i have a b16a jdm motor swap into a 88 honda civic hb. my idle on the car has some how drop to 500 and sometimes lower to 200. when i start my car in the morning or when going somewhere, it idles fine at 800 to 900 rpm. but when driving, the rpm drops right back down to 500 or 300 rpm, sometimes lower. i have check everything i can with this motor and there is nothing that i can do to fix the problem. my throttle cable is tight and set correctly where it idles nicely when started. now it just scares me that the motor might die out on me. if anyone knows about this problem or has any information or experiences. please help me out. thanks my fellow racers.

 

First try unplugging something vital like the coolant temperature sensor on the back of the block. This will cause a Check Engine light and the computer will go into Backup mode, operating in open loop. At this point, if the idle is all f*cked up because of an erroneous sensor reading, the car should idle and run fine (besides the Check Engine and Backup mode). After that just reset the ECU and we can work from there...

P.S. I take no credit for this idea; you can thank Da Man who calls himself fixhondas for this one...

 

let me try this and i'll get back to you. thanks man.