ok so i jsut got a 93 240sx with an rb25det s1 in it. got everything put together and when i start it up it idles about 1500 for a few seconds then goes up to about 2500-3000 and stays there. ive tried adjusting the tps/cas/idle control valve thingy. nothing has really made that big of a difference. it has stock turbo, hard piping, isis intake manifold and tb spacer. the car drives fine it just idles wayyyy to high. what can be causing this??? and also theres only 1 plug connected on the tps. do both have to be hooked up in a manual car? any suggestions or ideas will be greatly appreciated, thanks

 

check for vacuum leaks

 

this.

and clean/check your IACV

 

+1 juan

 

check the voltage on the tps should be .45 i believe

 

could coolant temp sensor do this?

 

redacted

 

Well I'm pretty sure its not a vaccum/boost leak. I'm 99% sure its something electrical. And also I noticed something weird...my rb25det ecu doesn't have the diagnostic led and adjustment knob thing in it. It has the solder points for them but they aren't in there...and I don't think they ever have. Maybe that has something to do with it because I know that knob is supposed to help adjust the idle. And also what's the deal with my tps wiring? There's the "main" plug on the front of it with nothing going to it...and then like a pigtail coming off of it that is connected. Is this normal for an rb swap?

 

Just take out and clean the IACV first. It's easy, and if it works you won't have to start chasing down electical problems.

 

When's the last time you pulled an IACV on an RB25 David? Right...


OP, double check that the throttle plate is fully closed and that the throttle cable can fully extend. I had an SR that the throttle was being held open slightly and it took me forever to figure out why it was idling so high. Make sure the screw behind the throttle plate allows it to close all the way as well.