If the factory boost sensor on an '87 TII is not working, will the ECU still cause fuel cut? I know the fail-safe signal it sends to the ECU is 3.82 psi, so if the computer only sees 3.82 psi, then it will never see fuel cut and will blow my engine due to lack of fuel, right?! I just got my TII a few weeks ago, and have only driven it a few times. I am doing some body work and am fixing it up mechanically as well (general maintenance). It runs great, way faster than my last 3 N/A RX7s. I checked the compression and its good, around 90 psi on each housing. I havent checked the sensor with a vacuum guage and voltmeter yet, but I will the next time I go to my friends garage to work on it. Just wondering if my theory is correct. Later.

 

Fuel cut defencers are limiting devices - they do not replace the signal from the stock boost sensor, they just make sure that it does not go above 3.82 volts (about 7.5 psi boost). If the stock boost sensor is not working, you will not get correct fuel maps for any boost, even 1 psi! This would kill your engine quickly. By the way - if your stock boost guage shows boost, the factory sensor is OK, since the guage is wired directly off of it.

Irv, Keith's dad

 

This has been discussed on the TeamFC3S.ORG list recently...

The boost sensor/level does NOT affect fuel delivery.&nbsp This has been confirmed with an o-scope watching the fuel injector pulsewidth signals - what does affect the fuel delivery is the airflow meter signal.&nbsp This is specifically for the 1986-1988 FC's, but it probably applies to later 1989-1991 Kouki models also (even with the different airflow meter).

What the boost sensor probably does is retard timing versus boost pressure.




-Ted

 

yeah it doesn't effect the fuel map
i ran my car for about 3 or 4 months without the boost sensor, and still run fine..