Stay tuned - Toyota Yaris Forums

Bluevitz-rs · 02-15-2010, 08:50 PM

You have to think of it this way...

... with less back-pressure you get more exhaust out of the cylinder on the exhaust stroke, but the intake charge is still the same on a N/A motor. (ok, not EXACTLY the same due to valve overlap and the effect that has on pulling in air, but basically the same.) The intake charge will be "cleaner" than what a stock ECU is programmed for. The stock A/F ratio is based on the back-pressure being there and the amount of residual exhaust gasses still left inside the cylinder on the intake stroke.

A very simple cheat to make the ECU run richer is to trick it into thinking the engine is colder that it really is. If you add a resistor to the Water Temp Sensor and make the ECU think the engine is only running at 110°F or so it'll think it needs more fuel for running in the cold weather. (this might also set a code for the thermostat, but it's nothing major.)

Another method is to add a resistor to the intake temp sensor in the MAF meter. You can trick it into thinking it's sucking in air at -40°. This should have the same effect, but with less chance of setting a code.

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02-15-2010, 08:50 PM	#11
Bluevitz-rs 1NZ-6spd View User's Garage Drives: '05 6-Spd Vitz RS Join Date: Oct 2008 Location: Oshawa, Ontario, Canada Posts: 2,967	You have to think of it this way... ... with less back-pressure you get more exhaust out of the cylinder on the exhaust stroke, but the intake charge is still the same on a N/A motor. (ok, not EXACTLY the same due to valve overlap and the effect that has on pulling in air, but basically the same.) The intake charge will be "cleaner" than what a stock ECU is programmed for. The stock A/F ratio is based on the back-pressure being there and the amount of residual exhaust gasses still left inside the cylinder on the intake stroke. A very simple cheat to make the ECU run richer is to trick it into thinking the engine is colder that it really is. If you add a resistor to the Water Temp Sensor and make the ECU think the engine is only running at 110°F or so it'll think it needs more fuel for running in the cold weather. (this might also set a code for the thermostat, but it's nothing major.) Another method is to add a resistor to the intake temp sensor in the MAF meter. You can trick it into thinking it's sucking in air at -40°. This should have the same effect, but with less chance of setting a code.