Stock FPR.. Couple of Questions..

[naughtika]

1. how does our stock FPR work? I know the vacuum retains it to 43.5psi

2. what will happen if the FPR solenoid is removed?

3. Can we run a vacuum hose straight into the stock FPR?

reason I ask the above questions.. I had a look at Teppei's car today and found that the FPR's vacuum hose is directed hooked up to the plenum.. stock FPR solenoid was taken out of the vacuum hose loop, but I saw that the electrical part of it is still intact and another vacuum hose is looped to it, so it doesn't get dirty inside..

any thoughts?

 

[TME_Steve]

You know what, it's something I actually don't know, i assume it's a cold start thing? Because if you measure the pressure going in to the FPR from the hose it just follows manifold pressure.... Maybe Jonson?

 

[VOLK]

I reckon you're spot on Shteeeeeeeben, reading various US DSM tuning forums I found out that during cold and warm starts the solenoid prevents vacuum getting to the regulator, increasing rail pressure.

 

[naughtika]

so does that mean, even if we take out the FPR solenoid in the vacuum hose loop, it should still work?

so would that mean, if one car has this setup, his cold start up and idle would have a hard time of maintaining 14.7 afr?

 

[VOLK]

I asked Teppei if he ever has issues with cold or warm starts and he said there was never any issue. Seemed to start fine at your place when cold too...I guess Mitsubishi were aiming for less injector duty for finer control of afrs with raised pressure rather than larger duty to achieve target ratio? That's my guess anyway, I'm no mechanic/engineer

Even without a FPR solenoid, feedback from O2 sensor to achieve stoichiometric combustion only occurs above a certain water temp and/or after a certain amount of time I think, so at the point where it's warm enough to aim for 14.7, the FPR solenoid probably won't be used.

 

[TME_Steve]

Assuming my assumption is correct, and it's only for cold start you live in QLD, the car came from/is designed for Japan, it's REALLY cold in a lot of places there!

Eg here

and here too

But it won't be maintaining 14.7 at that point, it would be richer anyway.... The ECU fires all injectors at once and stuff during cranking on cold starts too so it's after a super rich condition, I figured that's the only time it would do anything....