a/f at partial trottle/WOT

[roadboy]

hey, if anyone knows this let me know,
currently if im at partial throttle (25%-35% ect) my car will run rich to the point where its 10:1.idle and cruise are fine where its reading 14.7. i read that open loop starts at 69% throttle. could this be caused by my fpr? i dont have a afpr yet as i have a stock one.
im using a SAFCII to tune.

also heard that im not suppose to tune low throttle only high throttle.

currenty have installed:
550cc, walbro, lex afm

anyone know?

 

[Turbo Habanero]

This is normally caused by a Boost leak or a AFM problem

 

[Dan_Gyoba]

Idle is open loop, so it's based on the AFM signal pretty much alone, as is WOT.

Part throttle is closed loop, and so the ECU will trim fuel to maintain the 14.7:1 stoichiometric AFR. The two states are completely different.

10:1 is pretty rich. With the 550s and Walbro, you should get rid of the J tube restriction in the return fuel line, as this can cause fuel pressure to be too high, particularly at low RPM, and might account for some of the rich condition at idle. At WOT, the TCCS is pretty well known to run very rich.

 

[roadboy]

yea I already did the jtube restriction, just wondering if its caused by the stock fpr. And should I upgrade to one.

 

[jetjock]

Idle is closed loop. The OP states he's rich at partial throttle but doesn't define what he means. Is operation steady state? If so the system should be in fuel control.

 

[honeydew]

Stock FPR? With a Lexus upgrade? Hmm.

 

[3p141592654]

Closed loop is the norm as JJ says.

The decision to go open loop is not as simple as just the throttle position. Its mainly based on load and rpm, the actual cutover depends on both, but for rpm < 3600 48% load is the threshold. As rpm goes up, the threshold drops to 0% load at 7600 rpm.

There is typically a 3 second delay from when the load threshold is met before the ECU goes open loop. That three second delay is eliminated for a bunch of special cases such as rpm > 6000, large throttle opening (definition of large depends on rpm), large fuel enrichment request (from a 2d map of load and rpm) or high engine stress (computed from current high-temp ignition retard and knock retard values).

 

[roadboy]

Idle is closed loop. The OP states he's rich at partial throttle but doesn't define what he means. Is operation steady state? If so the system should be in fuel control.

i mean on my SAFCII the reading for throttle % is about 25%+, thats when my wideband is starting to go rich, this is from normal driving when shifting up a gear (shifting at 3500)