Aux air regulator on L-Jetronic

Sean

Sean

new to Fiat
Quick question-

With no power, is the aux air regulator normally open or closed?


I've removed mine and can blow air through it with no power applied. The manual implies it is normally closed but doesn't say it directly. Keep in mind I am not diagnosing a single symptom but bringing back a car that has sat for several years so I have everything apart anyways.

I've just about got the engine stripped down to a long block in the car so any encouragement is welcome too. :mallet:
 
Auxiliary Air Valve

The Aux Air Reg, off the car or cold, is open. Looking at the internal passage, it is actually about half open. It is controlled by a bi-metal coil spring, much like old-time chokes. As the coil spring heats, the valve gradually closes. The electric connector applies 12V to a small heater inside the assy, which speeds up the closing. With a hot engine, or after the voltage has been on for a while, the valve is closed.

Brian, "In da UP"
 
OK, so it's important that the valve is bolted to the engine block directly. That's good to know. I had thoughts of remote mounting it just because I didn't like the way it was covered up by the rad hose but now I will put it back in its place. It's interesting it was just hanging by the hoses and not fastened to the block when I got the car.
 
Aux Air Reg Location

That's an interesting thought....I think that the internal 12V heater actually does the shutting off, much faster than the head warming. When I tested mine, I put it in the freezer to see how much it opened. Then I took it out into room temp and applied 12 Volts, and the regulator slowly closes. (minute or so). I also put it in the oven with no voltage on, and it is closed by normal head temps (above 150 F).

The 12 Volts is alway on the regulator with the ignition on, so the internal heater is also on. It may well work away from the head. You can check to see that it closes all the way with 12 Volts on, if so, you're in business.

One drawback to this move would be that you'd lose the failsafe mode, if the internal heater or connecting wires malfunction. Bolted to the head, the valve closes with just the head heat. Also, if you turn a hot engine off, the engine mounted valve would open up only as fast as the head cools, but your remotely located unit will cool down fast and open quickly. This wouldn't be catastrophic. Upon hot re-start, the idle would be faster for a half minute or so.

Just for the failsafe mode, I think I'd leave it on the head.

Good luck with that engine!

Brian, "in da UP"
 
Interesting posts,,

as mine hasn't worked since I baught it in 1987 :eek:, Retired now, so hope to get to it this summer. Thanks for the info .
 
Sparks said:
One drawback to this move would be that you'd lose the failsafe mode, if the internal heater or connecting wires malfunction. Bolted to the head, the valve closes with just the head heat. Also, if you turn a hot engine off, the engine mounted valve would open up only as fast as the head cools, but your remotely located unit will cool down fast and open quickly. This wouldn't be catastrophic. Upon hot re-start, the idle would be faster for a half minute or so.


Brian, "in da UP"
Click to expand...

I will want to avoid a high idle after a hot start up.

This is why I'm borderline OCD about learning every detail. If I don't know how that valve works then I would have indefinatly wondered why the 'choke' function was working on a hot engine with the valve mounted to the firewall.
 
!

As a "quicky" diagnostic to see if the aux. valve is working, you can pinch the hose shut with a pair of needle nose pliers. If the idle drops, you know the valve is open. If it doesn't drop, you know the valve is closed (or clogged).
 
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