Spawn VII

ok i'm trying to find out what the function(s) of the boost sensor is (the one on the passenger side strut tower)

searched and only found this thread that had something on it....
https://www.rx7club.com/forum/showth...ensor+function

what happens if the boost sensor goes bad? what's affected? i suppose the sensor has something to do with fuel, since you install a FCD on it... anyone?

Scott 89t2

it controlls timming. which is very important on a turbo car.

Spawn VII

so if the sensor goes bad, what will happen to the timing compared to a good sensor?

...and nothing to do with fuel at all? what abou the fcd?

NZConvertible

On S4's controlling ignition timing seems to be the main job of the pressure sensor. Both NA's and Turbos will retard timing under load, just like the old vacuum advance/retard distributors do. Testing has shown it has little effect on fuelling, but the ECU may use it in an "accelerator pump" role, to boost fuelling when the throttle's opened suddenly. A lot of EFI systems that use an AFM as the main load sensor do that.

On S5's the pressure sensor does seem to have an effect of fuelling as well as ignition timing. A member here did some ECU datalogging on a S5 Turbo, and it showed the AFM reached max travel quite quickly and the pressure sensor then became the main load input sensor. That was a turbo, NA's may be different.

On turbos the pressure sensor also runs the boost gauge, and the ECU cuts fuel when the pressure sensor sees 8.6psi.

Don't ever unplug or disable the pressure sensor; you risk serious engine damage.