Charge releive valve??
 

Hey guys, me and puma are doing the sillicone hose job on a 93 FD.. But, My question is, do the charge releive valve opens on the vaccum or on the boost ?

Thanks for a fast answer guys


Max

CLosed on boost, open on vacuum... just like your ABV

Nope! Open on BOOST from the secondary turbine. Closed under WOT. Basically, it vents charged air from the second turbine under light throttle allowing only the primary turbine to spool and keep air from the secondary turbine out...hence charge (air) relief valve.

If you vent it to the atmostphere, you can hear it let air out like a big boost leak, then when you got WOT, it will close and you won't hear the CRV anymore!

errr not quite.

Open at idle. Shuts closed above 4500rpm and then re-opens below 3250. It's that simple. If you pull it off the airbox and go for a blast you'll hear it rushing madly from 3500 to 4500 (pre-spool) and then promptly shut the hell up. It is just a BOV that has vacuum/pressure switched onto it by a 3-port solenoid. It is phsycally and functionally interchangeable with the ubiquitous Bosch BOV.
(Avoid the metal/metal Nippon Denso's (late 80's supras) as they sieze regularly. The plastic/plastic ND's leak under boost (eg Celica GT4)

-pete

Thanks for the correction Pete!....It's been about 6 months since I've had a "working" sequential system;)