GreenMachine

MY 84 GSL-SE Idles at around 6700 RPM when the secondaries are hooked up but if i unhook them it idles regularly. And i have no idea what controls the secondaries for opening and closing. Please help

calpatriot

See the Factory Service Manual link in the FAQ section.

mazdaverx713b

iTrader: (91)

the 84 SE does not have secondary injectors. it only has two 680cc injectors. a 6700rpm idle would mean a stuck shaft or butterfly in the throttle body or a bent or kinked or lodged accelerator cable or bracket. inspect the throttle body for bent parts around the throttle shafts and inspect the idle stop screw and the cable mount.

GreenMachine

what is that plunger thing on the side then that opens and closes those two butterflies?

calpatriot

The butterflies are variously called the 'double throttle', or the 'No. 2' throttle. They are supposed to be open during normal operation (after warm up). Under cold (pre warm up) conditions, they are supposed to be closed at idle, and then open slowly after application of heavy throttle. This is supposed to keep the engine from faltering during heavy/sudden application of throttle when the engine is cold.

There is a thermo valve on the rear of the throttle body. It receives coolant via a hose coming from the left side of the throttle body. The valve allows vacuum to the hose leading to the diaphragm when the coolant is cold, and ambient air pressure to the diaphragm when the coolant is warmed up. The vacuum hose from the thermovalve runs forward under the right side of the throttle body, and through a delay valve. The vacuum holds the butterflies closed, until you give it throttle. The vacuum drops, but that drop reaches the diaphram after a delay determined by the delay valve, which is underneath the intake tube just right of the throttle body.

If is is not working, it usually is due to holes in the old, deteriorated diaphram, or failure of the thermovalve, or both.

Some people just wire the butterflies in the open position, and accept whatever drivability problems occur in cold ops. Others remove the butterflies altogether, under the assumption that even when open they provide a restriction to airflow, and in theory the engine should develop more power without them in the way.

If you live in a cold climate, you probably want it to work. I rebuilt my diaphragm, and replaced the thermovalve, 'cause I like my systems to work the way the designer intended, and mine is a daily driver that never sees a track.