Testing Aux Air Regulator

[plummerdesign]

This may sound simple, but I wish to be certain of how to test.
1984 Digijet
Testing Aux Air Regulator
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On start (warm up idle), pinching the hose; no drop in RPM.
Idle for 5 min more, repeat pinch hose; no drop in RPM.
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This indicates the Aux Air Regulator is not functioning or is not getting volts.
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How do I TEST the connector to see if there is voltage?
(I am also unsure which wire is ground; white or yellow)
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Thanks for the guidance Samba-istas.
Cheers,
Jeffery
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(Westfalia travel / camping videos at YouTube link below)
_________________
It is old and green and it makes me grin.
1984 Westfalia 1.9

[MarkWard]

Unplug the auxilary air regulator wire connector. Put a volt meter across the two leads. With the engine running it should have power. It may work with just the key in the run position, but I don't have the wire diagram in front of me. If you don't have a live circuit, then connect the volt meter to ground, one of the two should have 12 volts. Then check for ground. Connect the voltmeter to power and probe the wire connector, you should get a ground off of one of them. You can also use an old fashioned testlight.

[wecm31]

I like the description for testing the wiring harness...

Is it possible to bench test the actual AAR?

I bought a new one a few months back and tried just to apply 12 v
to the two pins on the body, nothing happened. Should it cycle even
if the polarity is wrong?
_________________
Gerald P
1985 Vanagon (Betty) & 1985 BMW R80RT (Wilhelm)
vintage boxers!!

Gone are the days we stopped to decide
Where we should go, we just ride:)

[MarkWard]

Yes you can bench test it with a 12 volt power supply. With the regulator at room temp, look through it, it should be fairly wide open. There is a cam wheel that as the regulator warms up closes the opening. So, apply 12 volts and a ground to the regulator and watch the opening close. If it does, you know that it is working. These are factory set, but if you get creative you can adjust them. I don't recall the exact steps, but there is a tiny screw and a locknut with yellow paint I believe.

The auxilary air requlator is just that. It lets additional air into the intake during warmup for an improved warm up idle. Unfortunately it is mounted under the plenum which makes it hard to check on the engine even with a flashlight and mirror. Last time I needed one they were NLA, but these regulator were used for years on Rabbits, Dashers, and Jetta's pre 83.

[WestiCoast]

There is a small amount of adjustment that can be made on these. There is one screw on the whole part, that screw is the adjustment. You don't need to take the screw all the way out, only loosen it. It will move only about 1/8 inch. The way these are designed they work with or without the power circuit. It’s bolted to the engine so as the engine warms up it will close the valve. If you take it off the engine you can throw the whole thing in the freezer for ten or fifteen minutes and it will open. If you put it in a 200 degree oven it will close. You can test that the internal warming element is working with by wiring it directly to your battery or some other 12v power source (I used my jumper box). Our Digijet vans are usually a little sluggish till they get fully warmed up. I think a big part of that is the one wire O2 sensor. The three wire O2 sensor heats up faster than the engine. Even sitting idling for a while can cool the O2 sensor enough to read incorrectly.

[plummerdesign]

Thanks for the feedback!

Used the simple testing light method and found power IS going to the aux air regulator. Will try the bench testing procedures as shared above. I especially like the 'freezer' option

Cheers,
Jeffery
.
(Westfalia travel / camping videos at YouTube link below)
_________________
It is old and green and it makes me grin.
1984 Westfalia 1.9

[plummerdesign]

Following up: Removed the Aux Air Regulator and put on bench. Hooked it to 12v supply.

Before adding power it had a TINY opening for air passage.
After applying power the opening closed completely within moments.
With power off, the opening did not reappear within 15 minutes, SO it was placed into the freezer.
After 20 mins it had opened to reveal a slightly larger air passage, maybe 1/3 of the cam. Will try to adjust some and lubricate the cam. Seems this unit SHOULD open without being in the freezer. Freezers are for ice cream.
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Reason for tinkering... Had some poor cold start drivability, as the bus would stall easily in first few minutes. Pinched the hose to test, no change. Thus the investigation.

