So I’m currently wiring up my supp air valve with an aftermarket timer relay (for 45 second timer). I’ve read the wiring diagram and tested it all out with my voltmeter.
It appears that the supp air valve always gets a constant 12V while engine is running, and that the idle relay supplies a ground for it which turns it on. But my timer relay puts out a 12V + signal, which does nothing. I verified if I feed a ground to the relay output wire, the supp air valve trips.
Is there a different way to wire this up? Or do I need a timer relay that supplies - instead of + ?
Wow, it worked! I ran my 12V timer relay + output to standard relay wired as shown. It converted to - and my supp air valve now works for 55 seconds!!! (What I set it for)
O…K., Gregmatic … dumb question (well, two) time … (1) Why do you feel a need to have a delay timer on the A.A.V.? Isn’t the “piston” supposed to move on its own when the coolant is up to temp, to decrease the idle to “hot” speed? (2) there’s current going to the A.A.V.? What is that for? I thought it was purely a mechanical device in operation?
Oops - sorry, I got them mixed up. That did have me puzzled! btw, don’t forget there is apparently yet a THIRD “air valve” also on the XJS, the “extra air valve” (unless that is another Jag name for the S.A.V.?)
My understanding Paul is that the Extra Air Valve and Auxiliary Air Valve are two names for the same thing. Adjusts your idle speed downward as the engine warms up. Sits at rear of B Bank throttle area and piston moves as coolant warms up.
Secondary air is to help the catalytic converters and the Valve is on the a bank side. Essentially a vacuum timer valve.
is to provide a little bit more air when the AC compressor engages.
It has nothing to do with emissions or cat converters.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
12
Remember that the valve Jaguar used was actually a heater valve. Heater valves are normally open, so presumably power to it closes it. And you want the SAV closed after the 45 seconds.
Sure. Disconnect the existing power source to the SAV. Connect the 12V from your timer relay instead. Connect the other lead from the SAV directly to ground.
The Supplementary Air Valve on the A bank is for : (this applies to the US Market with Catalytic Converters)
Provides higher RPM when A/C is switched on
Provides higher RPM at start when 45 second timer is turned on, because the timer also disables vacuum to distributor so timing is slightly retarded (which would bring down idle) which runs engine a bit hotter so it warms up faster. This is purely to help fuel consumption when cold. It may or may not also help heat up cats faster, I’m not sure. Years before my 1988, the O2 sensors didn’t have the third wire to heat them up. But mine does, yet Jaguar still kept this feature? So no, the SAV is not directly for emissions, but it indirectly plays a part in the emissions part of the 45 second timer.
I’ve removed my A/C (for now), and have also disconnected the vacuum retard system to distributor. Also, my 45 second timer was kaput, as was the actual SAV. Only reasons I decided to get it all working again - One day I will put back my A/C. And even though my AAV works fine, I wanted a slightly higher idle when starting up, especially when cold. Now I got it! I can even hear the click from the timer relay now at exactly 58 seconds
And I’ve measured, it’s roughly 200 rpm higher with SAV open.
FYI, when engine is cold (65F ambient), instead of 900RPM idle, i get 1100RPM.
When warm, instead of 800RPM, I get 1000RPM.
Will have to wait until winter for final test, but I think it used to idle at 1000-1100RPM at 40F ambient.
Uh, no. The a/c use of the SAV came later as an additional use. There was a kit that was installed on early cars that added that functionality, and was made standard later. The original purpose was warm up and brought the idle speed up when emission controls shut off vacuum advance at startup. See page 304-305 of The Book.
Yep, so you can see my confusion … btw, regarding the valve that goes on the backside of the air cleaner housing (whatever it may be called), the rubber mounting grommet on mine is toast. Anyone know where to get a new one?
btw, regarding the valve that goes on the backside of the air cleaner housing (whatever it may be called), the rubber mounting grommet on mine is toast. Anyone know where to get a new one? 