Loki Posted November 19, 2017 Share Posted November 19, 2017 I bought the car FGX turbo with hi-flow turbo, dump pipe, exhaust, crow valve springs, KPM 1000cc, bigger intercooler, battery relocation, big air intake pipe and BMC filter, etc. I had some tune with some tuner from the forum, he used KPM data for the injectors. His tune is average to me but the drivablity is very good and so is fuel economy. I data log the car and found out the short term fuel trim for idle all the way to 4000rpm is nearly zero. My ghost so good! Then I had my car tuned with my tuner who did not try to get KPM injector data and he has his own way of mucking around with the calculations for all the parameters for injector settings as you see in the attachment. The difference between his calculation vs KPM data is massive. This might be the reason for some symptom that I noticed. In the attachment you can see the jig saw for short term fuel trims, economy suffer a little bit say the other tune has average of 12L/100km and this tune has 12.5-13L/100km. I am a fussy owner and I would like the current tune to behave close to stock as possible and I strongly believe with the KPM data my car will be more economy, smoother idle and close to perfect fuel trim like the other tune. The 355rwkw has some mod to the fuel pot (bigger hole for return line or something) and fuel regulator are modified too as a result the fuel pressure change a little compared to stock? My fuel pump is Walbro 460 which should be sufficient for more power later and E85 tune, but that is a long way. The tune is good but not perfect, the reading AFR from exhaust is close to what is commanded in the fuel table - good enough. My interest is to get short term fuel trim to be a flat line close to zero and smoother idle, smoother acceleration enrichment and such, solid AFR curve for WOT on dyno. I have to wait till mid Jan 2018 to see my tuner again. If I can not sort this out myself then I will ask my tuner to re-config the injectors with KPM data and then scale injectors, my fuel, idle, etc around that accurate data. I spoke to KPM when I asked for the data and David said my tuner should enter the data exactly as it is and tune around it! Now my question is say I input KPM data now, what to expect and how to go around it with the old data that my tuner calculated and make fuel trim more solid? Should injector deadtime be exactly the same with KPM data and never tweak them? I can only change low/high slopes and break point? leave PWM alone too? Our goal is to make sure at all RPM the fuel trim stay close to zero yes??? I can try the log when the car is parked, just hold RPM 1000, 2000, 3000, 4000 and confirm STFT is close to zero? Then drive the car around light load (throttle), data log STFT again? Then do some WOT run? If they are not as expected say rich/lean at different RMP then please give me some pointer how to achieve the perfect STFT. Quote Link to comment Share on other sites More sharing options...
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