I noticed this problem ever since my engine replacement. My engine surges on idle sometimes. The rpm dips down to about 800 and then up to 1300 and keeps going up and down between those ranges. When I turn on the headlights or another load to the engine, the rpm holds steady at around 1200-1300. Once I let go of the clutch slightly while still holding the break, and then slowly press down on the clutch to ease the load of the engine off, the rpm sometimes holds steady too. I suspect it might have something to do with my power FC settings. I think it might be trying to control my engine idle rpm but has a kink in it somewhere. anyone in the greater vancouver area who knows any shops that tunes power FC units? =3

 

As with some controling electronics, they can have a narrow range of operation.
These you have to HELP like adjusting some idle parameters.
Have you ever done any idle adjustments on carb or other FI cars?

Just like with EBCs, you have to help them!

 

I have never adjusted an aftermarket ECU parameter before. and I only adjusted some carburators during school. The power FC handheld unit lets me set some parameters but its in japanese and I don't understand what some of the parameters do such as "A.E off, and A/C on"

 

this is a US spec car? did you cut/depin the wires that the instructions mention when installing? Did you do the idle learning procedure in the instructions?

 

do the idle learn proceedures as arghx mentioned this should help

 

That is a very lame excuse. You can download the PFC/RX-7 manual on the Apexi website and the above stickies also contain directions to get it.

The rest is common auto mechanic experience that you need to learn.
Most libraries contain such books which you may read, or maybe not.

The two basics that normally affect idle most of the time: air flow and fuel.
The commander can be used for fuel and the base idle air flow.
But since the base idle air flow is not working (fluctuating idle speed), you have to manually help it by adjusting the AAS or TAS.

You need to download the field service manual and study section F which is the engine control systems.

If you had searced this forum, you would have discovered that your problem is very common with newbs that are not car experienced. And you would have learned somethings.

You need to get motivated!