3S-GTE Boost Control Modification

Subject: 3S-GTE boost control modification per Team Toyota Europe



 Toyota Team Europe came up with a very simple boost modification 
for the cars to go to something like 12.5 psi. As you know many kids try 
to go to 16psi and beyond, but this article is a practicular route to 
240-250 bhp on pump gas. The modification was used on the limited series 
Carlos Sainz GT-FOUR (ST185) sold in Europe.

 It is good for any 3S-GTE series 
motor, even though the late cars had air/air intercoolers, higher 
compression and a a revised ECU box.

1. Remove the turbo VSV (vacume control valve) and bore it out to 4.5mm. 
This will increase the boost to 12.5~13 psi.( Remember! The area goes up 
with the square of the radius - do not get lazy and use a 5mm drill bit, 
you will be way off the mark.) Re-install. It is located under the 
intake manifold.

2. Open up the CPU and solder a 4.3v ziener diode to the PIM sensor pin 
on the bottom side of the system board to the ground screw. This is the 
fourth pin on the bottom row with the AMP wiring loom connectors facing 
your belly and the ground is the phillips screw below and to the right 
of the long dual row of data input pins. The band of the diode goes 
toward the PIM pin (Important). This will bleed voltage to ground and 
raise the fuel delivery cutoff pressure to 14 psi.

So for seventy-five cents you get about 230 bhp from 190. With a big 
exhaust the TTE cars were seeing about 245bhp, with a big boost in 
overall torque as well. 

The Toyota ECU will retard the timing if the motor starts to ping. You 
will see a rapid rise in coolant temp if running hard under this 
condition. Either get better gas or turn down the boost a bit. Older 
motors with any carbon buildup will be touchy in this regard.  Also, the 
stock ECU runs fat up top, so this is not a true high performance 
solution, rather it is a solid midrage improvement.

So, for those who do not want to buy trick gas all the time, it is a 
very effective solution. Also, an installed adjustable control valve 
on the VSV solinoid with capped return nipple on the intake manifold, 
could turn the boost up by bleeding VSV air to atmosphere and the 
waste gate would not open so far.

Contributed by
Mike Shields

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