i have a b16a in my 89 crx hf . well when i start it up it will rev to 2300rpm then when it warms up it will go to 1100rpm to 700rpm up and down . i check the vacuum lines to . when i drive it for a lil and i get on it like around 4500rpm it will go and stop like it spark or not getting enough gas im not sure .no check engine light comes on and the ecu is not flashing .you can email me at ehondab16a@netscape.net thankyou and have fun !

 

check your TPS, throttle position sensor.

 

that or i know on my b16, there's a bolt on the top of my throttle body that come out, u can hear it whistle if this is the case, and u'll be able to locate it, if this screw came out just plug it up or get a replacement from honda for $8 lol. that caused my idle to go b/t 700 and 1200 RPM

 

how do i check the TPS what im i looking for ? thankyou for your reply

 

make sure its hooked up correctly

 

If the check engine light comes on and the ecu does not flash try another ecu. Idle problem could be the FITV (fast idle thermo valve).

 

thankyou for the reply .yea my engine it not on or ecu is not flashing just when you first start the car but thats ok .

 

fast idle control valve its on the bottom of the throttle body take it off and just run coolant lines to the idle control valve which is on the back of the intake manifold and just cap up the bottom of the throttle body i got a piece of metal and drilled holes in it at the same location as fast idle control valve bolts were and capped it off supposedly this will also give you maybe 1 hp because then hot coolant isnt gon through the throttle body which = lower intake temps and it fixed my car

 

try hooking up to a 90-91 Ls ecu but dont drive it Just let it run and see if it does the same thing if it does i will tell you what to do