P0171 open loop

any you guys know what actually triggers the P0171 to go off in our PCMs?

Im doing some open loop stuff to save some gas and was wondering if its a certain afr that sets it off? I keep throwing it even though Im running a little rich even...

depending on what throws it I may just delete it from the PCM since I tune in open loop anyway...

P0171- system too lean

thanks
Jarred

2 consecutive diagnostic tests that fail.
Fail is determined by the pcm having the ltft at more than 16.4 IIRC.

In open loop, the pcm can remember fuel trims from when it has ran in closed. Be sure to clear any fuel trims before you switch to open loop.

Originally Posted by darkhorizon

In open loop, the pcm can remember fuel trims from when it has ran in closed. Be sure to clear any fuel trims before you switch to open loop.

by clear do you mean just reset them when I switch to open loop or do I have to do something in the closed loop section of the tune itself?

sorry just confused by what you mean by "clear" the trims...

There is a command you can send with powertuner using the powertuner scanner that says "clear fuel trims".

What about with HPtuners?