WOT Box + AEM AFR Failsafe Compatibility Issue?

[BuddySpeed3]

Hey everyone, I've just recently installed the SP63 6th port aux fuel injection kit into the car. Started tuning and so far so good with no fuel leaks, good low side fuel pressure, and nice cool bat's (mixing 2 gallons of in tank meth).

I decided to install a fuel pressure gauge, oil pressure gauge, and most notably an AEM AFR failsafe gauge. I've also installed an N2MB WOT box to prevent a lean burn during Flat Foot Shifts, and when hitting the rev limiter.

Since the aux fuel system will keep spraying during these two occurences, a dangerous lean burn is possible since the oem rev limiter and FFS feature will cut the stock injectors, and not ignition like the WOT Box does. (Thanks Nishan)

The problem I'm having is that the AEM AFR failsafe is triggering my Guardian angel during a WOT box FFS. I noticed in my logs that there is usually one cell that displays lean to about 29:1 during a FFS, but I'm assuming this is because the oxygen is detected by the wideband sensors, since it's not being used in combustion when the WOT box cuts the ignition.

Since I have my WOT box ignition cut set to 250 ms, I tried setting the AEM failsafe trigger delay to 300 ms, but the Guardian Angel still gets triggered by the AEM failsafe during a FFS, and causes boost not to return into the next gear.

Is it possible that I need to set the delay on the AEM failsafe even longer?

Thanks!

[Fstrnyou]

Turn off FFS feature in the tune and let the WOT box handle it all.

[BuddySpeed3]

Originally Posted by Fstrnyou Turn off FFS feature in the tune and let the WOT box handle it all.

Thanks, I've set FFS and rev limiter in ATR to 9000 rpm which is way out of reach.

This has prevented the OEM injectors from being cut during a FFS with the WOT box, and allows the WOT box to act as a rev limiter cutting ignition instead of fuel.

Having the FFS feature in ATR set to 6700 rpm would interfere during a WOT box FFS by momentarily bringing the IDC down to 0.

The problem is that there is still a lean mixture detected by the OEM and AEM wideband sensors even though the injectors continue to spray (I will post a log tonight).

I figured that this was why the AEM failsafe was triggering the Guardian angel.

I thought that setting the delay on the AEM failsafe longer (300 ms) than the ignition cut on the WOT box (250 ms) would prevent the GA from being triggered, but it doesn't.

I'm trying to see if maybe the delay on the AEM failsafe needs to be set longer

[Fstrnyou]

The lean condition sort of makes sense. The O2 sensors are reading a lot of O2 because it's not being burned. The fact that there is a shit ton of fuel in the exhaust is irrelevant to the O2 reading.

[BuddySpeed3]

Originally Posted by Fstrnyou The lean condition sort of makes sense. The O2 sensors are reading a lot of O2 because it's not being burned. The fact that there is a shit ton of fuel in the exhaust is irrelevant to the O2 reading.

Exactly, and btw I decided to increase the AEM failsafe trigger delay from 300 ms to 400 ms and found that now it works. Having it set to 300 ms was a little too close to the 250 ms ignition cut in the WOT box which would cause it to trigger the Guardian Angel.

Here is a log of a FFS with the WOT box on the stock fuel system. I short shifted at 5600 rpm and you can see that the O2 sensor reads lean for one cell.

Wot Box Test.csv

You can see how this thing benefits because boost only dropped down to about 9 psi. I was hoping it would stay a bit higher but it tends to vary from shift to shift.

It's definitely a great tool for straight line acceleration, and a must for aux fuel setups to prevent lean burns.