Low Throttle Tuning with just WB?

[LaminarFlow]

I'm installing a fuel pump and 720 injectors tomorrow. I've got the SAFC and Zietronix WB already, but not the pocketlogger. I've read the Tuning Guidelines. I heard it's not recommended to do the blue wire mod, so the SAFC does not see the O2 volts. Which shouldn't matter because I have the WB. According to the "no-logger" method of low throttle tuning, I drive at say, 2k rpm, and watch for the A/F ratio to cycle (which is the same thing as watching the O2 volts according to the guidelines). Once cycleling add clicks to the AFC until it stops, then back off -2%.

Yes, I'll get a logger eventually. But I want to get this installed now. Will this method work for the low trims?

[turbolarry]

According to the "no-logger" method of low throttle tuning, I drive at say, 2k rpm, and watch for the A/F ratio to cycle (which is the same thing as watching the O2 volts according to the guidelines). Once cycleling add clicks to the AFC until it stops, then back off -2%.


You lean it out (subtract "clicks") at the specific RPM point your trying to set till it stops cycling, then add 10%.
From; http://www.roadraceengineering.com/newafc.htm

Initial AFC Tuning (Low)
While in neutral, try revving the engine to the exact RPM settings on the AFC. Hold the RPM, and then start playing with the setting for that RPM. Listen to the exhaust. Start on the rich side, the engine will likely sound very "smooth". Slowly work your way lean, you'll start to hear misfires (popping sounds). A good point is probably where things just start to pop a little but are pretty close to "smooth" (rich). Watch the O2 sensor voltage or A/F ratio meter. Normally the voltage will swing back and forth between .2 and .8 volts at idle and part throttle cruising. . As you adjust leaner, the ECU will compensate back richer. Slowly click down leaner so that the LEDs do not come up. You will then see the O2 voltage come back up slowly. This is the ECU re adjusting. Keep going down until the ECU can no longer bring the A/F ratio back up to swinging in the middle LEDs (.2-.8v). From there richen that rpm point back up about 10 percent. That should put you pretty close to 0 to 5% fuel trim at the ECU.

Next repeat the same thing driving the car on the freeway. Hold the car at the rpm that you are going to set. Note what percentage you are beginning with and slowly go lower until the ECU can no longer richen things back up. Go richer about 10% more and compare that with the compensation percentage that you started with. You should be fairly close.

When you get things too far out of whack, you will most likely get a check engine light code for Fuel Trim. It just means that the ECU was trying to adjust things to get back between 0.2 and 0.8 volts and couldn't. Don't panic, this is normal. Try to figure out where you were too lean or rich and fix it up. Re-set the ECU and see if the code re-appears.


I've done 2g DSM's this way, but not Evo's. Let us know how it goes.

[LaminarFlow]

Cool.. thanks for the link Larry...

On a sort of side note, when Im parked and hold the RPMs at like 2k, the A/F tries to hold 14.7, but about every 2 seconds, it sounds like the exhaust burps. As a result, the A/F spikes, then quickly levels to 14.7. It looks like a heart EKG plot. I was thinking it was the free-flowing exhaust, but it is so consistant I'm thinking it has something to do with the ECU. Is this normal?