Does anyone know which box I need to check to monitor the Idle Speed Control duty cycle? In an older version which I don't have anymore it was designated as ? or ???.

 

No RX-7 PFC owner should still be using FC-Edit in 2026! Get a modern DL-340XB interface with its original software, and you'll have no problem locating the ISCV value. FC-Edit/ Datalogit still have lots of software bugs which their team has never managed to correct (or did any minimal effort to correct) in all these years. FC-Edit still shows RX-7 ISCV as '???' and it is NOT displayed as a percentage value. FC-Edit is also known to read wrong data from some PFC memory locations and will also write wrong data (without any warning) which can result in havoc on your ECU.

Note that street tuning using FC-Edit without utilizing FC-Tweak tuning software will result in a very poor tune, since FC-Edit does not correct for the lag time of the wideband channel (time taken for the exhaust gas to reach the location of the WBO2 sensor) and will accumulate most of the averaged logged AFR readings on the wrong map cells.


DL-340XB realtime data monitoring

 

Thank you for the reply Xavier. I actually have a registered version of FC Tweak and have found it to be amazing. I do not have Autotune yet but I am planning on adding it. Because we have recently made a move to another state my car has been sidelined due to other priorities. I now have the time and am in the process of getting my car back in order.

I was experiencing some fluctuation in my idle speed and had wanted to look at the ISC duty cycle. I remember the ISC was designated as ??? on the monitor screen but my newer version of FC Edit doesn't list that so that's why I asked.

Your new interface does look appealing. You've invested a lot of time and expertise in keeping the old PFC platform current.

 

Hi, since FC-Edit is a universal software is can sometimes 'lock on' to the wrong car model, show the wrong sensors list, and mess up some important stuff, as one can clearly see it's doing from your FC-Edit's screenshot.
Yes, it's just another one of those issues on which one wastes more time in trying to get the software work than in actually using it.
Anyway, to bring the old ??? (ISC) parameter on the monitor list, first load an RX7 dat file so that it re-adjusts its sensor parameters to the correct PFC model. Then you should be able to monitor ???(2) (range 0-1000).
Adjust the AAS screw to get ???(2) in the range 150 to 350 at idle (=15 -> 35%). If you still get unstable idle or see the ISCV values hit zero even with the AAS fully closed, redo the idle learning procedure as per Apexi user manual.
Hope this helps.

 

Thank you Xavier. I will try that.

 

Thank you again for the response Xavier.

The problem I have been trying to solve was a pulsating idle. Idle would pulsate between 1000 and 1500 rpm before finally settling down to 1100 rpm where I wanted it. Engine is a half bridgeport and I have been able to achieve a steady 1100 rpm idle in the past. So I removed the throttle body and adjusted both primary and secondary throttle plates to be nearly closed. Thought I might have a vacuum leak which was defeating the operation of the ISC valve. Opened the TAS slightly and adjusted the AAS and was able to again achieve a 1100 rpm idle with no surging. After setting up my logging function I was able capture ???(2) values. Values seem a little high, average is around 600 at idle. I'll try closing the air adjustment down and see if that helps and log again. What does it mean if the ISC values are higher than 350 but still less than 1000. Is it still controlling the idle?