987.2 PSE to stay closed when switched to OFF mode

[pcormier]

I am installing cat-less European Racing Headers headers on my 987.2 Cayman S when they arrive in June. I’d like to modify the car's electronics so the PSE valves stay closed, with the exhaust quiet, when the factory button is OFF and stay open, the exhaust loud, when it’s ON.

Years ago I had a pair of these cat-less headers installed and was frustrated that even when my factory PSE button was OFF the valves opened and the car was loud when I was aggressive with the throttle. This is problematic when I’m in neighborhoods and in other situations where I don’t want to call attention to the fact that I have the throttle open.

I’m not really interested in setting up geo fences for certain areas of town using a Track Nanny. I'd like to just press the PSE OFF button. I am open to dongle like the DYI 718 PSE Switch or other external controller, but I like the idea of a clean factory-like setup.

I’m mechanically skilled, and am OK with a soldering iron and related equipment.

Can someone help me get started with this project?

[blueline]

I am installing cat-less European Racing Headers headers on my 987.2 Cayman S when they arrive in June. I’d like to modify the car's electronics so the PSE valves stay closed, with the exhaust quiet, when the factory button is OFF and stay open, the exhaust loud, when it’s ON.

Years ago I had a pair of these cat-less headers installed and was frustrated that even when my factory PSE button was OFF the valves opened and the car was loud when I was aggressive with the throttle. This is problematic when I’m in neighborhoods and in other situations where I don’t want to call attention to the fact that I have the throttle open.

I’m not really interested in setting up geo fences for certain areas of town using a Track Nanny. I'd like to just press the PSE OFF button. I am open to dongle like the DYI 718 PSE Switch or other external controller, but I like the idea of a clean factory-like setup.

I’m mechanically skilled, and am OK with a soldering iron and related equipment.

Can someone help me get started with this project?

Tom has put together this for 718s. No idea if it can be adapted to your 987.2 but it might be a place to start.

viewtopic.php?t=2965


Also, Cargraphics (Germany) makes valve controller devices for Porsches.

https://www.cargraphic.de/index.php

https://www.cargraphic.de/en/your-vehic ... 872-s-34l/


And, if available for 987.2s, an aftermarket tune might do the trick by enabling strict "On or Off" functionality.


By the way, welcome to Carpokes.

[Tom]

I am installing cat-less European Racing Headers headers on my 987.2 Cayman S when they arrive in June. I’d like to modify the car's electronics so the PSE valves stay closed, with the exhaust quiet, when the factory button is OFF and stay open, the exhaust loud, when it’s ON.

Years ago I had a pair of these cat-less headers installed and was frustrated that even when my factory PSE button was OFF the valves opened and the car was loud when I was aggressive with the throttle. This is problematic when I’m in neighborhoods and in other situations where I don’t want to call attention to the fact that I have the throttle open.

I’m not really interested in setting up geo fences for certain areas of town using a Track Nanny. I'd like to just press the PSE OFF button. I am open to dongle like the DYI 718 PSE Switch or other external controller, but I like the idea of a clean factory-like setup.

I’m mechanically skilled, and am OK with a soldering iron and related equipment.

Can someone help me get started with this project?

Thank you for posting this here, and hopefully we can help you do this.

There is some urban folklore about causing damage to the catalytic converters and/or the motor itself if you drive the car hard with the PSE flaps shut. I don't know how true it is, but mention it in case you weren't aware.

To start, I assume you have seen the 718 PSE DIY Switch, here: viewtopic.php?t=2965

I've never worked on the PSE system on a 987.2, but would be willing to bet that it is very similar.

The basic system is very simple. The solenoid has 2 wires going to it. When 12 volts and ground are applied to the wires, respectively, the flaps close. Otherwise, the flaps open. That's it, super simple. Think of the solenoid as a light bulb. Turn the light on, the car is quiet; turn the light off, the car is loud. The factory computer decides on its own when to apply power, based on the switch, rpm, load, etc., etc., which is why the cabin button doesn't always follow orders.

To make an override switch on a 987.2, you need to know 4 things:

1. Where is the solenoid? You'll have to look for it -- if you find the vacuum hose going to the PSE diaphragm and trace it back to its source, that should take you to the solenoid.

2. What electrical connectors do you need? It's highly likely that the solenoid will use Junior Timer Connectors, an example of which is pictured below. (If so, the connectors listed for the 718 are different and won't work.) See the link below for a thread on Junior Timer connectors, which includes part numbers and sources.

