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Topic: Need info about WOT cutout relay (Read 5309 times) previous topic - next topic

Need info about WOT cutout relay

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?

Need info about WOT cutout relay

Reply #1
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.

Need info about WOT cutout relay

Reply #2
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.

Need info about WOT cutout relay

Reply #3
Quote from: TheFoeYouKnow;452229
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...


Need info about WOT cutout relay

Reply #5
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.

Need info about WOT cutout relay

Reply #6
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 flanges from and a high temp gasket material that can also act as an insulator between the steel flange 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.

Need info about WOT cutout relay

Reply #7
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.

Need info about WOT cutout relay

Reply #8
Going to try to get flanges 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.


Need info about WOT cutout relay

Reply #10
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?


Need info about WOT cutout relay

Reply #12
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?


Need info about WOT cutout relay

Reply #14
Quote from: jcassity;454106
,, oh and when you pick heat or AC, the wot is in play.

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.