Help me understand the AAR please.

[Captain Obvious]

It's operated by a manual cable, pull it out for starting and push it in after a few minutes of running. The manual AAVs are for sale at the bottom of this page.

Thanks for that link. I remember breezing through that page a while ago, but I didn't read it closely enough to catch that line about a manual valve. I wouldn't be surprised of one of the older fuel injected Alfas used something like that.

My old Alfa had a twist knob on the dash that would actually hold the throttle linkage down. It was a fine thread and you could turn it to raise the idle. Heck you could even turn it fifty times and use it as "cruise control" on the highway. :stupid: It was all mechanical and acted on the original carb linkage. In other words, the end result was the same, but they didn't put in a separate valve for the task. Instead of including a path around the throttle plate, they simply opened the throttle plate a little.

Hmmm... All you need is a cable controlled valve that bypasses the throttle plate. I've got a couple leftover water control valves after my heater valve relocation project... :bulb: :laugh:

[TomoHawk]

You'll still need to run wires inside to a switch, unless you can devise some kind of timer or temperature-controlled switch.

[Captain Obvious]

You'll still need to run wires inside to a switch, unless you can devise some kind of timer or temperature-controlled switch.

Sorry TomoHawk, forgot to get back to you about how to control such devices. If I were to go to a solenoid valve, I would try to install a temperature switch into the thermostat housing.

So I was thinking about it a little more, and what would be the real ticket would be to use an analog temp sensor (like the one that's already there), and use that analog sensor signal to control an air valve that is more complex than a simple ON-OFF solenoid valve. The air valve should be open when the sensor indicates cold, and closed when the sensor indicates warm, and partway when in-between.

Kinda sounds like an idle air control valve, doesn't it? :bulb: Haha! Now vehicles have such devices incorporated directly into the throttle bodies!

[TomoHawk]

You could just get one of those electric fan thermostat switches? It would provide instant on-off functionality, which would probably drive you nuts, huh? If you want real "analog" idle control, then you'd want to add in a transistor to control your air valve. That assumes you've got an air valve that you can open partially. IMO, a stepped opening (full-open, half, closed) would be better than just open-closed.

After quick search I found that the Fords have something similar, but I couldn't tell if it was a proportional thing or on-off, and you'd need to modify the intake, but it was dirt cheap ($30 new,) so you could get one at the JY easily (probably.) It's just not the flow-through design that thew L28 engines use (so we keep looking.)

Edited October 4, 2012 by TomoHawk

[240260280z]

Just run a choke cable to hold the throttle open "a little".

[TomoHawk]

I found out the Ford units use a stepper motor, so it should be inherently proportional, if you can figure out how to get the motor to move the right amount..

Since the L28E is an electronically-controlled engine, it's more appropriate to use similar parts when upgrading. So far, it looks like the best thing is the original Bosch unit, so when you get a new one, get several.

Edited October 4, 2012 by TomoHawk

[TomoHawk]

Would be of ay bebifit if you put an insulating wrap on the device? I think it would keep it from cooling too soon.

[Captain Obvious]

I'm not an expert on the device, but I've not heard people talking about problems caused by it cooling too soon. I guess this would be more of a problem in cold climates.

I do remember someone messing with a heat wrap for some reason though... Blue maybe? He's in Canada and would certainly have more potential to need a wrap than people in a warmer area.

[240260280z]

If you want it to stay closed most of the time and close faster and stay closed just insulate it, add the later water heating device under it, and even run a hot air feed from the manifold to it like the SU carb ice preventative winter mode does.

Don't drive in the winter or on very cold days and it won't even be noticed much.

The device is just a fast idle to allow you to keep your foot off the pedal for 10-60 secs after you start it. That is it...a momentary faster idle on cold starts.

[TomoHawk]

I noticed that even on the hottest days last summer, the engine went straight to a higher idle even if you let it sit for a few minutes with the bonnet closed.

A wrap would probably be functional, but not to pretty I suppose.

[Captain Obvious]

OK. So now I've heard people talking about problems caused by it cooling too soon.

I can shut my engine off for 5, 10, 15, or 30 minutes and it doesn't have a high idle when I restart. Hmmm... Maybe yours is working fine and mine is operating oddly? Maybe it's the way I have my AAR adjusted?

When you restart after a few minutes stop and you get the high idle, you can verify if it's the AAR causing the high idle by pinching off the large tube coming off the AAR. Might be hard as a rock when cold, but you might be able to pinch it shut when the engine is warm. If the AAR is open, the idle will drop when you pinch that hose. If it doesn't change, then your issue is elsewhere.

[TomoHawk]

It's kinda weird. If you start it, it will idle down after about a minute or two. Then you drive it around a little, and when you park it, the idle goes up to 1800! I don't think it would get that cool from the airflow under the hood while driving.

An insulating cover might help. Got any suggestions? I thought a little of the header wrap ( or a wool sock?) might work, tho unsightly. You could also made a kind of a mold by pressing the thing into some putty and casting with a little glass & resin....