Solenoids
 

Yeah.. I don't like that hugeass array of solenoids right behind the alternator.. Which one does what? I've removed pretty much everything not essential to engine operation, so I figure I can get rid of a few of them (such as EGR at least).

-Tesla

First one is the relief solenoid valve. It sends vacuum to the ACV to vent the air pump output.

Second one is the EGR solenoid valve. The ECU uses this solenoid to send vacuum to the EGR valve at appropriate RPM.

Third one is the switching solenoid valve. It is used to signal the ACV (with vacuum) to switch the air pump output from the exhaust ports to the Cat.

Fourth one is the pressure regulator control solenoid valve. It is used to force the fuel pressure regulator to high pressure mode for a short period of time (warm start) by venting engine vacuum to it.

The black valve hanging in the middle is the Rotary equivalent of a PCV valve.

If you have any questions, post a reply.

Irv, Keith's dad :cool:

I checked..it seems you mean front to back.. So, since I have removed the ACV and EGR, I can delete solenoids # 1, 2, and 3? Is there something I need to do to fool the ECU into thinking #2 is still there?

Do I really need solenoid 4?

-Tesla

Hey Tesla,

We're talkin' pre-98 ECU here. Believe me, this ECU wouldn't know the difference if you hooked it up to a potato! :D :D

As for the pressure regulator solenoid, it only works on hot starts. Apparently Mazda engineers thought that engine heat could cause vaporization in the fuel lines, so full pressure is needed even at idle for a short time to condense the vapors. Is this a problem on your car? :confused: If you want to test how it runs without this vacuum cut, take a ride for at least 1/2 hour, turn off your engine, connect the fuel pressure regulator directly to a vacuum port, let the car sit for about 10 minutes with the hood closed, and start 'er up. If it idles/runs nice and smooth for at least 50 seconds after it starts, you can do away with this solenoid. If it doesn't, you need it. Of course, I would try this test on the hottest day possible. Anyway, it's your call.

Irv, Keith's dad :cool:

Just want to make sure... I should just cap off all those open ended hoses after I remove the solenoids, right?

-Tesla