The AAR is stuck open on my 2.0L. In fact, when I connect it to the power source it pops the fuel pump fuse (25A) I put a clamp on the hose so now I have to feather the throttle at stops until the engine is warmed up. Obviously, if I take the clamp off then the engine will idle really fast once op temp is reached.

I found a "spare" unit but it, too, is stuck open. Why can't they stick closed? So, what is there to replace it? I tried the 914 on-line part stores no no avail. AA was a PITA to "flip" thru their on-line catalog (yeah...whatever) and I get bored and gave up looking thru it. The device looks exactly like the unit I had on my previous Type 3 automatic -- which served the same function and was powered by the coil. So I got to thinking, the other units out there, for cars like water-cooled VW engines, use a similar device, just a little more aerodynamic looking Would one of those (less expensive) units work? Can someone point me to a place that does sell AAR's for our cars (not a "I think such-n-such sells them")? What have others done to fix or replace their failing units?

Thanks

N L A

Some guy who lives in one of those unnamed North Western states has some, but he'll make you do all kinds of bad things, then pay shipping..



Trick... don't connect it to power... the engine heat will eventually (few extra minutes) make it close. Take it out, and clean it with some PB Blaster, then remount that puppy, and enjoy.


M

Yeah, I know engine heat will do it as well. I wonder why they don't use the pure mechanical units like those on the VW manual transmission engines (spring is located on top of the case, near the oil breather, where oil can splash on it)?

Well, I'll see about busting open the 'replacement' unit that came with the car and fiddling with that. I did squirt PB Blaster in it and washed it around but no luck One web site said to pop it in a vice and pry back the body to get to the innards for fixing it. I guess we'll see

don't have an answer but
what's this AAR... what's it do

Auxiliary Air Regulator. It lets air bypass the (closed) throttle plate when the engine is cold. That raises the cold idle RPMs somewhat, and more importantly keeps the cold idle RPMs from being "zero".

ACN, it sounds like the heating element in your AAR has shorted to the cannister. Check the resistance from the plug to the housing of the AAR; it should be about 13 ohms. Bet you find more like zero. If that is the case, opening it up is the only way to fix it--you can pull out the coiled "resistance wire" that's in there, and replace it with about 13 ohms worth of 1-watt (or 1.5 watt, if they make those) resistors. They should heat up at pretty close to the same rate as the original wire did.

You could also adapt a later car's "cold idle air bypass" mechanism to the 914, if you were so inclined. If the bypass is a simple heated valve like the stock part, then you just have some hoses and wires to hook up. Of course, it may let the wrong amount of air through at various times during the warmup, but that'll just mean the engine will idle a "little funny" for those first few minutes of driving, which is probably no big deal.

There's a new 914 owner over on the Yahoo group who replaced the AAR with a manual version (he will be installing a "choke cable" for it Real Soon Now) without even bothering to test his AAR.

But I'd still try to fix the original part if you can.

--DD

sounds like you have a D-jet. maybe you could look into converting an L-jet AAR to D-jet. if i recall, L-jet AAR's are still available.

QUOTE

sounds like you have a D-jet. maybe you could look into converting an L-jet AAR to D-jet. if i recall, L-jet AAR's are still available.

Yep, thats what I did. Works fine, problem is, you need a 2 pin connector (just like fuel injector connector). Back when import car parts stores were around I would get stashes of these plastic connectors and the electrical contacts inside them. Prolly cant do that anymore, but auto atlanta sells them with rediculous mark-up.

plastic connectors and wires are available from Beck-Arnley (a god send for me)

DD, you have the part numbers, you gave them to me at one point....(i could use them again myself)

4-pin plastic connector
5-pin plastic connector
wiring inserts for connectors
pin release tool

b

Thanks guys, and DD for a way to electrically test it.

No, no choke cables for me! I'll adapt some other unit...not crazy about putting more holes in the firewall or having to fiddle with additional controls.

QUOTE (Air_Cooled_Nut @ Oct 1 2005, 03:06 AM)

Yeah, I know engine heat will do it as well. I wonder why they don't use the pure mechanical units like those on the VW manual transmission engines (spring is located on top of the case, near the oil breather, where oil can splash on it)?

AND WASTE A CHANCE TO USE A PIECE OF BROWN WIRE!? ARE YOU INSANE?

-fffffufff...-


M

Find the part number for a 924 AAR, it's a two-plug unit. I don't know if it's the same as L-jet but the connection is the same. They're fairly inexpensive as well. It's a typical Bosch unit.

Worst case scenario... Disconnect the CSV and plug the hoses for the AAR, manually warm-up your car with the gas pedal (a-la-carbs).

Took apart the replacement AAR. Ohm reading was 13, measured from the pigtail connector to the AAR housing. This was an electrically good unit. The one in my car reads 0.5ohms, thus most likely the heating element broke and is touching the AAR housing.

The bimetalic spring is easily removed and doesn't unwind like a traditional spring. Dropped some oil in the AAR lower hose connection as well at on the spring shaft and turned the shaft with some pliers. There was some minor initial resistance then it rotated. Not very smoothly, there are some rough-feeling spots but after working the shaft back-n-forth it moved more easily.

Adjusting/retaining spring screw. In the setting shown, the spring will open more quickly. If the spring is adjusted to the opposite side of the slot, it will open more slowly.

For my application I removed the ceramic cup, fiber washer and pigtail. Just a picture to show how it looks. To remove the ceramic cup the two rivets on the bottom of the AAR housing need to be drilled out.