Cheers,
Jeffery
.
(Westfalia travel / camping videos at YouTube link below)
_________________
It is old and green and it makes me grin.
1984 Westfalia 1.9

[hdenter]

It's hard to say. How cold was it when you stared? How warm of a day was it when you removed the power? Did you tap it or vibrate it a little to simulate being mounted in the vehicle?

That it moves is a good sign. Have you sprayed it with some cleaner through both vac openings to make sure that it can move freely? Even a clean one could stick a little if the temp change is relativley small and it is a little dirty.

I have a tempermental one on my '84. But, when it sticks open I have the clasic symptoms.

Starts and idles great when cold in the morning
Once warm, the idle surges as if there is a vacuum leak
If I go back and pinch off the air hose from valve, the idle goes back to normal
When I release the hose it surges again.

Try it agin, this time put it in the freezer for a little while and tap it a little before hooking up the 12v. After several minutes, remove the power, tap it again and see what the possition the valve is in. Since it moved a little I suspect the element is good, just a matter of determining if the mechanical parts are free to move.

Do you have the same idle problem I described? Why do you suspect the air valve is bad?

hans
_________________
'79 triple white convertible bug
'84 sunroof vanagon
'85 weekender

[t3 kopf]

if the 80s models rabbits and such had a similar aux air regulator, is it interchangeable with the digijet one? or any any other ones interchangeable?
_________________
'90 Carat w/ '95 phase 1 EJ22 OBD2 conversion

[tencentlife]

[plummerdesign]

This bogus internet 'wisdom' has been deleted.
Cheers,
Jeffery
.
(Westfalia travel / camping videos at YouTube link below)
_________________
It is old and green and it makes me grin.
1984 Westfalia 1.9

[tencentlife]

This person quoted may know how to fiddle with a simple thermal valve but does not understand its function in the FI system. The AAR bypasses metered air, therefore it can have no influence on mixture and therefore no influence on engine torque one way or the other. He seems to be burdened with a commonly held misconception that the AAR leans out the cold idle mixture, the opposite of cold idle strategy and one that if it were true would not produce a reliable cold idle. I have seen the same notion asserted here again and again, and even had people insist it was true even after their misconception was explained to them clearly. That says a lot more about human psychology that it does about fuel injection.

The same misconceptions adhere to the cold-start valve used in K-jet and pre-Digifant L-jet systems, that it modifies cold idle mixture, which it does not. It derives its power supply from the starter motor trigger circuit and only operates when that circuit is energised, meaning only during actual cranking. Digijet and -fant are late variants of L-jet, and thankfully in both the cold-start valve was eliminated, but unfortunately Digijet still used the AAR as a cold idle speed boost. Cold starting injection quantity and subsequent warmup mixture are indexed solely according the the coolant temperature reading returned by the Temp2 sensor. The "dumb" AAR and the later, more complex feedback-driven ISC systems act as throttle bypasses, their effect is the same as cracking open the throttle valve to increase idle speed, and the only influence their action has on mixture is the same effect that would result from cracking the throttle open a bit, a slight increase in the AFM vane position with a small increase in the injection quantity proportional to the increase in measured air mass. This does not constitute a modification of mixture, it is the normal scaling of injection quantity according to air mass. None of these things has any effect at all on engine torque. Period.
_________________
Shop for unique and useful Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/
also available at VanCafe.com!

Please don't PM here, I will not reply.

Experience is death to doctrine.

[t3 kopf]

[hdenter]

If you don't want to mess around, here is a new one.

http://www.jcwhitney.com/bosch-auxiliary-air-valve/p3047511.jcwx

Hans
_________________
'79 triple white convertible bug
'84 sunroof vanagon
'85 weekender

[hdenter]

So... You have to run the JCwhittney part as an 87 Nissan 300ZX, but it looks right. As Tencent said, they are all interchangable.

Hans
_________________
'79 triple white convertible bug
'84 sunroof vanagon
'85 weekender

[whafalia]

Searching bosch auxiliary air valve on amazon gets a bunch of results that all have the same representative photo and different part #s and prices, a couple below $60, closer to reasonable!

