Fox T-Bird/Cougar Forums

I'm starting a new project.  I'm building an active exhaust, and I'm using fast actuating electric exhaust cutouts (that I have to first build), but I want to be able to have them open based on percent load.  Since I've been tuning with a Moates Quarterhorse, I've found I have control over things I otherwise wouldn't and it occurred to me that I can adjust the load at which the EEC opens the WOT cutout relay for the AC compressor.  What I need to know is: Can anyone tell me if the EEC commands the relay open when the AC isn't actually on?  I don't know if the EEC has to first see signal on the ACCS (pin 10, pk/lb) circuit to enable WAC (wot cutout pin 54, o/lb), or if it will command the relay even when it doesn't see V on ACCS.  Anybody have any idea?

Put your meter on the pin 54 circuit. With the key on you will have 12v. When the EEC picks the WOT  AC cutout relay you will have ground.

I know that, but I'm a ways out from being to the point where it maters, and I was hoping someone could save me the trouble.  I'm not really positioned well for practical testing of the control circuit at the moment.

The PCM provides ground to energize the cut out relay and opens ground at around 75% throttle... AFAIK this function operates regardless of whether A/C is in use or not... There is a 12v feed to the ECM just after the low pressure switch and before relay that's used to determine idle speed when A/C is activated...

So you're saying wot cutout is a n.o. relay not a n.c. relay?

Is it n/o or n/c ? Good question, I assumed it was n/c.
Looking at the EVTMs, 83-no relay,  84-85 shown as n/o,  86-88 shown as n/c.

EVTM seems to suggest n/c.  I tested one of my cutouts last night and the results were encouraging, I need to figure out how to adjust the zero position of the valve now.  Then, I need to find a good material to make mounting s from and a high temp gasket material that can also act as an insulator between the steel  and the cast aluminum of the valve.  Verifying the WAC circuit is about 10 steps down the list.  If WAC isn't a viable control method, I'll use a WOT switch from a nitrous system.  Problem is, if I do that it's no longer EEC controlled, and I can't tell people I have an active exhaust.

I priced out commercially available electric exhaust cutouts at about $450 a pair, and my research says they take 2 to 3 seconds to fully open.  That's not fast enough.  By the time they get open, it's almost time to close them again.  what I'm working on should be able to fully open in 180ms to 220ms.

Going to try to get s made soon.  My T-Bird is still in storage for the winter, but once I pull it out, I'll get to testing the viability of WOT cutout for valve control.  I've got my valves zero'd out, and I have a sub-harness mocked up. Just thought I'd update.

I've heard of vacuum operated cut outs, but never WOT controlled by EEC. I'm taking notes.

I like some of the stuff Foe plays around with,, im not so embarrassed now to post up my latest idea.

something tells me you would be better off with a vac actuated check valve,,, it would be set to be open the amount you want for normal running but the door would pull open when there is no or little vac by a spring assisted lever.

im just makin this stuff up as I go.


so,, what the heck are you planning to achieve with this?

quiet "pass inspection car" but a loud hard core sound when you want to intimidate the other guy?

,, oh and when you pick heat or AC, the wot is in play.

We don't have inspections here.  I have a 2.5 inch non cat H-Pipe, but a 2 inch dynomax turbo cat-back. I like the cruise sound, but with my build, I start running out of flow around 4k.  At WOT, these will open to uncork the restriction and sound great, but ultimately let me keep my mellow, drone-free cruise sound. Active exhaust, for the win.  This is done on new Corvettes and the GT350s, and the Hellcats; why not me?

exactly!

I'm pretty sure WOT cutout is always active.  Once I pull her out for the spring, I'll verify.  Right now, it's stored 50 miles away.

NOW I'm excited.  I've discovered that the s I need to have made are dimensionally identical to 2.5" T3 turbo outlet s.  I CAN JUST BUY THEM!

Update.  WOT cutout, at the moment, is non-feasable.  The relay is grounded (on) the moment you turn on the ignition and stays on until AC is requested.  It function like a backwards AC clutch relay.  I could fake a constant AC request, and the valves would cycle open at startup a second or two then close, but that would effectively also either disable the AC clutch or force me to install some sort of manual interrupt in the circuit.  I'll still go forward using a 3 position switch for it (Off, Auto, Manual On), and I'll add the active control when I figure it out.  I considered a nitrous WOT switch, but that's my low-tech backup plan.

How about using the n/c contacts of a relay to activate the cutout?

So, I've been moving forward, here are some pics.  I may have a workaround solution for my issue with the way the WOT cutout works, I'll update on this later.  For now, pics.

A couple more.

Last one, almost ready to go on the car.

Ok, I think I've got a way to have everything I want.  Yes, that's a dp3t double pole triple throw switch (good for you for catching that).  Positions left to right are manual, off, auto.  The weirdly shrunken looking relay in the bottom right is for the cutouts.



Here's what that looks like

are those "commons" electrically isolated?

I'll have to go back to the datasheet to answer that.  I haven't wired it yet, too many irons in the fire.

Update. 
Today I blew the dust off this project and cut my H-Pipe, then welded in the d pipes it appears I fabbed 2 WHOLE YEARS AGO.  I mounted up the TB's and as expected, they leak just a tiny bit around the plates.  I don't care about that, but what I DO care about, is that if exhaust is flowing through them at all times in ANY measure, they're going to run hotter than I wanted.  This whole thing may just self destruct; but if it doesn't, I'll try to start wiring up simple controls I can operate while driving, before going on to build the integration I've planned on from the beginning.  At least I've managed to move my little experiment onto the vehicle.  Finally.

Update, it worked.  It was awesome, and about a week later, as predicted, self-annihilation. I installed block-off covers and cut out most of the wiring I added.
I suppose if Gumby wanted to, he could open them back up and use a vacuum actuated cutout or an electric cutout out actually made for the job.