CMKWAN79

Hi, may i ask anyone can help give some advice regarding my Mazda RX-8. Car condition - run normal just a bit slow to start up the engine (maybe low compression).
I had an engine light 'on' and check with OBD reader and the fault code was P2259- AIR System Control "B" Circuit Low (Generic - Powertrain).
I had bought a new air valve & changed the 3rd (lowest) air valve which near the throttle there but the light still "ON" with the same fault code.
Is that I miss-out any step or changed the wrong valve or any other parts need to be changed?
Appreciate if anyone could help???

NotAPreppie

Did you clear the code and it came back? If so, here are a couple of things to keep in mind.

1) Mazda spec top/middle/bottom positions but the position can be arbitrary. The important detail is that a given electrical connector is matched to the correct vacuum actuator. So, the AIR actuator could be attached to the top solenoid and it should work as long as the correct wires are attached to the same solenoid. Trace the vacuum hoses from actuator to solenoid to verify this.

2) It could be that the connector at the solenoid damaged or not making good contact. I can't find the threads anymore but one person noted that their connector had a bit of corrosion and another had to slightly tweak the conductors in the connector to ensure reliable contact.

3) It's possible (though unlikely) that you got a bad solenoid out of the box. You can test the solenoid itself if you have a 12V battery and a Mityvac hand pump. Use the instructions at the bottom of this page.

4) You can get these solenoids cheaper here.

Here's the FSM page on P2259
DTC P2259

CMKWAN79

Thanks buddy (NotAPreppie) for the reply

Yes, I did clear it by disconnect the battery. (Is that need t deleted by OBD?

1) I double check the position with my friend RX-8, is matching with the colour as well. You mean confirm which air valve by searching the one that attached to the vacuum hose?

2) Checked, in good form. Will double check again when free.

3) Tested the valve, in good form.

So the final answer from the technician is engine low compression, so warning light "on" affecting it and come out this P2259 code. Wanna make sure is that reals because rebuilt this engine not cheap at all. Worry money spent but problem din't gone.

And my brake also got a bit problem. When I brake continuously more than 2times for the same stopping, the brake will become harder. The more time I brake, the harder it get. Brake about 5 times for the same stop, you won't able to step it anymore because it become harden and at this time, brake are almost lost. But when I start forwarding for about 2 second, then the brake will lossen up and back to normal. The routine is same like this for every stop. Can't keep step on it for more than 3 times in 1 stop.

My technician said the engine vacuum return slow affecting the brake become harden. May i ask any of you experience this before?
Is that I need to change my brake booster pump or rebuilt my engine in order to get rid of this 2 issues?

Or that why my engine light still "on" even I changed the solenoid??

Pls help....

BigCajun

iTrader: (1)

For hard brakes, your brake booster check valve could be bad.
Those are easy and cheap to replace, it's worth a shot.

Loki

iTrader: (1)

Unless the technician has performed a compression test, he can't conclude anything and is making things up at this point.

Go through the proper diagnosis steps at the link above and come back if none of them help.

For the brake, yes it sounds like a vacuum problem. Test the check valve as stated above and test the brake booster itself. Proper steps for that are at the above link also, on another page. That's literally the book Mazda wrote for technicians to follow, so if your technician isn't following it, he is wasting your time and money.