Mine's worked for a couple of periods, the high idle made me feel I was in a modern car, it was cool! I think the last time was its last gasp though, it's dead. I don't seem to need it though.
_________________
84 westie 2.2 w/ digijet, AT

[plummerdesign]

Well alright, seems Area 51 never had any aliens and the pithy bit about adjusting the AAR is just as bogus. Internet wisdom eh?

Thanks for the correction, I have removed the erroneous quote so no other souls go wayward. In the meantime it is good to have a source with JCW, cool.
My AAR is working much better after a proper cleaning and lube. Seems that is the case for many things
Cheers,
Jeffery
.
(Westfalia travel / camping videos at YouTube link below)
_________________
It is old and green and it makes me grin.
1984 Westfalia 1.9

[tencentlife]

Yeah, better not to have the nonsense where someone will see it, parrot it elsewhere, and then it will come back here with people arguing something bogus all over again.

The AAR is an incredibly simple thing, as I said it's a dumb valve. It has a mechanically predetermined "thermo-time" function a lot like the thermo-time switch that regulates whether and for how long the cold-start injector would spray on older L-jet and K-jet systems.

The passive test uninstalled is to look thru it when it is at room temp or colder to see if there is a visible orifice (it's oddly shaped and generally opens at most about 60% of the sectional area inside the valve), and that the orifice closes completely by warming the valve up.

To test when installed, you just pinch off the air feed that goes thru the AAR when the engine is cold idling and if idle speed drops, there is an orifice. Then do the same when the engine is idling fully warmed up and there should be no speed change, indicating the orifice is closed.

The electric test is to verify that there is 12V across the power supply connector pins (power is on whenever the engine is running), and that there is a circuit thru the AAR heater coil with about 30ohms resistance (I'm going from memory on the ohms number but the question is really whether there is a circuit or not). Alternately, with the unit uninstalled, the orifice that is visible cold should close up in about 5 minutes of having 12V put thru the heater circuit, polarity doesn't matter.

It can have an open heater circuit but still work passively by absorbing heat from being bolted to the engine, so even if the electric-heating test fails, cooling and warming the valve may still show it works, using such a valve would just allow the engine to idle at a higher speed for a bit longer than if the electric heating feature were working.
_________________
Shop for unique and useful Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/
also available at VanCafe.com!

Please don't PM here, I will not reply.

Experience is death to doctrine.

[jerryherb]

So the below statement is completely wrong, read at your own risk, it may make you dumber
______________________________________________________________________________

The functional AAR DOES alter the mixture during the first few minutes of cold start. As the T2 sensor tells the ECU that the engine is cold, the ECU increases the duration of injector spray pattern making the engine run rich (basically chokes on fuel if AAR is closed). ECU does not know the status of the AAR (no signal from AAR to ECU), but expects more air to be present when more fuel is provided to increase the idle for the warm up period. AARs function during that time is similar to unscrewing the idle screw a few turns and screwing it back in once T2 tells ECU engine is warm. Once the engine is warm (per t2 input) the ECU cuts down on fuel delivery and it expects, per predetermined AAR closure time, that air supply is also reduced. If AAR is stuck open engine runs great at cold idle but too lean when warm. if stuck closed it runs poorly at first, but then fine once warm. It all has to do with the mixture (with throttle body closed and tps switch adjusted properly) and the ECU does not know whether AAR functions as it should. I also suspect that O2 sensor starts adjusting the mixture before the engine is fully warm. AAR stuck completely closed causes too rich of a mixture which the ECU tries to compensate for by cutting down on the fuel supply which results in lean surges when not fully warmed up. Thats why the engine idles better with the O2 disconnected during the warm up period but lacks pickup in the first minute or two when AAR does not function as it should.

[tencentlife]

When you find yourself having to argue so elaborately, it's time to step back and apply that complicated little thing called "Ockham's Razor".

Throttle bypass systems are mixture-neutral, they merely route metered air to bypass the throttle and as I've said about five thousand times they have precisely the same effect as opening the throttle slightly to raise idle speed. Period.

Don't teach your grandma to suck eggs is another old saying.
_________________
Shop for unique and useful Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/
also available at VanCafe.com!

Please don't PM here, I will not reply.

Experience is death to doctrine.