Manual AAR

[millarg]

Morning all,

I read a post some time ago where someone had removed there electronic AAR and converted to manual, I've searched under numerous kery word variations and cannot find, anyone done this or have advice.

My 78SC is converted to EFI, I live in a hot environment year round and generally drive short distances, meaning that the AAR is active for a lot of the time.

Any hints appreciated

[wolds]

The AAR is always active and will be in the closed position when the engine is warmed up. Since you have converted to EFI I'm not sure you need the AAR in the circuit, maybe someone else can chime in. The AAR bleeds un-metered air into the CIS when cold to raise RPM (cold idle) I believe so with the original CIS it is a necessary component. With EFI I'm not sure though. Warren

[ManniB]

Warren,

are you sure the AAR air isn't metered??? I'm pretty sure it is.

- Manfred

[wolds]

You might be right, Tony D is the CIS expert. You might be right though. Now that I'm thinking about it and after a second cup of coffee the AAR takes metered air and routs it past the throttle plate so I think it is metered. Warren

[K Sykes]

Since you converted to EFI - the metered/un-metered point doesn't matter since the air is introduced after the throttle plate and the metering plate isn't functional. You have two options - try blocking it temporarily to see if you need it to start/cold idle. The other option is to add an Idle Air Control if your EFI system can handle it and get rid of the AAR. I did the later and very happy with the flexibility it provides.

[trond]

I had the same issue and coverted to a manual heater valve and cable. Works beautifully and an easy install

Search the forum

If needed I can take pictures of my valve installed

[boyt911sc]

Originally Posted by wolds

The AAR is always active and will be in the closed position when the engine is warmed up. Since you have converted to EFI I'm not sure you need the AAR in the circuit, maybe someone else can chime in. The AAR bleeds un-metered air into the CIS when cold to raise RPM (cold idle) I believe so with the original CIS it is a necessary component. With EFI I'm not sure though. Warren

Warren,

The AAR regulates the metered air during a cold start. The slide valve is open (cold state) and gradually closes as the engine temperature and the heater for the bimetallic strip take over. I'm not a CIS expert but I just spend a good deal of time testing and experiment different conditions to understand and relate them how CIS works.

I made many mistakes and assumptions when I started learning about CIS and still making mistakes. We all make simple mistakes and as long as you learned from your mistakes, you gained experience. You don't need an AAR or WUR for an EFI system engine.

Is your car ready for the car show? I'll be back in Ohio first week of June till after July 4 holiday.

Tony

[millarg]

Thanks guys,
I tried just unplugging the ARR, but think it is open by default. Haven't tried just blocking it - will do that next.
Trond - would love to see pics of the manual valve you installed, where did you source it?
My car is a heater delete, so I'd plan on retasking one of the handles beside the emergency brake.
FYI, I installed my Bitz EFI using a 3.2 intake manifold, the AAR is planted right on the front (aft) of the engine, so easy access.

[wolds]

Tony, thanks for the clarification on AAR. OK, so your not an expert, but you're very knowledgeable. Yes, my car is ready for P2O. Got it back from Esoteric Detail a couple weeks back and she looks good. Speaking of, the mid-ohio Porsche club is hosting P2O the last weekend of July in Granville Ohio. It will be a good show. Please come out for the day and make it even better. Warren

Originally Posted by boyt911sc

Warren,

The AAR regulates the metered air during a cold start. The slide valve is open (cold state) and gradually closes as the engine temperature and the heater for the bimetallic strip take over. I'm not a CIS expert but I just spend a good deal of time testing and experiment different conditions to understand and relate them how CIS works.

I made many mistakes and assumptions when I started learning about CIS and still making mistakes. We all make simple mistakes and as long as you learned from your mistakes, you gained experience. You don't need an AAR or WUR for an EFI system engine.

Is your car ready for the car show? I'll be back in Ohio first week of June till after July 4 holiday.

Tony

[kerthunk]

The AAR is an "automatic" version of the old hand throttle. Both serve to feed additional metered air into the system (more RPMs) while the car is warming up. The AAR does it by bypassing the throttle plate while the hand throttle forces the throttle plate to be open a bit irregardless of gas pedal position.

I'm not sure what you are trying to accomplish with a manual AAR. If you simply want to have the higher idle speed while warming up the car, you could block off the AAR connections and put together a hand throttle system. If you don't need the AAR functionality at all, then you will need to plug the connections to it as it's "cold state" is wide open and therefore allowing air to bypass your throttle plate. With the AAR blocked off, you would need to feather the gas pedal to help things warm up.

[millarg]

Originally Posted by kerthunk

The AAR is an "automatic" version of the old hand throttle. Both serve to feed additional metered air into the system (more RPMs) while the car is warming up. The AAR does it by bypassing the throttle plate while the hand throttle forces the throttle plate to be open a bit irregardless of gas pedal position.

I'm not sure what you are trying to accomplish with a manual AAR. If you simply want to have the higher idle speed while warming up the car, you could block off the AAR connections and put together a hand throttle system. If you don't need the AAR functionality at all, then you will need to plug the connections to it as it's "cold state" is wide open and therefore allowing air to bypass your throttle plate. With the AAR blocked off, you would need to feather the gas pedal to help things warm up.

Thanks John, sometimes its difficult to see then wood for the trees!

So all I really need to do is retask the heater csble , anchor the housing to the fitting at the lower end of then throttle linkage and then lock the cable to the upper end.

I'm a cyclist, so should have everything I need in my cycling toolbox.

One possible problem I see is friction in then manual cable when not in use! I'll see how it goes

[kerthunk]

The hand throttle is a lever that goes on the left side of the parking brake. There is an arm on it that is pushing against a bushing that is screwed directly onto the accelerator rod as it passes the parking brake. When you pull the hand throttle up, the gas pedal will move as it is directly actuating it. I'd do a search for a diagram for the hand throttle. It is fairly simple. I put one into my '79 when I switched it over to carbs.

I'm not sure how you would replicate that action with a heater cable. I'd recommend not trying to reinvent the wheel on this. Could make for a bad day if the throttle gets stuck...

[James Brown]

wait, what EFI do you have? is there a temp sensor for air and engine temp? A stepper motor (or idle control valve) in place of the AAR valve should do it, the rest is controlled by softwear. that has been done on here also

[timmy2]

Glen,
The Bitz kit is designed to use the AAR for cold starts. Powering the AAR closes off the extra air over time (about 5 minutes) A manual slide valve will work to control the air bypassing the metered air, or you could just have it open the throttle more like the earlier CIS cars did.
The Bitz kit in it's original software format does not provide for a step controller.