moodles2 Grand Master

Moodles2

Posted
Posted

Narrowband sensors get damaged when they're not powered as the heater can't burn off deposits. It sounds like you're using Nistune, there's are afew ways to ignore O2 feedback, one of them is to set the minimum engine temperature which the ECU will accept O2 feedback (defaults at 30C) to something high 200C where the engine has no chance of getting that hot, this way they will at least be powered.

Bratva Community Regular

Bratva

Posted
  • Author
Posted

I have my wideband in its place at the moment, so its not connected at all or screwed inside the dump. I prefer to keep the wideband so i can monitor AFRs on the way there, also just read that i can solder some wires to the ecu to simulatre narrowband signal :O. Its MTXL Innovate one. Or since the AFRs are okay i can just plug in the narrowband so cruise is okay and hope not issues.

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