Skip to main content
Topic: Boost PSI in reg vs prem on the fuel selection switch? (Read 1295 times) previous topic - next topic

Boost PSI in reg vs prem on the fuel selection switch?

I finally hooked the stock gauge up for the time being, and it is only hitting 8-10 psi, doesn't matter where the fuel selector switch is set. The light on the switch does not light up either. (this is an 88 5 speed also)

I believe it is something with the switch, but want to rule out other problems.

Boost PSI in reg vs prem on the fuel selection switch?

Reply #1
Did some googling, and did read that regular mode limits boost to 10 psi and retards timing, so i found the info!

Boost PSI in reg vs prem on the fuel selection switch?

Reply #2
Those rocker switches have a tendency to go out after 24 years of operation.  :P  They're expensive to replace too.  Also, the switch is just about useless without the factory boost control solenoid.  It's a little cylindrical black plastic piece with two vacuum nipples on it, one goes to the intake side of the turbo and one to the output side of the turbo under the intercooler, on the T fitting that goes down to the waste gate actuator.  It's a piece of .  It is the cause of a lot of boost leaks if it's still present.  Don't replace it with another factory solenoid, either get something like a Greddy electronic boost controller or a manual boost controller from NSX or boostvalve.com  Even if it still functions it needs to be replaced, for the safety of your vehicle.
1987 Thunderbird Turbo Coupe (daily driver) - T5, Short Throw, Ranger roller cam (soon to be Boport 1.5), stock turbo and TMIC (also soon to change.)

Boost PSI in reg vs prem on the fuel selection switch?

Reply #3
That "virtually worthless" switch also puts the computer into a different timing map when you switch it to premium.
88 TC 5speed, 168000+ miles, stock 2.3T long block, ported RFE6 exhaust, Evergreen T3 running 15#'s.
Up next: FMIC, fresh air intake, ported intakes, ported big valve head.

 

Boost PSI in reg vs prem on the fuel selection switch?

Reply #4
Crack the switch open and make sure it sticks in the prem setting.  Then put a MBC on it and call it a day.

Or, if you can, just take the leads off the back for prem and wire them togehter and THEN call it a day.
1987 Thunderbird Turbo Coupe (daily driver) - T5, Short Throw, Ranger roller cam (soon to be Boport 1.5), stock turbo and TMIC (also soon to change.)

Boost PSI in reg vs prem on the fuel selection switch?

Reply #5
I have an extra switch module i pulled at pic a part, I'm probably going to use it and replace the switches with good quality toggles. Then get the manual boost controller when funds permit.the pic a part piece has the antenna switch also, which I don't need, thought about using it as a kill switch :D