Thread: Dual Intake
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Old 04-17-2008, 03:17 AM   #18 (permalink)
trebuchet03
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The Miata - '01 Mazda MX-5 Miata
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Quote:
Originally Posted by tjts1 View Post
In extreme cold weather it helps warm up the engine faster. Most of these cars also use a hot wire air mass meter between the airbox and the throttle body. The sensor works by measuring the amount of electricity required to maintain a preset temperature on a heated wire in the air stream. It also uses a built in thermometer to reference the air temp. The air flap mechanism in the volvo airbox works to maintain a minimum 70f intake temp in order to make the AMM readings more accurate. The problem with the volvo device is that its controlled by a wax filled thermostat device that pushes against a spring. When the thermostat fails (usually after 5-10 years), the air flap goes into hot air only setting. In this situation the intake temp shoots up to 180-200f, slowly destroys the AMM and increases NOx emissions by a factor of 10 and drops fuel economy below 20mpg. Most volvo mechanics know to replace this $5 item but more often than not, these cars end up in the junkyard due to failed emissions test.
So it wasn't the hot air directly and instead the hot air destroyed the sensor? I mean, my car uses that same type of sensor - but there's nothing to keep the sensor at a certain temperature (and I haven't had any problems with adding heat etc.). Did volvo use a part spec'd for a small temperature range (thus resulting in bad readings when out of range)?


All that said - having a dual intake would be an awesome way to do some testing... you could do ABA on the fly if you're got it rigged for on the fly switching
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