IW STi Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
17 Posts
Discussion Starter #1
The top half of the 2006-2011 Cadillac DTS 91MM19M Right Secondary Air Injection Check Valve, AC Delco 47259JY, looks conspicuously like
the left side air injection valve for the "06-17 Subaru Impreza WRX STi Forester 14864AA020"

Since a lot of manufacturers, simply make slight tweaks and pull the same part off the shelf for manufacturer costs savings, does anyone know if that is trues in this case. Are the barometric pressure sensor readings the same? Has anyone noticed other cross listings?

For example:
 

·
Registered
Joined
·
17 Posts
Discussion Starter #2
Maybe no one cares, but if we really want to get to the bottom of this, we would need to start compiling a set of either voltage values (or resistances) as a function of altitude...has anyone done this?

Maybe in the manual...

Based on what I see from the diagnosis part of shop manual, the following pins
exist:
1 = should be 4.5 volts or more. The circuit is shared with the electronic
throttle.
2 = Connection to Engine Control Module, should be R >= 1 MOhms, relative to
ground
3 = ground for sensor, should be less than 5 ohms at the harness. This ground
is shared with the MAP, electronic throttle, and coolant temperature
4 = ground to valve solenoid
5 (missing, not used)
6 = power to valve solenoid from control relay

My interpretation is that the barometric pressure sensor is effectively a variable resistor between the ground (pin 3) and pin 1. The barometric pressure sensor (variable resistor) acts as a voltage divider. This is why the Pin 2 is the ECM, engine control module and is likely using pin 2 to measure the voltage...hence the comment that it should be 4.5 volts or higher (dependent on atmospheric pressure). Then pin 2 reports this value in some look up table to modify the engine parameters.

If we want to crowd source this information, we either want a table of
1. resistances between pin 2 and 3 (ground) for various altitude.
2. or turn the key on (engine off)
and measure the voltage at pin 2 with the key on (measured at A27, connector B134 of the ECM).

Any easy way to do this, would be:
A: If anyone who lives in the bay area and wants to go to Lake Tahoe for the weekend, could measure resistances at different altitudes....or
B: If someone has a spare that is good, but has a stuck valve that I can borrow, I could try simulating altitudes with a bicycle pump and convert psi to altitudes. My sensor is bad, so I wouldn't trust the data.
 

·
Registered
Joined
·
336 Posts
this would be great to find out...would be awesome if we could get a simulator to potentially eliminate the sensor all together too...
 

·
Registered
Joined
·
17 Posts
Discussion Starter #4
It would be really cool but that can't happen. Air Pressure will change with altitude. Even if we could deduce which altitude we are at by GPS, low barometric pressures (due to storms, for example), can change pressure that is not predicable by altitude. I would guess that Subaru probably sets the timing based on the barometric pressure.
 
1 - 4 of 4 Posts
Top