I have a 1990 JDM FC3S 13BT. Was idling very erratically so I replaced the BAC valve and now it runsmuch better but now has a new issue. Sometimesafter it is warm and I come to a stop it idles smoothly but when I apply anythrottle it bogs and dies down. When Ilift it returns to a smooth idle and repeat the process. Also if I turn the car off and restart it theissue will go away until the next stop, then sometimes does not happenagain. Also from the beginning the carhas had an erratic dip in it’s acceleration. At random points under load the motor’s pull drop in and out at mid tohigh RPM’s. Any thoughts are welcome.

 

 

You need to pull codes. Since your car is a JDM you'll likely have to use the S4 method.

http://fc3spro.com/TECH/HOWTO/ERRORC...KI/zerror.html

 

Very cool, I'll give that a shot and repost.

 

Use the 3 wire Green check connector near the lead coil. The LED test light uses two of these wires. One wire from the test light uses the Black/White wire while the other test light wire uses one of the remaining two wires (cannot remember which one specifically but you'll figure it out). And there is a single Orange wire in a Green check connector right near the other check connector. W/key to on this Orange wire might have to be grounded to pull codes (you'll find out one way or another if that is the case). And you use the error code list for the S5 and not the S4 as you're just using the S4 method to pull codes.

 

Should I use this one due to the year being 1990?

89-91 CPU Trouble Codes

 

This one didn't work as there is no engine light.

 

I don't think you'r getting my drift! Your car does not have the check engine light which is why it was suggested that you use the S4 method. Make sense. Did you look at the method for the S4? The light you use, an LED, takes the place of your missing CEL. Again, you use the S4 method to pull error codes and if you have any you use the S5 error code list to determine what is shows.

 

No, I'm crystal clear now. I read the instructions and plan to go buy the LED lights to make the diagnostic tool.

 

I built the tester and it displayed no error codes. Any suggestions?

 

Unplug the boost sensor and try pulling codes. If the disconnecting of the sensor gives you an error code then you know the code checker is properly being applied.

 

Will do.

 

Update:
Turns out the car has an Apexi ecu. I bought a commander for it and have solved the problem by adjusting injector duty. Currently I am researching how to best tune the ecu with the commander.