What is this valve ?

[sblake01]

If I were you, I wouldn't bypass the heat block. The reason being that the housing under the AAR is the heater housing for the thermal vacuum valve. The termal vacuum valve allows the egr system to work while the engine is at operating temp. It really doesn't have anything to do with the operation of the AAR. Simplest (and best) thing to do right now is remove the bad AAR and connect the hoses together that run through it. That way, all you lose is the fast idle during warm up and when you find a new AAR, which would be my suggestion, all you'll have to do is put it on and plug it back in.

[preith]

If I were you, I wouldn't bypass the heat block. The reason being that the housing under the AAR is the heater housing for the thermal vacuum valve. The termal vacuum valve allows the egr system to work while the engine is at operating temp. It really doesn't have anything to do with the operation of the AAR. Simplest (and best) thing to do right now is remove the bad AAR and connect the hoses together that run through it. That way, all you lose is the fast idle during warm up and when you find a new AAR, which would be my suggestion, all you'll have to do is put it on and plug it back in.

I have to disagree. Unless my memory eludes me, which is entirely possible, on my '77 the only thing that was under the AAR valve was a coolant block, no valve, etc (his picture seems to confirm this), perhaps this was a later model addition?

Originally I removed the coolant block only and left the AAR. The AAR would not shut and the engine "high idled" indefinitely in colder weather (30's), so I concluded the block did serve the AAR.

Regardless, you could remove the EGR as well, the easiest way of course using a 75-76 intake manifold.

Edited January 19, 2010 by preith

[kjphilippona]

I ran a hose from the TB to the T, the car started right up no rich smoke. The valve must have been broken because the fast idle never worked, it works no, i guess the engine idled at around 2600 rpm, a little fast for a cold engine in my opinion so i shut her down.

[sblake01]

I have to disagree. Unless my memory eludes me, which is entirely possible, on my '77 the only thing that was under the AAR valve was a coolant block, no valve, etc (his picture seems to confirm this), perhaps this was a later model addition?

That's entirely possible as mine were a 78(280Z) and a 79(810) and both were set up as I described. Also they were both California cars if that makes difference.

[Zed Head]

I had the same problem with the Air Regulator (what Nissan calls it) on my 76. I pulled the guts out just like you did while trying to get my engine running correctly. Then broke one of the bolts n the manifold when removing it. I spent a lot of time at the oven and freezer figuring out that it didn't work right anyway.

Not to be contrary, but actually I think that if you are going to remove it, you need to block the air hoses off, not connect them. Otherwise the high idle never goes away. The regulator is open when cold, allowing extra air past the throttle body to give the high idle. It completely closes when warm, it actually has a small 12v heater and bimetallic strip inside, to warm it up and close it before the motor warms up. It's described on page EF-17 in the 77 manual.

From an engineering perspective, I think it's true purpose is to get extra air in to burn off the extra fuel from the cold start valve, the start enrichment and the after start enrichment from the ECU. It does the same thing as holding the throttle open a little bit.

It looks like primitive technology but they still used them in to the 90s.

[sblake01]

AAR=auxiliary air regulator, AAV=auxiliary air valve, AAR valve I guess is some kind of combinitation of the terms. All would actually be correct. Bosch calls it an AAV. They invented it. All that being said, we know what's being discussed here. I doesn't do the same thing as holding the throttle open a little bit. It has nothing to do with burning off the extra fuel from the cold start valve as that is basically a one shot deal. It adds extra air to go with the extra fuel provided by the temperature sensor during the warm up period. The amount that the flap is open determines the speed, slowing as it electronically closes as the coil in it heats up. You are right about plugging the hoses though. The reason I didn't think of that is because I never removed mine, nor would I have. Primitive, yes. But the more of the system you remove, the more you have to concern yourself with compensating for the fact that those components are no longer part of the system. My opinion is still buy an new air regulator (or whatver you choose to call it).

Edited January 20, 2010 by sblake01

[kjphilippona]

Do you know if one for a '80-'83 280zx will work on my '77. One for my '77 is hard to find but one for the 280zx are avaliable.

Edited January 22, 2010 by kjphilippona

[sblake01]

You can use one for an early 80s BMW. Had one on my 78 280Z for about 10 years and one on my 79 810 for 5 years. It's a direct replacement.