Nistune Forums

Hello, First time posting. extremely novice tuner. (never intended to tune my car myself)
Stock Head,
Stock Internals
Used:T25 size power enterprise turbine
New: R35 MAF (unsure if VQ map was properly done) tuner did not use the "change MAF" function in nistune.
Used: 740cc Nismo injectors
New: Nismo FPR (2.5 Base pressure)
New: air filter& custom piping w/FMIC
New: Tomei 255 Fuel pump
New PLX wideband
injector O-rings not leaking. (misting looked even when we pulled the fuel rail to check for leaks)


WARNING..SORTA LONG BACK STORY


I recently had Nistune installed on my car. and had a friend of a friend do a house call for the tune.
There is a bit of a language barrier, and he had two days to tune.
He seemed to have gotten the powerband perfect. but as the title suggests. I am burning waay too much fuel in low load situations. 10 AFR@idle and all the way to 3000RPM (with no load) also 13AFR on decel....WTF right?

So since my spark plugs were beginning to drown in soot.and especially because my Vehicle inspection is due in September. i needed to find anyway to reduce fueling. i adjusted the fuel map to nearly 90% lower in the idle cells. with no results. I tried the TP MIN,VQ maps, even touched the timing a bit..No results. Even dropped the fuel pressure to 1BAR for an experiment. the only way i could get leaner AFR results was by drastically changing the injector latency.( a 1000 point drop or so) and at that point, any throttle input was in the "danger zone" on AFR's

So i was forced to put my old injectors in, and use Nistune's awesome autoAFR program to get my car running and able to pass emissions.
AWESOME RESULTS BTW makes me able to pretend im a tuner:P lolz (if i would have known that i could use that program and get safe numbers. I would have done bigger injectors next summer...But oh well.)

okay back story over now. so hear are my questions.

1.Did i waste my money paying for this tune? or is it (salvageable?) depending on what the main issue is of course.
2.I heard Matt talk about nistune fuel maps (running out of resolution) on certain builds. (having to drop to 0 in certain cells and adjust latency) Is this a main suspect?
3.A theory i heard was. Maybe running 740cc Injectors on stock cams makes it impossible to get proper idle and low load AFR?
4.Could weak ignition be the problem? stock plugs stock coil packs ect..?

regardless for now at least Nistune has allowed me to ditch that crumby old SAFC, save money on MAFS, and force me to learn alot of shit.

any chiming in on my little "case" would be greatly appreciated.. Cheers..D.C.

Hey DC,

You've probably fixed this by now but I'd say the tune is "salvageable". And you seem to know what you're talking about.

All you'll need is some form of knock monitoring and you should be able to perfect the tune yourself. Latency on those is typically between about 600 and 900us. Outside of that and you should be adjusting TIM/K Constant.

Fuel map for 740's usually looks something like attached image.

Regards
Pete L

Just email me PL <at> plmsdevelopments.com cos I don't come here often.