S5 JDM TII motor, trying to tune, but no BAC adjustment...Help
 

I am trying to get my rebuild to run right and the Mazda manual says to adjust the idle with the BAC valve... but my JDM motor has no screw in where there is supposed to be a screw?! Am I missing something? Thanks

EDIT: Side note, where is the Exhaust temp overheat sensor on my S5 TII?

TTT already!

I'm having the same problem with my Jspec andjustments...

Wow, no gurus....

I had problems with the BAC too! I decided to block it off and adjust idle via the screw on the TB. =p

yeah my jdm s4 has the same damn thing! no screw to adjust idle speed. i am probably just going to swap my old bac on. i also noticed injector clips are different, no air bypass solenoid, one less aux air line coming off intercooler, no oil thermo sensor, and no egr on lower intake manifold and accompaning egr switch/check valve thingy. also mine runs rich as shit right now! going to investigate further tomorrow. i dont thing the air supply valve doesnt have and adjustment screw, and i kinda figure may need to adjust tps, dashpot, and idle mixture dashpot too. kinda sucks!!!

There isn't one. I have no idea why, but the only way I've found to adjust my idle is to adjust the primary throttle stop screw. You need to remove the intercooler to get to it, so I made a PVC crossover pipe so I can idle the engine without it.

Under the carpet under the passenger's seat.

Thats a damn good idea. It solves so many PIA problems for me you have no idea. Thanks!

Huh, I can get to that primary adjustment with a long flathead...

i found that i too could reach the primary, still working the bugs out.

You must be thinking of another screw, probably the TPS adjustment. The primary throttle stop screw is under the intercooler and points upwards, so unless you're poking that screwdriver through the intercooler, there's no way to adjust it without removing the intercooler first.

jason you can adjust the screw with a long flathead screwdriver. and yeah, the jspec engines didnt have a BAC adjustment screw for some odd reason so you will have to find other means of adjusting your idle as jason did.

what exactly do you mean by this? details?

I have a pipe that replaces the intercooler made from 50mm PVC pipe and bends. The engine can idle and I can get to the TB. :)

My adjustment screw for the throttle stop points out at about a 45 degree angle towrad the passenger side of the car, it does somewhat point up toward the intercooler but not enough...maybe that's why my car won't idle...

The screw NZ was talking about has a jamnut on it that is 8mm wrench size and the screw itself is appox 1/4 inch long and is TINY in size.

The jamnut has to be loosened to adjust the screw. If the screw can be turned without loosening the jamnut.....then the jamnut isn't on right/tight. He's not talking about the fast idle screw or the fast idle cam adjust screw.

The PVC pipe is just that. Go to HomeDepot and buy about three feet of PVC pipe of the right diameter of your intercooler intake and outlet hoses. Cut the pipe to fit b/t the intercooler inlet hose and the intercooler outlet hose. I cut the PVC into two sections and joined the two together using a PVC 90 degree elbow. The PVC takes the place of the intercooler which you'll lay to the side while adjusting the idle.

I can't find that screw for the life of me. I have no idea what it looks like or where it is.

HAILERS, the jap engines had BAC's that have NO adjustment screw.

I was writing in reference to what NZ convertible said. I was talking about the throttle stop screw and where it is located. I take everyones word the JSPEC don't have a bac screw.

<3

I am beginning to think that my TII ECU is dookie.

Well, my boost gauge showed zero vaccuum when starting and *barely running,* check the gauge and it is OK, then I removed the upper intake mani to check for vaccuum leaks low and behold there, sitting on the LIM is one of the injector grommets, imagine that, I somehow managed to not get one of the injector grommets in there, causing a massive vaccuum leak and causing the pressure sensor to see nothing...etc...I am sure that was my problem but now it is snowing so f*** the car for today!

FIirst of all, I blocked off the bac and I adjust my idle with the throttle cable. There are 2 nuts on it. Anyways where did you connect the boost guage? You should try to connect it to the bottom nipple(IIRC). on the UIM..