Aux Air Regulator Failure Modes Options

[customstarr]

I think that I'm having a prob with my AAR. Idle fluctuates up and down (1000+ RPMs down to near stall) during a cold start - it continues the up/down cycle for a few minutes then it's fine.

This morning during a cold start, I pulled & plugged the hose from the AAR to the Intake Boot (plugged the intake also) and the idle stabilized - granted the idle was low, but it did stop the up/down fluctuation.

From Anders site, I was under the impression that the regulator would either stick open or closed, causing a high or low idle respectively. Mine seems as if it won't stay open consistantly during a cold start - it's like it's opening and closing & causing the idle fluctuation.

Has anybody experienced this same condition?

[jim_hoyland]

Take it out and do a simple bench test. I put mine into the fridge for a 1/2 hour. Pull it out and see how far the hole is open. Mine goes to 30-50% open. Then I hook the AAR to the battery and see how long it takes to close off the hole. Mine take from 1 1/2 min to 2 min. If it just closes with power applied it works.

Your description sounds more like a vacuum leak. Been there too; I ended up installing a VDO vac gauge in the engine compartment. It gets T'd into one of the lines going to the plenum. Mine averages 10-12 lb at idle. Any leaks and it drops alot.

Good luck.

[customstarr]

Take it out and do a simple bench test. I put mine into the fridge for a 1/2 hour. Pull it out and see how far the hole is open. Mine goes to 30-50% open. Then I hook the AAR to the battery and see how long it takes to close off the hole. Mine take from 1 1/2 min to 2 min. If it just closes with power applied it works.

Your description sounds more like a vacuum leak. Been there too; I ended up installing a VDO vac gauge in the engine compartment. It gets T'd into one of the lines going to the plenum. Mine averages 10-12 lb at idle. Any leaks and it drops alot.

Good luck.

Thanks. I don't have any vac leaks - checked that a long time ago. Like I stated, when I remove & plug the AAR line from the intake, the idle stabilizes.

[highways]

I am experiencing the same fluctuating problem. Idle ocillates betwee 1,200 Rpm and like 600. Re-did all the vacuum lines at this point.. I think there's little chance of a significant leak right now. Other then that- I don't know where to begin. I did buy a complete D-jet setup so I can start swapping out parts and hopefully find it.

[Dave_Darling]

Failure modes for the AAR:

1: Freezes open, so you get normal idle when cold and rather high idle when warm.
2: Sticks partway open, so you get low idle when cold and high idle when warm.
3: The heater doesn't work (broken filament or wire, or unplugged) so you get normal idle when cold, high idle when partly-warm, and after a looong while normal idle when good and warm.

They usually don't stick closed--and the partway open thing is also pretty rare. #1 and #3 are the typical failure modes.

Sounds like you have a lean mixture, causing an "idle hunt". If your car is a late 71, try tweaking the knob on the ECU a few clicks clockwise. If not, try unplugging the intake air temp sensor on the manifold to see if that makes a difference. (That one should richen the mixture a little across the range.)

--DD