Ok, maybe someone can let me know if this is even possible.

I've been having trouble with my check engine light coming on because of my pressure sensor. I took a look at the wiring coming out of the pressure sensor and it looks kind of rigged, there are two wires going into each of the terminals on the plug. Now when I turn the ignition on and jiggle the cables I can hear a click every now and then around the intake manifold. I looked under the car and saw that there's a replacement pipe between the Y pipe and the exhaust manifold.

So, has anyone heard of someone rigging up the aux ports this way?

 

Track down where the "extra" wires go to and you'll find whatever aftermarket part is tapping into the pressure sensor.

I seriously doubt this is at all related to activating the aux ports of the VDI, since a S5 already has that controlled by the ECU/2 solenoids/air pump. Adding some extra system would only be necessary if someone removed the air pump.

As for exhaust...it's not related to the aux ports on a S5.

 

It would help if we knew what year car you have.

IF it's a series four car, then the pressure sensor might very well have two wires coming out of the sensors elect plug where there is a brown/black wire. This additional ground wire was added by Mazda to correct a *problem* with the Afm (really and truly).

The other wires in that sensor should have but one wire. Like one black/white, one brown/white, one brown/red.

It has zip to do with the fifth and sixth port operation on a series four car, for sure.

This post only addresses the pressure/boost sensor wires, not the operation of the aux ports.

 

He said he was getting a check engine light, so that can only be a S5. But still, more info would be great. Or better yet, pictures...

 

Two wires out of each terminal of the boost/pressure sensor means.........it's screwed up totally.

Aux ports on a series five are driven by the Air Pump when their solenoid opens at? what? 3800rpm? It's written in the Fuel and Emissions Section of the series five FSM. They're not driven by the exhaust backpressure on a series five.

 

Ok, more info. It's a S5, 91, out of each terminal there are the following wires.



Going into B There's one G/Y and a white wire, the g/y goes into the harness and the white wire actually runs back to the ECU where the FSM says the g/y should connect. I suspect this is my problem.

Going into C There's the two Brown/Black wires that are attached to ground wires that attach to the back of the bracket that holds the pressure sensor. Should these be grounded?

Then into Terminal D there's two brown/white wires.

 

The jpg attached shows the plug.

It shows the plug from the WIRE side. Your plug once looked like this.

The Brown/Black is the ground wire. IF he/they added another wire to this, it should not hurt anything. But I see TWO wires going to the bolt that holds the sensor on the chassis. That's puzzling...a bit.

Brown/White is what is called the ref voltage. Why two wires is beyond me. I'm clueless about that. If you put a meter on it with key ON, it should show approx 4.5-5 vdc.

Green/Yellow is the output to the ECU. Why two wires is beyond me. It should have been a direct run of wire from the sensor to the ECU plug on the original installation.

At the ECU, how does that green/yellow look? He has two wires going into the socket on the ECU plug? Or one wire?

Key ON and all plugs connected, does the voltage at the ECU green/yellow wire read what the manual/FSM says?

I suppose the guy was trying to piggyback new wires to the sensor because he lost faith the original wires were any good.

OR just disconnect the sensor. Flip it over and attach the elect plug. Key to ON. The brown/white should read 5vdc and the green/yellow should read 3.4 to 3.6 vdc. Engine OFF, key ON.

EDIT: I see the Brown/White in the plug look like factory wires. I've never seen a series five, and maybe, maybe they use two ref voltage wires, quite unlike a series four. I've no idea what's up there. If it reads approx 5vdc, then it's ok imho.

 

I don't know why there's two wires to everything, it's weird, but they all connect to the correct places.

So the br/w put out 5v like it should with the key on and the grounds with the br/b looked good as well.

The gr/y seems a little off. I don't have a vacuum gauge but when the engine is idling it reads about 2.2v and when I rev it up it'll go up to 2.4v but it never hits the 2.8-3.2 that the manual says. It also seems to spiratically jump around going down to .06V even. I don't know if that's normal. I have a new pressure sensor in the mail And that's looking like what i'll need. Thanks for the help HAILERS

Also on a side note, who knows where this tube is supposed to go? It comes out from under the intake manifold and then just goes out to nowhere. This car needs a lot of work! When the engine runs I can feel hot air coming out of it and the car seems to kind of bog down when I can hear it putting out more air.

 

I can't tell what that hose connects to in the second pic, but it's either the air pump intake hose, which would connect to the air box or the bypass hose that goes from the ACV to the silencer muffler behind the bumper.

 

This hose?

 

Yes, that hose.

 

It's the same hose from the first pic. It doesn't connect to anything, which is my problem. When my car sits for a while it smokes like a banshee, and I'm trying to figure out if this is why.

 

It's supposed to plug into a plastic muffler that keeps you from hearing air pump noise above 3,500 rpm. Above this rpm, the air from the pump is bypassed to atmosphere. It has no effect on engine performance.

 

At first I thought *this is bullshit*, what with the smoke etc. Then I thought of a way it could make smoke. If someone put the ACV on, and left the round spoked checkvalve out, then that would be exhaust smoke coming out.

That''s the only answer I have for that. I'd remove the ACV and see if there is a round/spoked checkvalve in the silver dollar sized hole in the manifold.

If it's there, then I've not a clue. The airpump pumps fresh air to the ACV and then sends it to the exhaust PORTS via the checkvalve mentioned above. The checkvalve keeps exhaust gases from coming back into the ACV. No smoke or exhaust fumes allowed.

 

I've pretty much come to the conclusion that the smoking is it getting flooded out for some reason. Perhaps this pressure sensor is part of it. But I get horrible gas mileage and the car smokes really hardcore if I start it after not starting it for a while. It seems to happen more when I drive the car on the freeway for a long time and then park it overnight.

I did a champagne check and there's no bubbles coming from the radiator. I'm not losing coolant, or oil. The smoke is white and just smells like burnt.

Oh and just to be clear it smokes from the exhaust not from that tube that comes out of the ACV

 

Ok. I thought it was smoke from the ACV hose. Ignore the answer.

If the car gets severly flooded, once it does start they smoke a lot. Normal smoke for a severe flood. Also if it floods a lot, the fuel will get in the pan and thin the oil out. You need to make a fuel cut switch to prevent severe flooding.

 

So a good indication to see if this is the problem would be to see if the oil smells like gas? As far as the fuel cut off switch goes, isn't running lean a big concern? So I should start the car and leave the switch off then after a second or two turn it on?

I see that you're in forth worth, do you ever head out to the DFW meets?

 

disregard my statement about startup. I get how it's supposed to work now.

 

If your experiencing a lot of flooding problems, then make a fuel cutoff switch. It'll save you a lot of time/trouble and help the engine. Being flooded a lot does not help the internals of the engine like apex seals, oil control rings etc.

Yeah. If flooded, you turn the switch to off and then crank the engine over. The engine will still have Spark this way, and when it lights the residual fuel off, you flip the fuel switch to On and hoepfully it'll now keep running.

The deflood method of pulling the EGI fuses sort of sucks in that it also kills Spark when the fuses are out. That method works, but sucks.

 

Cool, well hopefully this will stop my smoking problem because yesterday it smoked, a lot. It's worrying the crap out of me.

 

So I got a new pressure switch today and there is no check engine light and it seems to be running a lot more smoothly. Let's see if it stops smoking now