I removed the ceramic cup and bits then put the top part (the spring and holder) back onto the housing. A couple of tack welds to hold it together then filled the seam with hi-temp silicone sealer (the copper-looking stuff). The housing didn't want to weld back together very well and left a white silky residue so I think the housing is zinc'd or something. It is ferrious (magnetic). I left the holes where the rivets and pigtail are located at the bottom of the housing open. This will allow oiling if it should need it plus let heat in and moisture drain since I'm not sure how good my silicone seal will hold up.

Haven't had a chance to test it as it's raining quite heavily outside and my door/window seals ain't the greatest...plus the hood is still off. Cold engine started right up and idled so I know that cold-starting is working fine. The real test will come once the engine is at operating temp as the AAR should completely close up and keep the idle from hitting the 2000+rpm like she previously did I'll report back when I can on how it works.

Cool pics ! It would be great ot see a gallery of parts like this one, either dismembered or intact (for "What does the AAR look like?" type posts).


BTW, did you do a test of the AAR resistance ? My AAR was killing my engine b/c the wire to it was dry and cracked, and shorted to the engine. Kept blowing the fuse to the ECU. Finally tracked it down when the fuse didn't blow, and I saw an awesome display of sparks shooting out from down there. Currently, I don't have an AAR. We'll see if I bother with it when cooler temps set in...

Just came back from a test run -- failure

I thought the stock location would soak enough engine heat but my whole engine isn't very hot at all. I drove her for about 15 minutes, and on 45-55mph zones, up into the rpms, so I know she was at operating temp. The engine just idled fast so I had to clamp the hose shut to get the idle back down to stock.

Looks like the spring element needs to be in constant heat which I now understand why there's either an electric heating element constantly heating it or, in the case of the manual tranny FI VW engines, the element is in the engine case constantly getting splashed with oil.

Oh well, nothing ventured nothing gained so back to the drawing board

one word: remote control servo drive auto-manual HAR

(human air regulator)


M

PM Cap'n Krusty. He has 2 working AAR's on the shelf at the shop. Dunno what he wants for 'em.

Hey Air Cooled Nut,


Your pics inspired me to rip my AAR open. Mine had been working okay, but the wire was so old & cracked the insulation didn't do its job. Like a goober, I yanked on it, thinking that that *must* be a connector in there. No, it is not. So anyway, my task was just to solder in a new wire.

I never looked at my AAR too closely. From your pics, though, I realized that the unit is sealed by a "squish" seal (I'm sure the Germans have an impressive word for it...) The bottom is a can with an embossed lip, and the top is a flat flange. When the flange is in place, a machine of some sort squishes the lip tightly against the flange.

To open, I put AAR gently in a vise, and started hitting the seam with a chisel and hammer. The chisel was digging under the lip, pointing radially outwards. Problem w/ this method is that the tubes of the AAR are in the way. But once the lip is curled up in one spot, I found that the metal is soft enough to pry up w/ a flathead screwdriver.

For my job, I drilled out the contact where the wire used to be, using a very small bit. The shavings that came up were copper. Bonus ! I stuck the stripped end of some fresh new wire up from below, and soldered it in place -- the fresh drilled copper made a good clean surface to bond to.

When I was done, I put the top (flange) into the bottom (cup) and started squishing the seal shut. At first, the squishing has to be radially inwards, to reduce the diameter of the pried-open part. Then, the blows (I used a ball peen hammer on top of the vise) need to go downward, to crimp the lip shut against the flange. In practice, it's really sort of a rolling process. Anyway, I'm sure the joint isn't waterproof, but it did get pretty tight -- with quite strong pressure from each hand, I can't make it rotate. Just to be sure, I'll probably smear some goo on it.

What I love about this job is that it's one of those old-world things you could do on the side of the road, if you had to (but you don't...) One reason I got my 914 was to counterbalance my other car ('97 Saab 900 turbo) that is so friggin' complicated, that only a licensed dealer w/ the right computer can even start to mess with it.

Anyway, as your pictures show, there are two halves to the AAR : the electrical half (a simple heater) and the mechanical half (coiled up bi-metal spring that rotates a valve. After doing this job, I'd encourage anyone with AAR woes to open theirs up and try giving it a fix. The stuck valve can't be much more than you found - twist it back and forth a little, and maybe lube it.

The electrical half isn't so bad, either. The heater element has about 13 ohms of resistance, which dissipates 11 watts (P=v^2/r). Anything with around 13 ohms resistance will work, but it must be able to stand up to a steady state dissipation of 11 watts (plain electroniconic-store resistors are only 1/2 watt or so, typically). The wire that's in there is probably either tungsten or nichrome. If you can get your hands on either, cut a length that measure 13 ohms or so, and wrap it into a coil around a nail or something. An easier method might be to clip a section out of an old toaster -- you needed to go to thrift store anyway, you CSOB.

Anyway, I'm off for home (laundry, etc.) and I'll try to take a snap of my "new"
AAR and post it tomorrow.

Cheers,
Jeff

Jeff, that's exactly how I opened up my old AAR.

I thought the power was only ~1 watt? Hmm, you might need some really beefy resistors if it's actually 11 watts!!

13 ohms worth of resistors (that can deal with the current!!) will heat up just about as quickly as the stock "resistance wire" did--so you can swap in plain resistors instead of the fancy wire stuff if you need to.

--DD

Hi Dave,

Yeah, the power is around 11 watts (v^2/r = 12 * 12/13), which is a fair amount of power for normal resistors. But generating that much heat is the whole point -- it's kind of a mini toaster oven in there ! Ordinary resistors usually go up to like 1 watt, so a string in series/parallel would work but be kind of bulky; might not fit.

Anyway, to show off my handiwork (and my cat's butt) here's a couple of pictures.

and the other side, not butts about it ...