Junior-Timer-2-pin.jpg (51.27 KiB) Viewed 1268 times

Link to info on these connectors: viewtopic.php?t=565

3. What is the polarity of the 2 wires going to the solenoid? To determine this, you need to back-probe the connector with a multimeter when the PSE flats are shut (i.e., when the solenoid has both ground and 12 volts on the wires). One wire will have ground, the other wire will have 12 volts. (Put the black probe on a good chassis ground point, and use the red probe to back probe the connector. One wire (the ground side) will have continuity to ground, and the other wire (the 12 volt wire) will have 12 volts to ground. Porsche is pretty consistent with wire color schemes too, so the ground side will probably have a brown wire with a colored stripe, and the 12 volt side will likely have a black (or red or yellow) wire with a colored stripe. No guarantees on that, but it's a good reality check. There is no 'normal' in terms of which side (Pin 1 or 2) is ground vs. power, at least that I can see. Some models have ground on pin 1 and power on 2, and on other models it's the opposite.

4. Which wire is the control wire? On all the cars I've tested (981, 991, 718, 997), the solenoid is turned on an off by ONE of the two wires. On the newer cars, the computer cuts the 12 volt side to turn off the solenoid and make the car loud, but IIRC the ground is the control wire on the 997. You'll need to back-probe the connector. One of the wires will never change -- it will have ground (or 12 volts) regardless of whether the PSE solenoid is powered up or not. The other wire either completes the power circuit (to quiet the car) or cuts the power circuit (to make the car loud).

Armed with that info, it's just a matter of building the harness/switch in a manner similar to the 718 DIY version. The 3-way switch hijacks the control wire going to the solenoid and routes it to the switch. You then use the switch to either 1) cut power to the solenoid to open the PSE flaps; 2) send power to the solenoid (be it ground or 12v) to close the flaps; or 3) send the original factory control signal back to the solenoid to let the factory control system work as design.

Hope that makes sense, and sorry for such a long answer, but wanted to put it all out there. Happy to walk you through any/all of it as you work through the project. And, of course, when you get it working, we need to hear all about it.

[Tom]

By the way, I'm with you on trying to make the override switch look factory. I included the free-hanging switch in the 718 guide for the easiest install, but I've had good luck re-purposing factory switches for things like this. And, I'm not sure I've ever seen a Porsche without a few blank switch locations In my 944, I wired my garage door opener to an old central locking switch, and put it in one of the console blanks. Looks like it came from the factory that way...

[pcormier]

Thanks Tom and blueline. I have time today to investigate. To address Tom’s numbered comments:

1. Where is the solenoid?
Here:

IMG_0557.jpeg (1.02 MiB) Viewed 1168 times

2. What electrical connectors do you need?
It doesn’t look like that one exactly, but close. Here are some photos.

IMG_0562.jpeg (41.22 KiB) Viewed 1168 times

IMG_0561.jpeg (33.5 KiB) Viewed 1168 times

IMG_0560.jpeg (38.02 KiB) Viewed 1168 times

IMG_0563.jpeg (33.63 KiB) Viewed 1168 times

3. What is the polarity of the 2 wires going to the solenoid?
Shall i carefully push the red thin pointy multimeter probe next to one of these wires to get to the metal connector inside?

IMG_0564.jpeg (36.63 KiB) Viewed 1168 times

And the black one to ground. Using the continuity setting for each wire?

IMG_0485.jpeg (32.45 KiB) Viewed 1168 times

4. Which wire is the control wire?
Should i still use continuity setting here, while switching the factory PSE switch on and off, and report results? Or DC Volts? Pardon my ignorance, but want to make sure i get this right and document it well for others.

IMG_0486.jpeg (29.01 KiB) Viewed 1168 times

I can continue when i hear back. Thanks again!

[Tom]

Responding the 4 points....

1. Mission accomplished -- nice easy access too!

2. Yes, that's a Junior Power Timer connector. They have many variations of that connector, mostly changes to the spring clip, but they are all compatible with each other. Any/all of the 2-pin connectors listed our Junior Timer Connector thread will work fine.

3. Hard to say for sure, but it looks like that connector is sealed on the back side. Either way, I doubt you'll be able to make a connection with the probe from that side. What I do is create a patch cable that plugs into that connector, and then onto the solenoid -- basically an extension cord for the connector. You can then bare the wires in your extension cord to probe them. If you don't have the connectors yet to make a patch like that, and don't want to wait, you can just pull the connector off the solenoid and put the probe into the electrical terminals inside. You won't be able to hear the exhaust to confirm what mode it's in, but you can still test it. By pure happenstance, the tip of standard probes will usually click into the pins for hands-free testing. (Although don't know if that's true with vintage Radio Shack Multimeters....).

