Something everyone doing N/A turbo's needs to know about tuning

[Toysrme]

(for OBD-I cars)
What is one of the biggest pains in the ass for tuning the turbos? Tuning closed loop mode on the stock ECT. You can't modify the signal with any piggyback to do it by itself, otherwise the ECU will simply trim all the changes out in roughly 0.25 seconds from reading the o2 sensor<s>. How can you get around this??? Simple! Run open-loop more.

The OBD-I ecu's use the TPS signal for one thing, and one thing only... It triggers the ECU into open loop mode (around 75-80% throttle). Guess what happens when you're cruising around 40% throttle and the ECU see's the TPS signal going from around a 2v signal, to say a 4.5-5v signal. Instant open loop mode. Fuel wise in open loop mode you are disregarding all sensors except for AFM, IAT, and ECT. It simply looks the AFM signal on an RPM table, and adds in the IAT and ECT table modifiers. O2 sensor input can go rot in economy lean-hell.

This can be accomplished simply by installing a 5v relay in the fuse box, and wiring it to a switch mounted securly under the gas pedal that will close the relay (whenever you want open loop), sending the 5v to the TPS wire.

Not only that, but for anyone with a more advanced piggyback tuner, you can do powerful fuel tuning without swapping to stand-alone managements.

An Example:
3vz-fe owners, want to trow out those shitty 200cc injectors and be able to tune monstor 450cc+ injectors without a CEL, or worrying about the ECU fuel trims??? Simply trigger open loop mode at a ludicristly low setting, say 40% throttle. That way you can use a FPR to ACCURATELY tune the injectors at ONE SMALLER RANGE, instead of have one half-ass tune the entire closed-loop rpm range.

[Toysrme]

You could also easily set the relay up for something else. Say a boost switch that will close the relay at say 1.5-2psi.