AAR valve?

rcrgrl · 05-10-2006, 06:20 PM

So my 73 1.7 is idling high. I asked on the club board, and i know there was answer or two (dave d?) but apparently didn't get back in time

I think maybe the AAR is stuck open, but how do i check that? And the intake for the decel valve is creating suction and when i cover it the idle does drop, which is what its supposed to do right?
what else should i check. and yes i've checked the hoses. twice. i think too, my dad's mechanic says it has a 911 part in the FI, but oh heck if i can remember which one.....

crresind · 05-10-2006, 07:54 PM

Just like the decel valve, you can plug the hoses at various points to isolate the problem. The system only needs the AAR for warmup, so it could operate without it completely.

SirAndy · 05-10-2006, 08:00 PM

Quote:

Originally posted by crresind
The system only needs the AAR for warmup, so it could operate without it completely.

i agree. a stuck open AAR will result in a high idle when *warm* but somewhat normal operation when *cold* ...

easy check, with the engine warm, take off the hoses from the AAR and plug them. if the idle drops down to normal, your AAR is stuck open.

if you don't care much about cold running quality, you can as i did and just eliminate the AAR altogether. simply remove it and plug the two hoses.
with the engine cold, i need to keep the foot on the throttle, otherwise it'll die, but after a minute or so, the car runs and idles just fine.

Andy

rcrgrl · 05-10-2006, 08:29 PM

thanks guys. on further 'testing' there is a valve/switch that has intake from the air filter then has a hose leading to each head. when i cover the intake, the idle drops nicely. the haynes manual calls it a flashback valve. what what?

SirAndy · 05-10-2006, 08:35 PM

Quote:

Originally posted by rcrgrl
thanks guys. on further 'testing' there is a valve/switch that has intake from the air filter then has a hose leading to each head. when i cover the intake, the idle drops nicely. the haynes manual calls it a flashback valve. what what?

that should work the other way. it's supposed to "vent" the heads into the air filter.
there's also supposed to be a hose from the oilfiller neck in that same configuration.

it sounds like you got a intake air leak somewhere ...

Andy

rcrgrl · 05-10-2006, 09:23 PM

there is no hose from the oilfiller neck..? i think the system has been "improved" by the PO. but then i'm not familiar with it - yet. so i keep looking for an air intake leak, but i'll be damned if i can find it. of course i own 2 914's so i'm already damned !

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Quote:

Originally posted by rcrgrl
thanks guys. on further 'testing' there is a valve/switch that has intake from the air filter then has a hose leading to each head. when i cover the intake, the idle drops nicely. the haynes manual calls it a flashback valve. what what?

It is also called a "spark arrestor". It's a funny-shaped T with a screen in it. The screen is supposed to stop any flames or sparks that get coughed up that from (like from a backfire) before they can light the oil vapor in the crankcase. Which would seem to be an exceedingly unlikely possibility, but...

Like Aaahndy said, that's not supposed to be a part of the vacuum system. I guess it could possibly be, maybe. Perhaps if the PCV valve (the one in the hose at the oil filler) were removed? What happens if you squeeze that hose, the one to the filler, shut?

--DD

SirAndy · 05-10-2006, 09:28 PM

::this thread is worthless without pictures::

shoot a pic or two of your engine comp and post them here ...

Andy

rcrgrl · 05-10-2006, 09:59 PM

hope this helps.

on the first one, see where i circled? this hose has never been connected since i owned the car

the second is the one that i was saying drops the idle when i cover the hose

SirAndy · 05-10-2006, 11:03 PM

damm, that's a mess ...

good news is, you *do* have a vent-hose on your oil-filler neck. i can see it in pic2 ...

BUT, in order for all this troubleshooting to work, you *MUST* hook up the aircleaner and attach all the hoses to the correct places ...

some of these need the vaccuum pulled by the intake to work correctly ...

Andy

rcrgrl · 05-11-2006, 06:24 AM

yep, yep, its a mess! don't worry, i absolutely had the air cleaner on for testing - just took it off for the pictures cause i couldn't get a shot otherwise.

rcrgrl · 05-11-2006, 07:44 AM

Quote:

Originally posted by Dave at Pelican Parts
What happens if you squeeze that hose, the one to the filler, shut?

--DD

the idle drops nicely to about 1,000.

jsteele22 · 05-11-2006, 08:57 AM

Quote:

Originally posted by Dave at Pelican Parts
It is also called a "spark arrestor". It's a funny-shaped T with a screen in it. The screen is supposed to stop any flames or sparks that get coughed up that from (like from a backfire) before they can light the oil vapor in the crankcase. Which would seem to be an exceedingly unlikely possibility, but...

Like Aaahndy said, that's not supposed to be a part of the vacuum system. I guess it could possibly be, maybe. Perhaps if the PCV valve (the one in the hose at the oil filler) were removed? What happens if you squeeze that hose, the one to the filler, shut?

--DD

Ooh, ooh Mr. Kotter !

This is kinda what Dave said, but it sounds like the hoses from the cylinder heads are connected incorrectly. They route any gasses escaping from the heads back to the air intake so the gas gets burned, rather than causing pollution. But they should not be hooked up to vacuum. From your description of the symptoms, it sounds like they are. For testing, you can just disconnect those hoses, make sure your vacuum is tight, and once everything is running correctly, hook them to the air intake.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

The hose from the oil filler does go to the manifold. Sounds like there is no PCV valve in the fitting, or the valve is stuck open. You can try taking it out (the knurled part around it is a nut that holds it in, it comes out from below) and cleaning it with brake cleaner. Or just replace it.

Ray Greenwood over on the Shoptalk Forums talks about putting a plug in the middle of the hose with a hole through it, but I'm not sure that's the right solution. It'll bring the idle down, though!

--DD

SirAndy · 05-11-2006, 10:25 AM

Quote:

Originally posted by Dave at Pelican Parts
PCV valve

btw. my early 1.7L motor did *not* have a PCV valve in the filler neck.
just some metal gauze. the vent hose still went to the air-filter thought.

BUT, if you hooked it up to the manifold, the vaccuum would suck so much air right out of the filler neck that it would make a really loud and ugly noise, even at idle.

sooooo, if your oil-filler neck does not have a PCV valve, the vent hose should be connected to the top of the airfilter housing and *not* the manifold under the airbox.

Andy

rcrgrl · 05-11-2006, 07:49 PM

mine has a pcv valve and that was the problem. too it out, cleaned it, put it all back together nice and tight. idles beautifully. ... for today

thank you !!

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Oh, the small hose you were asking about in your first pic is the one that actuates the Decel Valve. It should hook up to a "stacked elbow" (which is an F-shaped piece where the two arms of the F are different sizes) that hooks up to the manifold. It's not a huge deal if you don't have it. I don't think that hose being loose causes a vacuum leak, but I'm not certain.

--DD

Stieve · 05-11-2006, 09:33 PM

Where is your hose going to from the oil filler? It should go to a 90 degree boot that connects to your intake air distributor,(pg 40 #4 in picture, in Haynes), mine did the same thing, due to a split in the boot, I bypassed it by connecting the hose directly. PM me if you want to call me.