Fuel Trim Adjustyment

[DrGonzo]

Can someone tell me how to adjust SAFC2 so that the low/med/hi fuel trims are where they should be??

I just started tuning and the car feels good now with just random 2-3 counts knock which is most likely phantom knock from solid mounts. I was able to get the low in to about 95% from the maxed out 81.2. Now both my Med and Hi are maxed out at 81.2 - 85.8...WTF??

Background on the car is:

93TT with an 10:1 pistons
Stock engine/turbos 360cc injectors
TT ECU with SAFC2
Fuel Lab FPR: Elec FPG "Fuel Pressure Gauge" reads 47psi / Gauge on FPR reads 40psi

FPG is installed right off the fuel filter

Log file can be downloaded here.

http://3s.gonzoinc.com/albums/userpi..._19_11_31.xlsx

[RL7]

If you are adding fuel above 14.7 in places where the ecu is in closed loop, the ecu will try to trim out fuel to get you to stoich. If you subtract fuel from the closed loop areas (low throttle around 50mph for med trim and higher for high) and reset the ecu, your trims should stay higher. Or you can just unplug the narrowbands and your trims will all stay at 100.

Oh- you will have to do some driving in those ranges to get the fuel trims to change.

[x2xtreme360]

Or turn down the fuel pressure to what it's supposed to be.

Steve

Why? Why is it wrong to have higher fuel pressure? Why is it wrong to use an AFPR to get more out of your injectors?

[Chris@Rvengeperformance]

honesty if your instantaneous o2 trim doesn't peg at 32 or 120 then you are okay. If it is between there the ecu is still able to trim to stoic. I just aim to get the instantaneous trim in the 70s or higher.

[DrGonzo]

Because it screws up your fuel trims and pumps flow less volume at higher pressure. So you won't max out the injectors so soon with more pressure but you'll get less overall due to the limitation with the pump. Plus it adds an extra variable to the tuning, which isn't needed.
Besides TT injectors are good for about 400 ish horses at stock pressure which is more than you'll get out of a 10 to 1 CR motor on pump fuel before you run into knock.

Steve

Fuel Pump is a Walbro that is hotwired. It can handle the pressure. Flow is not a problem as all fuel lines have been upgraded to -6an lines/fittings. Flow and pressure are directly collated. You cannot have one without the other as long as the fuel has a place to go I.E. the FPR is allowing fuel to return to the tank.

So my O2 trims look good so I guess I should just reset the ecu and see how the fuel trims react to the new settings. So overall I should not worry about the fuel trims as long as the O2 trims are still within range.