I tried to recirc my Greddy Type-S, but I can't loosen it more than 2 turns without the car eventually going into limp-mode. It takes about 15 minutes of hard driving, then the SES light turns on. I even installed a new stock MAF on my 2001 SE, but the voltage at idle is still ~1.2V according to the SAFC2. A normal MAF voltage at idle is 1.3V-1.7V. Also, the MAF is 12" away from the recirc fitting on the intake pipe.

Could it be a bad ECU connection that's causing the low MAF voltage at idle and the SES light? The FSM says the SES light can only be caused by an excessively low MAF voltage, which I think is from the turbulence of the recirculated air. If I fixed the low voltage, would I be able to loosen the BOV more? (to get rid of the compressor surge)

Thanks for everyone's help!

My initial guess is that you have a big vacuum leak.

did you use the Jay Whitely instructions? I couldn't get mine right until I followed these:

GUARANTEE that the following will solve your compressor durge problems. I have done this numerous times on many cars and it wroks flawlessly.

1. Take the BOV apart by removing the allen head screws. There are 2 springs inside....a small one (inner) and a larger one (outer).

2. Remove the outer one and set it aside.

3. Reassemble the BOV with only the smaller spring inside.

4. Wrap the adjustment screw with an adequate amount of Teflon tape.

5. Rent ot buy a hand held vacuum pump. Attach the vacuum hose from the pump to the upper nipple of the BOV.

6. Start squeezing the pump and note at what vacuum level the plunger BEGINS to lift from its seat.

7. The goal here is to get it to BEGIN opening at 10 inHg of vacuum. If it starts to open at 5 inHg, then tighten the screw down and retest. Conversely, if it opens at 20 inHg, loosen the screw and retest.

8. Continue to adjust and test until you get a reading of close to 10inHg as the BEGINNING opening point. With this setting, the valve will be fully open at around 15-18 inHg of vacuum.

9. Setting it this way requires you to recirculate the BOV, as the valve will be open at idle. Remember your engine will make about 17-22 inHg of vacuum at idle, which is more than enough to open the valve.

10. If you cannot get the adjustments right using this method, then repeat using the larger spring instead. I have always had success with only the small spring in the BOV.

11. What you have essentially done here is make it require less vacuum force to open the valve. This will decrease the likelihood of compressor surge and the valve will open sooner and be more responsive.

12. If you do not recirc, then you will need to set the valve to begin opening at about 25 inHg. This setting will be less responsive and CAN result in compressor surge.

13. As a test to the validity of this process, hook up the vacuum pump to a stock DET BOV and see what amount of vacuum is required to make it start to open.

^^^
I used those instructions and it worked great. Where is your recirc at on your inlet pipe?

yeah one big issue is if the recirc isn't aimed at the compressor inlet it could bounce off the pipe and hit the MAF in reverse, which makes it say WTF????

Did that to me a few times till I learned this.