I have a b16a2 swap in my 96 EK coupe.

Anyways I have a couple of mods and up until recently started having an idle issue.

First of all my coolant temp sensor is getting replaced because my temp gauge is taking forever to get to normal temp my car is always cold.

Anyways the car will idle high which is normal for a cold car but then it starts hopping. It will go from like 1500rpm to 2k rpm and sometimes it will be from 1000-1500rpm.

It hops between like 500rpms...

Also when the car gets heated up and its around a couple ticks under half way in the temp gauge the car idles right under 1krpm and is perfect....

What could be causing this?

It started happening when I changed from a p73 jdm ecu to a p06 chipped ecu.

 

Check your FITV(fast idle thermo valve). I would also clean the IACV on the back of the intake manifold just for good measure(never hurts). After cleaning IACV you'll probably need to bleed the coolant lines to get any air out... But start with the FITV, also, any codes? If so post those. Goodluck!

 

the taking long to heat up could be due to the termostat not closing all the way the other problem is probably due to the fitv

 

Yes, good thought, completey forgot about that...definitely replace the thermostat, even if that's not it, they're only like 3-5 bucks unless you get a spoon or a mugen thermostat.

 

My mechanic recommended changing the Coolant Temp Sensor, should I change the thermostat aswell?

 

Yes, its a thermostat and all it does is open at a certain temperature when the coolant reaches that temp to allow the coolant to flow into the engine. The coolant temp sensor is a two wire sensor located below the distributor, which controls when the fan cuts on and also controls your temperatre guage in your instrument panel. Replace thermostat first since its the cheapest of the two, and if that fixes the heating problem then there you go and proceed to check the FITV. If the thermostat doesn't fix it then you only "wasted" about 5 bucks...I think it will fix it though.

 

Thanks

I already bought a coolant temp sensor and im gonna get a thermostat and replace both tomorrow. I hope it solves the problem.

Also the IACV was cleaned about two months ago when I installed my skunk2 intake manifold.

If the thermostat/coolant sensor dont work im gonna check the FITV.

Thanks for the input guys.

 

No problem. Let us know what happens... Remember, you will more than likely have to bleed the air out of the coolant lines. Good luck!

 

Ok so I go to change the thermostat. Low and behold I didn't even have a thermostat... I got a new one and replaced it.

However now the weird idle seems to be happening all the time...

Its only when im at a complete stop. If I put it in neutral while driving its fine. Now its throwing a CEL aswell.