AAR..Has any one experimented with the orifice size

[gorskined]

I have newly rebuilt 76 row turbo. Far weather driver In a 80 sc widebody . The original 76 had the hand throttle to compensate for starting while cold . I can't add the hand throttle because I replaced the original tunnel lines with an6 lines and the hand throttle will not fit, lines hit the hand throttle arm. So I figured I would add a AAR valve . I did but the connector off the I/c is a little smaller than AAR inlet hose so I'm assuming I may have a slight restriction from the original design . That being said the house is still huge compared to the internal opening in the AAR valve when cold.

Before the AAR was added again not originally designed for a 76 it was crank for 5 second stumble sputter the idle around 500 until warm then a sold 950... With the new AAR added little less cranking slight stumble and sputter 750 rpm then a sold 950 .. I'm looking for the cold crank fire up with the 1500-2000 rpms ... As the AAR is closing off back to the 950... Logic would say make a bigger hole in the AAR to bypass more air. .. just wondering if anyone has screwed around with this . Before I ruin a perfectly good AAR.

Thanks in advance
Regards Ned

[Alan L]

My cars have never fired up at 1500+ rpm. Not sure I would want them too. Sounds to me like you are close to where you need to be. I doubt the hose will be a restrictor - like you say - the gap in the cold AAR is not big. Just an additional bit of air for the cold mixture.
If you really wanted to experiment, you could probably prise the disc open a bit more for a test. It is a spring/bimetallic finger system. Realtively easy to manipulate if you pull it apart. But just for a basic test, I would be thinking if somehow wedging it open a bit more. Something like a stout wire loop or similar just to hold the slit open a bit more and see what happens for the cold start.
Alan

[mark houghton]

Mine typically starts up stone cold at around 900 rpms and settles in to 950'ish when warm.
Years ago I posted something on where to drive a pin on the side of the AAR to open it up a bit further for higher idle, but if you overdo it then you have to open it up to reverse what you did.
As Alan said, I think you're close to fine where you are. Just keep you foot on the gas for the first 30 seconds or so if you want.

[908/930]

One other snag with wanting 1500-2000rpm cold is when you drive a short distance then stop the car for a short time for fuel or whatever, when you start back up you will be at 1700-2200rpm until the AAR electrically warms up.

[mark houghton]

Originally Posted by 908/930

One other snag with wanting 1500-2000rpm cold is when you drive a short distance then stop the car for a short time for fuel or whatever, when you start back up you will be at 1700-2200rpm until the AAR electrically warms up.

Yep, annoying in and of itself.

[gorskined]

all very good points .. My AAR takes about 2 minutes to fully close. very close to the same amount of time the wur takes to heat up . not sure how fast it cools or if a hot engine bay will keep it closed when off . So 900rpm is the norm, all the turbos i typically see when i take my 356 to Porsche shows. The guys stand outside their window turn the key and it fire right up very crisp rumble right around 1500. i just assumed that was the norm. i would be interested in finding more info on that adjusting pin to advance the internal AAR slide a little more forward going to search the forum later today when i get some time.
as always thanks for the assistance guys
Regards Ned

[908/930]

My 1987 engine starts right up as soon as the starter engages, possibly the ignition timing being pulled back for emission purposes warm up helps with this? The cars that you are seeing start up and idle at 1500rpm likely still have a warm engine. I think with the AAR adjusted correctly a cold startup will run at normal hot idle speed, but it's not really that accurate a device.

[mark houghton]

Wish I could point you to a more definitive thread. Last time I chimed in on this adjustable AAR topic was back in 2013 but not much help. Someone a bit later did post a more elegant mod, just need to search a bit.
I would agree that what you've seen from other 930's is likely high idle from an already warm car. One would think that engine heat soak would be enough to close off the AAR, but in reality it's the internal heating element that does the trick...which is why an already warm car after being shut down for a few minutes will idle high on restarting.

[RarlyL8]

Idle speed changes for various conditions are precisely controlled by the myriad of CIS, ignition, emission and idle control devices. If any of these devices are removed or become inoperative it will affect idle control specific to their function. This includes air injection and the various throttle bypass and thermol time valves. When these cars were brand new you hit the key and the idle popped to around 1200rpm then slowly dropped to 950rpm according to the ambient temperature and engine temperature. This can be duplicated with everything removed (minus the auxiliary air regulator) by adjusting the AAR. We can offer this conversion on an exchange basis.

[spuggy]

Originally Posted by mark houghton

One would think that engine heat soak would be enough to close off the AAR, but in reality it's the internal heating element that does the trick...which is why an already warm car after being shut down for a few minutes will idle high on restarting.

I knocked the JT connector off the AAR one day and didn't notice. Can confirm that heat soak from the motor had no effect - my hot idle stayed @ 1700 RPM until it was re-connected. (Cold idle never that high, only hot re-starts).

