BNR32 AFMs Voltage not same

[koopsta]

I recently installed my Nistune Type 2 board on my BNR32 GT-R. With this program I learned that my STFT and LTFT were deep in the negatives, so thanks to Nistune I was able to balance out my trims to about -1 at idle and 0 when driving. Ignore the Trim numbers in the picture as this is a before changes recording.

However, I realize that my recording shows my Left and Right side MAFs voltages not matching. Sometimes by an extreme. At cold idle they are equal at 1.0 volts. Warmed up the Left Side is about .8 to .9 at idle and Right side is about 1.1 to 1.2. While driving they can be mostly separated by .1 to .3 volts (Right Side is always higher). My attached chart shows the extremes though. The Left side is dropping to .3 volts and the right side is settling at 1.3 while cruising at this shown point.

Is this a sign that my LHS MAF is going bad? If not, how do I fix this voltage drop and fluctuation using Nistune? I have stock R32 AFMs and an all stock engine. Only mods are no air box with pods, test pipe, and catback exhaust.

Andrew

[Matt]

Try swapping the MAFs over and see if the problem follows

0.3 volts is very low and likely to trigger a DTC error code. Does Nistune display any fault codes in the Consult view panel?

[koopsta]

Swapped them and the voltage drop remains the same side. Also the DTC says 55.

[Matt]

Next thing I would check is use multimeter with probes into ECU plug and then seeing if this shows the same. Get someone to watch the multimeter whilst you drive

May be wiring issue perhaps? Normally MAFs should not read less than 0.5 volts

What do the MAFs show with just key on? What do they show at idle?

[koopsta]

Matt,

Here are the numbers. I have not been about to see the voltage at the ECU. The car seems to run normal and doesn't act out of place when the voltage drops. Also it only dips really low when I let off the gas and then gradually gets close to the RHS.

Cold Idle
LHS 1.08
RHS 1.23

Cold Off
LHS 0.215
RHS 0.15

After drive idle
LHS 1.025
RHS 1.155

After drive off
LHS 0.215
RHS 0.150

[Matt]

Well ECU is measuring the numbers okay, the difference in voltage doesn't follow the MAFs when you swap them, so just means that one side is measuring more airflow than the other. The ECU takes both sides and adds them together in the end to balance them out so I think that should be okay