So i have a 97 civic with a jdm D16A & the crank sensor has been jumped at the ecu. Got car out of shop in march for the motor swap and she ran good for around 3 weeks but rpms would dip almost to 100 when clutch pedal was pressed in coming to a stop. Then CEL for iacv so took old one off and replaced it with brand new one. Took throttle body off cleaned all ports & intake best i could but still P0505. Was a valcum leak from pcv so new one valcum leak gone. Car will hunt idle from time to time & rpms dont drop if iacv is unplugged but jump to 1500rpm when reconnected then @ 1700-2000 motor would jerk / sputter. Its like not enough fuel or air , rpms will go up & down when its doing this. Im stumped and it seems to only be getting worse & doing it more often now. Oh btw the tps checks out good & iacv shows 14.3 on multimeter with key in position II & car running. Please Help!

 

Still sounds like a vacuum leak. Any reason you didn't take it back to the shop when you started having issues so soon after the swap?

 

The shop was going to charge me $75/hr to figure it out. If you cover the little port inside the throttle body while its idling it will go dead. Before i replaced the pcv it would just idle down really low. Ive gotta be on the right track making some kind of progress with this thing atleast i hope. Could it be the ecu controlling the ivac? Are the rpms suppose to drop to 600 with the a/c on?

 

when i tried to bleed the coolant system the fan would kick on & coolant level would drop so topped it off & small bubbles over & over its like they never end. Also just installed a crv cluster & temp needle seems to be a little higher when running than the stock civic gauge needle. Maybe bad temp sensor?

 

Resistance test the ECT sensor, though the constant bubbles in the coolant and the overheating may indicate a blown head gasket.

 

The temp gauge sits halfway between hot & cold once the motor is warm.

 

The Civic temp gauge generally reads ~1/3 (below 1/2) when the engine is fully warmed up.

 

sounds like tps! maybe my 93 civic ex with a d16a, did the same thing between 1500 and 2000 rpms, rpms could vary test before replacing though to save money