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Discussion Starter · #1 ·
This is not aimed at the tuners as i'm sure they know what they are looking at.

I've done a few logs now and i have looked at the data.

Most of the stuff makes no sense to me, outside knowing that my 0-100 time, with a couple of bouts of traction control kicking in, is 7.22 seconds (all done on a private road)

For those Amateurs (for want of a better word):

What data do you look at?
For what purpose?
And what sort of figures are desirable/expected?

Hope this hasn't been covered elsewhere. If so, please just link that thread.


3,684 Posts

send me over the datalogs or welcome to post them on datalog thread on other forum. can't attach files on this forum.

with latest firmware update you can log x 30 important parameters some more important than others

usually ask for-

AccessPORT Feature: Datalogging

Set datalog list-

Ign Advance
Theo Pulse
Boost Right
Throttle Position
Mass Airflow B1 b2
Injector Pulse b1 b2
Air Fuel Sensor B1
Air fuel sensor b2
Vehicle Speed
Knock Sums
A/F Correction B1
A/F b2

Knock-The ECU actively reduces timing in response to detonation. Timing adjustments in response to detonation are logged with the “knock Sum” monitor. Each degree of removed timing is reflected by a -300 knock sum
increment. Generally speaking, higher ignition timing supports higher torque and greater power. Higher timing also yields higher cylinder pressures and this is limited by fuel quality and the mechanical limitations of your engine. Too much timing will produce knock correction when fuel quality is limiting. If increased timing does not increase torque the extra cylinder pressure is simply producing unnecessary stress on engine components.
We keep below -1000, although the oem map can knock as high as -2000 on low grade fuel, pulling timing before any damage is done. In the cobb maps we can program a safety net so too much high knock the ecu will drop into a low grade fuel map and reduced timing. If knock is seriously high over 10,000 ecu will go into safe mode.

Your MFD will flash if it detects knock event of over -700

Generally harder you use your gtr, i.e track with lots heat more knock will appear. one argument for road mapping vs dyno

Maf- Depending on climate most GT-Rs will max the maf voltages around 600hp. Beyond the limits of the stock MAF sensor (5.0 volts) the ECU has no way to properly control/calculate and deliver the correct fuel mass to the engine. If maxing 5v a larger intake will give you more MAF resolution at the upper rpm's, even with stock turbos. leaving 10% spare IDC and 0.1 spare (to 4.91V, so about 4.8V max) MAF voltage to allow for the extra airflow in winter when you are tuned in summer, especially on dyno that is hot and might not load up the engine like a cold day on the black dyno, you start to lose resolution in the upper voltage ranges.

Maf voltages should be close on both banks b1 b2. larger than 50 there maybe an issue, banks need balance or intake/bov unsetting.

Injector duty/pulse width- OEM 570cc injectors hit 100% duty @ 21ms @ 6k. A typical GTR with stage 2 remap 17psi boost falling to 15psi with stock airbox and oem downpipes will see 17-18ms @ 6k.
Anytime you increase airflow (intakes, downpipes, intercooler etc), you should increase your fuel flow capabilities. Injectors may not make power, but it never hurts to be able to fuel the car safely.

AF correction- although your on oem airbox/injectors its good to keep eye on the amount of fuel the ecu is adding/removing to hit our fuel targets. as close to 100% good and the ecu does great job of that especially on oem parts. when going aftermarket we need to help the ecu :)

AF sensor b1 b2- The ideal air to fuel ratio depends upon fuel quality. Higher ron/oct fuels are more detonation resistant and therefore can be run at leaner air to fuel ratios. Leaner Air to Fuel ratios produce higher power but also create more heat. Excessive heat can lead to detonation. Lower octane fuels such as 95 RON are more prone to detonation and therefor require a richer air to fuel ratio. Rich air to fuel ratio combustion produces less heat and therefore less detonation. We have found that the GT-R engine can run mid to high 11 Air to Fuel ratios when running quality fuels (wideband/ af sensor new) (af 12.5 on factory wide band af old parameter) at top end rpm. Lower quality fuels require mid to low 11 air to fuel ratios (low 12's on factory sensor/ af old).

boost- stage 2 cobb map is 15 psi midrange tapering to 12 psi at redline. most custom tunes are 17psi to 15psi. With a proper tune, the v200 boost control can virtually completely avoid boost spikes commonly encountered during flat foot shifts, as seen on oem air flow controlled system.

Vehicle speed- try not to log over 150mph on public roads as generally that leads to custodial sentence

Lots more to it i've missed some parameters but i'm real slammed busy. send me your logs and i'll adjust where/if needed.
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