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Most of the time, when coming to a stop the motor begins to idle down and then hunts for a second, and then dies. If I open the throttle a small amount before stopping, the car will typically idle down correctly. The process doesn't start until I reach about 10 mph.
Also, how can I set the motor to run at higher rpm when neutral when vehicle speed is >5 mph? Such that the power steering doesn't bog the motor down when turning at lower speed.
Most likely the IAC settings. You may only need to change one item to correct this, possibility a couple.
First is to be sure that on a warm idle with no other loads on (fan, A/C, backlight heater, ...) the IAC steps are between 5 & 10. If they are higher then open the throttle stop screw on the TBI until they are in that range. Can use the WUD to observe the steps along with the 'idle' indicator light.
The reason to keep an eye on the idle indicator is that as you opent he TB screw the ECM will thnk that the driver is pressing on the gas pedal and drop out of idle mode. If this happens then shut off the engine, wait 10 seconds, restart, and let engine idle for a minute before continuing.
Once the IAC stesp are in the 5 - 10 range the other issues may be corrected. Drive it for a bit and see how it is. If the idle still dips low then increase the values in the "IAC - Minimum Idle Steps" table. The values here are the target idle steps. From a data log you can look at how many steps the IAC is at for idling at various engine temeratures. Then use thsoe value plus 10 steps or so for this table.
For the idle while slowly moving this is under control of the throttle follower (TF). Look at the "IAC - TF Min Steps" and the "IAC - TF Decay MPH Breakpoints" values. Probably want to lower the Low value of the breakpoint table to 2 MPH or so. Can then control the engine speed via the TF Min Steps value.
Be sure to set the IAC steps at idle to 5 - 10 before making any other changes. Every thing concerning the IAC is based on where the IAC steps are during idle.
Winter happened and I did not work on the tune at all. I've reviewed a datalog from today and it seems like I am mostly between 5-10 iac counts, but I did find a time when the vehicle was idling with 0 counts. Does that mean I need correction as well?
I started tuning with the wide band again today, so I turned off closed loop. In doing so, the problem was cured. This leads me to believe the issue is related to closed loop.
Good possibility that it is. This is difficult to diagnose long distance. Some items that I have found that can cure this is to set open loop decel on. Then run the VE tables during decel a tad on the rich side. This prevents the lean surges from setting in.
It is one area that really should not be run at stoich.
The other item is that the idle itself may be too lean. This can be adjusted separately via the idle O2 window values (lean, mean, and rich).
Once you are done with the open loop WB tuning we can re-visit this.
Should you be setting the idle stop screw in OL or CL? I just switched back to closed loop and had to readjust.
Whichever mode the ECM is being run in. At the same time if you force open loop just for some WOT AFR learning and observations that I wouldn't bother resetting the throttle blades.