I seem to recall John Walker commented once that some 930 owners consider this "obnoxiously high" and swap in an SC AAR instead, resulting in a lower idle on hot restarts while the AAR is heating up.

[Alan L]

I have an SC and I don't recall hot idles over 1500. Not close really.
I did have a weird issue a few yrs back - when it would do this. Between 1500-2000. Til I got on the move and it dropped at next gear shift. Drove me bonkers. Was very glad when it went away.
Alan

[gorskined]

So i did play with the aar over the weekend . i took it apart and made some adjustments i was able to get a crisp 1250prm cold start no hesitation Then a slow 4-5 min drop to the 950rpm.
i was very please with the outcome . . I did notice the extended idle when i shut the car down for even a minute. it took 2+ minutes to regulate back to 950 just like everyone mentioned .. when i clamped off the hose to the aar it immediately held a perfect 950 after the minute shut down. while bench testing the aar i did notice the last 1/4 of the closing took the most amount of time and quickly started reopened seconds after the aar was deenergized.

. .. i have read about the cable activated systems some people use to close off the aar a great idea . i would rather use an electronic valve .. can anyone recommend a 12v 5/8" actuated valve .( thinking possibly a modern heater core valve )
On an interesting note. when i started the car to leave for work 1200rms. i quickly walked around to the back and clamped off the aar hose the rpms dropped instantly to 950 And ran like a dream . So far from what im gathering, i only need about about 30 seconds of extra air through the aar.
im contemplating adding a timed rib relay set to 30 seconds+- to energize a valve to shut down the air to the aar to automatically and close off the air 30 seconds after start. . wiring should be simple, i can incorporate everything directly off the aar.

one other advantage to the 1200 rpm start is I don't need to blip the throttle to shut off the red generator light.

update i found a Audi transmission solenoid cooling valve and a delay off solid state adjustable timer they looks to check all the boxes . i will update one i have everything installed.


Regards Ned

[mark houghton]

They're pretty basic and as you found easily adjustable once you get inside them. As I said earlier, mine idles at about 900 initially and hunts pluss or minus 50 rpms for the first maybe 45 seconds until the WUR warms up enough to start exiting the lower control pressure and richening effect. That said, I wouldn't mind having a slightly higher initial idle...a bit more air to compensate for the rich mixture, but I just live with it.
Installing a timed solenoid sounds like something I would do! Go for it...

Or, install a switched alternate power source direct to the AAR that your could switch on after shutting down the engine, to keep the heating element energized and warm.

[Alan L]

Originally Posted by gorskined

So i did play with the aar over the weekend . i took it apart and made some adjustments i was able to get a crisp 1250prm cold start no hesitation Then a slow 4-5 min drop to the 950rpm.
i was very please with the outcome . . I did notice the extended idle when i shut the car down for even a minute. it took 2+ minutes to regulate back to 950 just like everyone mentioned .. when i clamped off the hose to the aar it immediately held a perfect 950 after the minute shut down. while bench testing the aar i did notice the last 1/4 of the closing took the most amount of time and quickly started reopened seconds after the aar was deenergized.

.Regards Ned

I would say you have got it pretty well nailed. PlentyCIS 911s likely not cold starting as well as that.
Alan

[gorskined]

update
I finally got around to putting in the Audi heater solenoid control valve part # 5q0122093. its directional so i installed it directly behind the AAR. i originally installed with an automatics time delay relay to close it. I wasn't happy with how it functioned so I removed the time delay .
I ended up pulling my defrost relay and using the 12v power from the plug to trigger the coil in a 5 pin 12v universal relay.
I took the 12v from the wur to run through through the common switch terminal on the relay and put the solenoid hot wire on the normally open terminal this way when i pull out the defrost knob it send 12 volts to the normally closed relay coil from the defrost switch it energizes the circuit and opening the relay contact to the solenoid allowing air to flow threw my AAR .
Basically when I turn on the defrost circuit it deenergized the solenoid. The solenoid is normally open. there is no power drain because the defrost only has power when the key is on and the wur only has power when the fuel pumps are running.

I have never used my rear defrost and don't intend to. The defrost relay is still in the car just not connected . The plug is under the fuse panel not connected. i used a spade connector to access the switched 12v directly from the plug and insulted so it was secure.

When I start the car cold, i pull out the Green rear defrost switch and it illuminates (i was happy to see that works ). The car fires up with a crisp 1200 +- 50 Rpm if i let the aar do its thing it never fully closes it backs down to 1000+ or -50 never the same twice . I played with the opening to get more air to get the higher rpms during cold start. When i close the solenoid the engine idles at a perfect 950 . This also gives me the option to only use the AAR during a true cold stat ( no restarts with high idling)

I did notice that once the solenoid is in the closed position while the car is running the vacuum pressure keeps it closed. once you close it you cant reopen it by accident until you shut the car off. (also another good thing )
now the only thing I need to figure out is what to paint on the face of the green illuminated defrost knob.

im very happy with how it turned out . The wiring is not permanent , I will making a new wiring harness for all my addons once im sure, I have everything the way I want it .