With the car running and the PSE on (factory quiet mode), set the multimeter to continuity (straight up on your meter) and touch the two probes together to confirm the meter beeps or shows ~0 ohms resistance. Then put the one probe into one of the two connector pins (being careful not to short them) and the other probe to a good chassis ground. One of the two sides should beep, indicating that is the ground side. If neither beep, or if both do, report back and we can sort that out.

4. You'll have to experiment. We don't know if the control wire is positive or negative, nor which pin in constant and which one changes to control the solenoid. If you found that (only) one wire was always grounded in step 3, then there's a good chance the other wire switches from 12 volts (when PSE is on/quiet) and ground or open (when the PSE is open/load). To check for 12v, put the red probe in the terminal pin, and the black wire on a chassis ground, while the multimeter is set to DC volts. You can practice on the battery first, one probe on a post and the other on a chassis ground -- with due re for battery safety of course.

[pcormier]

Thanks Tom… more:

Pin 1 seems to be green/yellow wire
Pin 2 seems to be red/blue wire

3. What is the polarity of the 2 wires going to the solenoid?

With PSE switch OFF, continuity…

Pin 1 to ground didn’t beep, but read

IMG_0488.jpeg (31.31 KiB) Viewed 1141 times

I am using the threads on the unibody that the aluminum engine cover bolts to. Not the best but convienient. There is a engine lift hook nearby, I tried that it seems a little better, but similar readings.

Pin 2 to ground, .0L, no continuity.

IMG_0489.png (407.58 KiB) Viewed 1141 times

With PSE switch ON...

Pin 1 and 2, .0L no continuity to ground

4. Which wire is the control wire?

With PSE OFF DC Volts

Pin 1, .066 V
Pin 2, .0L

With PSE ON…

Pin 1, 4.53 V
Pin 2, 14.8 V

I’m probably screwing something up.

[Tom]

Do this, set the MM to dc volts and check the battery voltage. Just to confirm you are using it right.

Then with the mm in dv volt mode, put one probe on each pin in the connector, being careful not to short anything. Turn the PSE on and off. With the PSE in quiet mode (not sure if you call that on or off?), you should see 12 volts (i.e., battery voltage) across the leads in that connector. Do you? Then when you set the PSE switch to loud mode, you should see little to no voltage across the leads. If you see something different, then either you are doing something wrong while testing or that car works differently from all the other models (which I have to doubt...).

By Porsche convention, it's very likely the red/blue wire is the positive side and the green/yellow is ground. So I'd put the red probe on the red/blue side of the connector. If that's backwards, the test will still work, but the mm will show -12 volts....

[pcormier]

Tom,

Doh, I was confused, I was checking DC volts between the pins and ground. Hope I didn't screw anything up. And, by 'PSE OFF' I mean the switch on the dash un-pressed, its associated LED not lit, valves closed, quiet. The opposite for ON.

I just measured DC voltage across the pins of the connector that is normally attached to the solenoid. Car was running and the connector, as shown, obviously isn't plugged in so in this case the mechanical PSE valve was unaffected and open/loud.

IMG_0604.jpeg (2.66 MiB) Viewed 1120 times

with...

PSE OFF:
14.67 V

PSE ON:
0.01-something volts, essentially no voltage.

I think that is what you expected.

[Tom]

Great, now we're getting somewhere!

So, as I understand your tests, that would mean PIN 1 supplies ground, and PIN 2 supplies battery voltage, when the PSE system is trying to close the flaps and quiet the car.

Now do this, with everything the same as you have it, keep the red probe on pin 2, and ground the black probe to the chassis. You should still see battery voltage (e.g. 14.67) when the PSE switch is set to quiet the car. Assuming that checks out, then change the button in the car to see if the battery voltage disappears when the PSE is trying to open the flaps and make the car loud. If you are able to toggle the battery voltage on and off with the PSE switch in the cab, then you know everything you need: Pin 1 is always ground, Pin 2 switches 12/battery volts on/off to control the PSE valves.

If you continue to see 14.67 v regardless of PSE switch location, then most likely the ground side is switched on/off to control the PSE. To confirm that, set the mm to ohms (or diode test with beep); then put the black probe to Pin 1 of the connector and see if you have continuity when the PSE flaps should be closed and no continuity when the flaps should be open. If that's the case, the the battery voltage on Pin 2 should be constant (and the pass-thru wire in the new harness) and the ground on Pin 1 is the switching signal.

Let me know what you find and I can help lay out the manual switch harness if helpful...