It doesn't have a traditional IAC. It has electronic pedals so the throttle plate (single butterfly in my case) is controlled by an electric motor/IAC unit. It mimics an IAC by openening the throttle plate at idle. I checked all hoses for the evap but didn't see the need for any component tests because of numerous system check sensors for the evap system. Some self check sensors are: evap valve flow monitoring (think MAF), leakdown detection (think map to check for bad vac. Hoses). Evap valve position monitoring (comparison between evap valve return voltage and engine map, temp, TPS, and previous two check sensors) so seemed to be capable of detecting any problems and displays a MIL. I do have access to refernce volts for set conditions (alldata pinpoint testing). But no MIL on the dash so didn't bother.
FYI the pvc valve is "hi-tech" also. Rh valve cover has a spring loaded screen/reed type valve that's made into the valve cover. Spring loaded to offer resistance to raise crank case pressure slightly to prevent natural blowby from healthy engines (from what I understand). It connects with a hose to a heated tube in the intake manifold (Ford calls heated pvc valve). Its shaped to control amount of flow from the engine and only heats when below 30 degrees. (Says alldata). Other valve cover is open to intake after MAF but before the tb to allow open flow into crank case.
At idle When I press the brake in the vac. Drops <1 in. Hg but when releasing the pedal it drops 7 in. Hg. I've never paid attention in past but seems a bit much.
The 5in. Hg is at any speed. 30mph is same in. Hg as 75 mph
Saturday, September 17th, 2011 AT 5:34 AM