boost

[NorwayGT]

what is the stock boost psi on a 93-95 mr2 (is 91, and 92 the same?), and how high can you safely go without doing any internal work?

[Piddy]

Stock boost is between 7-9psi... mine generally runs at about 8psi. If you search around you will come up with something like:

You can run 16psi w/ supporting mods.
Must get a boost controler and fuel cut defencer.

[JekylandHyde]

The OEM level of boost is 7 - 11.9 psi
If you are stuck at 7-9 psi, your ECU is keeping you in low boost mode for some reason.

[Piddy]

^Interesting... any ideas? I notice one thing that doesn't seem right. If my car gets warm.... and then I go down the freeway for like 5+ miles at like 70mph... my temp drops to about 1/4 way up the gauge. But then when I pull off the freeway it goes back up to 1/2. Is this a thermostat issue? I was thinking this cause my car will not boost at all unless the engine temp is at 1/2.... so most of the time going down the freeway... my boost cuts out.

[JekylandHyde]

The ECU goes into "limp mode" whenever it reads cold temps (out side air OR your coolant). When in limp mode, you will have limited boost )7-9 psi and your timing will be retarded.

You should not be boosting until your car is up to temperature regardless.

If your temps seriously come down while highway driving, it sounds to me like your thermostat is opening prematurely.
That would be my guess.

**side note, the ECU will also retard timing&boost when it sense knock/detonation:
http://www.jekylhyderacing.com/knock.htm

[Piddy]

^ Ya... that's why I dont boost generally when I'm going down the freeway.... which actually turns out pretty nice because then I use less gas. So is this a simple fix? Just replacing the thermostat?

EDIT: After reading that on your site... I could possibly need a knock sensor? Next time I take it in for service I will have my mechanic take a look see at it.

[JekylandHyde]

If your knock sensor is bad, you would have the check engine light on.

The thermostat is not a big deal to swap out.

[Piddy]

No check engine light... excellent... wasn't looking forward to that. Should I go OEM on that themostat? Or is there something specific I should look into buying?

[JekylandHyde]

TRD makes a lower temp thermostat.
That is what I use.

I think it is 160 degress ... oem is 180 degrees.