What would cause the engine to rev and down rapidly. I was told its my idle control valve. But i have taken the idle control off and cleaned it and even replaced it. It keeps coming back. Would the EGR Valve or the fuel pressure regulator have anything to do with it. Also looking for performance parts for a d16z6 engine , Intake manifold , Turbo Pipes to fit engine in a crx hf engine bay. Present engine having probs is a d15b6 swapping soon to the d16z6. Going to rebuild the d15b6 , So any ideas to replace the original parts on the d15b6 let me know.

 

My idle used to bounce on my B16A, my IAC was throwing a code and my O2s were both wired to 1 sensor (Bought it like that). BUT my throttle cable was too tight so it was pulling on the throttle, when i fixed the throttle cable it idled rock solid, it just bounced if i reved it and held it in one spot. Something to check that if it works might not totally fix the problem but for me it made it no longer annoying.

 

if u have the d16z6 and ur ruining the z6 intake manifold and throttle body. then the problem lies with ur fast idel thermo valve (FITV) which gets stuck open at start up and makes ur idel surge up and down . gets annoying, just happen to me and i fixed it, how to see if this is ur problem which i say it is, take off ur intake tube and start ur car, put ur finger on the bottome hole inside the tb which is the (FITV) if that has sucktion at idel then thats whats causing the problem, i just blocked it off with a thick peice of rubber and by passed it and fixed my idel surge, i can give u more detail if u hit me up, hope it fixed ur problem.. good luck

 

I agree... It's your FITV

 

Could be ur idle screw. When I finished my swap it surged up and down. I tightened the idle screw down and it stopped.

 

if you live in canada or northern states in the U.S. then the idle surging isnt even consistent annually, its seasonal.

For example I had a major problem after doing mpfi swap with the idle surging from 900-1500 rpm and it was annoying as hell. I bled the coolant of any air, replaced EACV, yadayadyada and nothing. Then when it got a little warmer such as spring time the surging died down a bit and was 100% eliminated by replacing "what looks like good condition" vacuum wire with new stuff.
Its showing its ugly face again now as its -10*C in my area now but the smallest thing can solve the issue to, just a matter of lots of trouble shooting

common idle surgin reasons
1.) insufficient coolant level
2.) excess air in the coolant system
3.) EACV valve malfunction
4.) vacuum leak from old vacuum lines
5.) "plunger" in the coolant related item underneath throttle bodies like on the z6 thats stuck
6.) and many other things that ppl can name from experience

 

no for now im still running the d15b6 until i have everything i want for the d16z6 like turbo or supercharger undecided, I want it to be a complete performance engine. when i swap that one in then im going to rebuild the d15b6 again turn it into a complete performance engine then ill have to decide what to do with it lol

 

Hey,
Could you please explain/email me how to fix the revving up problem in detail..... I'm a girl, so I don't have as much experience with cars. Thanks!

 

Was a bad four wire O2 Sensor on my buddys car...