Really Lean Idle, Upgraded Injectors R34Gtt

[Bratva]

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

[Bratva]

Injectors are the same brand/type just bigger flow. Would it have something to do with the injector latency ?

[Bratva]

Also i have the narrowband disconnected is there an option to not use it

[GTSBoy]

350km drive to the tuner = swap back to the original injectors and don't put the new ones back in until you drive it into the workshop.

[Moodles2]

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]

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 November 23, 2012 by rob82

[DVS JEZ]

Just raise the latency a bit.

[Bratva]

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 ?

[GTSBoy]

You might as well plug in teh narrowband. You'll be on proper mixtures on cruise if you do.

[Moodles2]

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.

[GTSBoy]

But there's no real reason to deactivate it. Just leaving it working will be the best for a long steady drive.

[Bratva]

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 . 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.