Just got my new turbo installed this past weekend. Had to replace it due to the old one going bad in less then 100 miles. Its a SC52. The problem I'm having now is that it idle fine with the old turbo on but now ity won't idle lower then 1800rpm and if its reved up it won't cauch it self. Driving and accelorating are fine. Its all been tuned with an AME EMS. None of the settings were changed at all. Just replaced the turbo. Any idea what could be going on?

NOTE: Its a 99' Accord 4cyl. Build block, EMS as stated, 780cc inj. Aeromotive FPR, -6an fuel feed line from tank, 255lph fuel pump, 3" exhaust and down pipe. Greddy RS bov, Tial wastgate.

P.S. The IAC valve is un-hooked but that has never affeted it before. The idle holds steady it doesn't bounce. Thanks in advance for the help.

 

I think its your FITV (Fast Idle Temp Valve). Below is write up that might fix your problem.


This write up was written by XDEep (g2ic.com):

INFO: At room temperature, the wax in the enclosure is small enough so that the needle is pressed in by the spring loaded valve, thus letting in air through the ring-cap and increasing the idle. The needle sticks out 6mm. As the temperature of the coolant rises to about 150F, the wax expands and the needle eventually protrudes to about 11mm at around 220F. The force of the needle on the spring keeps the valve closed. If the ring-cap is loose, there is not enough force to keep the valve closed thus letting in air and raising the idle when not necessary. These are the steps needed to tighten the ring-cap:

1. The FITV is held in by three #10 bolts. Remove the bolts to release the valve from the manifold. You do not need to remove the two coolant lines unless you do not have enough room to do the next step.

2. The plate is held on with two #8 bolts. Remove the bolts to get the cap off. The plate will fall easily so be sure to catch it.

3. Now you have access to the cream colored ring-cap inside. What you want to do is tighten it. There are 2 slits along the ring. Unless you have a short screwdriver or tool that is 1" wide, you need to use two screwdrivers in unison to tighten it.

4. Reattach the plate and bolt the valve back on to finish the adjustment. If you removed the coolant lines, be sure to refill the coolant and bleed the system.

Q&A:
Q. so this would cause the idle to be higher then normal, when not needed.. hummmm...

A. ya the wax would not expand, letting extra air in after its warmed up. however, i dont think there is a sensor that lets the ecu know exactly what is letting that air in. now since the iacv is doing its business and idle speed is set, i would think a readjusted idle screw would mask it. hmm..
ok when cold the ecu runs in open loop (stored maps) and the FIV lets in more air. when warm the rpms drop and the o2 sensor is used in closed loop mode and the ecu tries to maintain target idle. but if the FIV is not fully closed the idle is raised. does the ecu correct it down? does it correct it down stable or intermittently like a pcv leak?

 

Thanks for the help. I found after trial and error that I had to adjust the TP settings and the coolant idle settings to get it were I wanted it. Idles fine now and revs down on its owen with out stalling either.