Lone Ranger

Those things usually just change the resistance values from the Mass Air Flow sensor to fool the computer into thinking there is more intake air being sucked in than there is. Very bad way to get the computer to inject more fuel. Some well balanced ECM tuning would be a better approach, but on an ecotec still isn't going to yield much power gain in and of itself.

Lynx

dont bother

en0oNmAI

These resistor boxes hook up to the air intake temp sensor. It fools the computer into thinking its taking in COLDER air and not more of it. Throws the computer into its warm up mode (either open or closed loop) and sends a pre-determined amount of fuel to the engine instead of a monitored amount. This makes the car run over rich and gives the feeling of more horsepower. I had this setup on a ZX2 Escort with the ford Zetec engine in it as was recommended by the zx2 forums. Their setup was different in the fact that it was "tuneable" and several found 2-5 horse gains. Not worth the money and with something like this the computer actually "tunes" the resistor out and goes back to normal after a while. The setup they had for the Zetec was supposed to be turned on during racing ONLY to give that little extra. Never seemed very good to me. But things like this DO offer a VERY minimal gain. However NOT "feel-able" on a butt dyno which typically needs a 10+ change to be felt.

Lone Ranger

I thought the computer used a coolant temp threshold value as trigger for closed loop.

en0oNmAI

it might. i was just using the Zetec as a comparison. The fords use the IAT for some reason on the older Zetec engines. Not sure with ECOtecs or the new ford Duratecs.