Series 1 rb25det cold idle issue

[rayaapp2]

One of my RB25det's acts funny. Greddy intake, stock turbo, Q45 TB, APEXi PFC, and all pretty much stock except the Z32 TT MAF that was grafted on.

Ive tried setting the temperature settings, Ive checked for vacuum leaks, Ive unplugged the air regulator, closed off the IAC bypass screw, closed the throttle plate all the way, and gone into the Power FC I have and set the idle as LOW as I can go(500rpms).

 

When the engine is cold it barely idles at 500.

When the engine fully warmed up it idles at 1000-1100 rpms.

 

This engine has no idle kickups like AC or P/S pressure switch.

 

I thought I had a faulty Air Regulator, but I unplugged it and used hose crimp pliers on the feed tube. I also crimped the PCV hose.

All that is left is the IAC I suppose, unless there is an internal defect on the throttle plate that I havent checked out yet.

I thought it might be the MAF settings but it only affects the engine at full warm up so I am looking over the temperature related stuff.

Its weird that it idles fine when its stone cold and then warms up and cannot get below 1000rpms.

None of my other RB25det have this issue and I acquired the car with this issue. I did go through the entire wiring harness for the FI and checked everything which took an entire saturday thanks to whomever decided to cut the boost control solenoid wires back near the ECU. So I ended up stripping and checking all the wiring connections since I found several other similar foul ups just to be sure my harness is good to go.

 

 

[David GArcia]

Have you tried to disassemble the iac valve and clean it with some carb cleaner? and check if your power fc setting and find if your using the correct setting for the z32 maf. Now check the maf voltage at idle you can actually lower the percentage of the voltage through settings. Change the percentage of the given volts that are given at idle. Lower it by .5% at a time until you get a desired idle. Not all mafs read the same voltage even when they are the same maf for example compare a couple z32 mafs and youll find that the signal voltage at idle is different even if its at the same rpm.

 

 

now check if you have a smooth acceleration.