Is the IACV-AAC plunger supposed to be able to slide freely back and forth when its solonoid isn't energized?
Should the base idle speed be set with only the TPS connector unplugged, or should the throttle position switch and IACV-ACC connectors also be unplugged?
Can the amount of RPM increase provided by the IACV-FICD be adjusted?
With this particular Nissan, do the throttle position sensor and IACV-AAC need a recalibration procedure involving the computer, or do I simply adjust the TPS for 0.5V with throttle closed?
1997 2.4L pickup idle controls
yes
throttle switch only
yes
after you aquire the proper voltage setting on your tps before starting the vehicle back up cycle your key off for 10 secs then on for five then off for 10 secs repeat three times. this resets the self learn values in most OBDII nissans.
Technically the tps is now suppose to be set using the throttle switch an ohm meter and feeler guages. nissan had a bulliten to disregard the info in the service manual on setting it and use the procedure in the tsb. but honestly you can do it either way and aquire almost the same results.
throttle switch only
yes
after you aquire the proper voltage setting on your tps before starting the vehicle back up cycle your key off for 10 secs then on for five then off for 10 secs repeat three times. this resets the self learn values in most OBDII nissans.
Technically the tps is now suppose to be set using the throttle switch an ohm meter and feeler guages. nissan had a bulliten to disregard the info in the service manual on setting it and use the procedure in the tsb. but honestly you can do it either way and aquire almost the same results.
Thanks for the great information.
It turned out that I was completely wrong, and the TPS and throttle switch were fine.
I originally thought the switch was bad because it measured 39-80 ohms closed, even when removed, and when I shorted the connector pins for the switch the idle was completely smooth, even at 600 RPM. But when I tried this later the idle was again bad, and a brand new Hitachi switch also measured 70 ohms.
So I kept looking for vacuum leaks and bad connections, but then it was noticed that spark plug #4's boot occasionally arced 1/2" to the exhaust manifold heatshield. The boot looked perfectly fine, but the idle always smoothed out perfectly when the boot was rotated 180 degrees. The plug wires were Prestolite (original?), and the vehicle has only 56K miles on it.
I don't understand why the misfire never caused an OBD II code to be set and the MIL to come on because I thought that misfire was detected through variations in RPM, not by monitoring the sparks themselves.
It turned out that I was completely wrong, and the TPS and throttle switch were fine.
I originally thought the switch was bad because it measured 39-80 ohms closed, even when removed, and when I shorted the connector pins for the switch the idle was completely smooth, even at 600 RPM. But when I tried this later the idle was again bad, and a brand new Hitachi switch also measured 70 ohms.
So I kept looking for vacuum leaks and bad connections, but then it was noticed that spark plug #4's boot occasionally arced 1/2" to the exhaust manifold heatshield. The boot looked perfectly fine, but the idle always smoothed out perfectly when the boot was rotated 180 degrees. The plug wires were Prestolite (original?), and the vehicle has only 56K miles on it.
I don't understand why the misfire never caused an OBD II code to be set and the MIL to come on because I thought that misfire was detected through variations in RPM, not by monitoring the sparks themselves.