[mark houghton]

I love a good hack!
So your AAR otherwise is still functioning, but your issue all along was wanting a higher cold start idle, correct? Perhaps look at blocking the plate/window inside the AAR wide open and just turn the solenoid on and off as needed. And/or, leave the 12v to the AAR permanently unplugged so it never heats up and closes.

[gorskined]

Originally Posted by mark houghton

I love a good hack!
So your AAR otherwise is still functioning, but your issue all along was wanting a higher cold start idle, correct? Perhaps look at blocking the plate/window inside the AAR wide open and just turn the solenoid on and off as needed. And/or, leave the 12v to the AAR permanently unplugged so it never heats up and closes.

yes my issue was my 76 3.0l originally had a hand throttle to compensate for cold starts. My 80 sc car doesn't have a hand throttle and i couldn't install on because i have oversize an6 lines in my tunnel . When I cold started my car it hesitated and chugged ( embarrassing )
i installed an AAR to help with the cold start and eventually adjusted it to get a crisp start around 1200. but in the full closed position the rpms would wonder sometimes 950 other times 1050 hence the installing of the solenoid hack.
I did try it with the AAR unplugged it worked good as expected but started to creep up as the engine started warming up. Leaving the AAR functional as engine warms up the RPMs starts to slowly step down the rpms. When the rpms reach about 1100 i push in the button to energize the solenoid,. the engine drops to a solid 950rpms.
its actually quite nice, sounds professional and no high idle warm starts.

i spent a lot of time with the aar over the last month. even though as previously mentioned where its been said that the ambient engine heat doesn't affect the aar opening, it does .
a 50 deg garage in the morning had my AAR 3/4 of the way open and a 70 deg garage has it about 1/2 half way open. 100 deg engine bay is still 1/2 open . and 1 minute after running on a hot engine bay just a very small opening. a lot of thought and engineering went into that little odd shaped orifice. the AAR deflection curve is defiantly non linier. To fully close the AAR, the inside of it must be awfully hot.
Hot enough to make smoke . ( i lubed every thing when i took it apart and got oil on the element ) though i burnt it out at first.

[mark houghton]

Certainly ambient temp would have some effect, as you've demonstrated. Good job, you are now the forum's resident expert on all things AAR!

[Alan L]

"i spent a lot of time with the aar over the last month. even though as previously mentioned where its been said that the ambient engine heat doesn't affect the aar opening, it does .
a 50 deg garage in the morning had my AAR 3/4 of the way open and a 70 deg garage has it about 1/2 half way open. 100 deg engine bay is still 1/2 open . and 1 minute after running on a hot engine bay just a very small opening. a lot of thought and engineering went into that little odd shaped orifice. the AAR deflection curve is defiantly non linier. To fully close the AAR, the inside of it must be awfully hot.
Hot enough to make smoke . ( i lubed every thing when i took it apart and got oil on the element ) though i burnt it out at first."

You can adjust it to set slightly differently - ie fully close at a lower temp. You have probably figured that out. But what happens over time is the bimetallic finger gets a permanent warp/set in it - due to the constant load on it - in one direction.
Pretty sure I adjusted one of mine some distant time past.
Alan

[gorskined]

Originally Posted by Alan L

"i spent a lot of time with the aar over the last month. even though as previously mentioned where its been said that the ambient engine heat doesn't affect the aar opening, it does .
a 50 deg garage in the morning had my AAR 3/4 of the way open and a 70 deg garage has it about 1/2 half way open. 100 deg engine bay is still 1/2 open . and 1 minute after running on a hot engine bay just a very small opening. a lot of thought and engineering went into that little odd shaped orifice. the AAR deflection curve is defiantly non linier. To fully close the AAR, the inside of it must be awfully hot.
Hot enough to make smoke . ( i lubed every thing when i took it apart and got oil on the element ) though i burnt it out at first."

You can adjust it to set slightly differently - ie fully close at a lower temp. You have probably figured that out. But what happens over time is the bimetallic finger gets a permanent warp/set in it - due to the constant load on it - in one direction.
Pretty sure I adjusted one of mine some distant time past.
Alan

pretty sure that exactly what happened warped over time and I over adjusted to get a good start, now it wont fully close off . The aar takes care of the air for the cold start and The solenoid makes sure nothing bypasses once warm . The only thing that would make it easier if i was able to find a normally closed solenoid. then it could be a direct wire from the defrost switch no relay or sharing control power with the wur.