Aux air valve - check, (oh, no!) replace?

[MrT]

Well, I looked at my '86 Spider tonight. It runs OK the first 10 sec after starting, but then tries to die (uaually succeeds). Blipping throttle, as opposed to holding it open, made/makes it stay in the game.

After finding mention of Aux Air Valve woes giving start then die symptoms in the white spider manual, I disconnected it. No change in starting behavior. Then I bypassed it for definitely open air bypass pkg. Found Spider tried to run faster with bypass, but soon (4 sec rather than 10 sec) died again (not enough fuel?). Still consistent with fuel starvation. Blipping throttle again helped.

Tried to test AAV on bench with 12 V from battery and then 12 V from trickle charger. AAV takes approx. 1/4 Amp either polarity but does nothing. Can see through air passage for AAV, no click when running 12V to switch.

When it gets warm, the engine will idle ar reasonable 1000 RPM ranges. All help greatly appreciated.

And is $284 (IAP) a price anyone else does not find outrageous for an auxiliary air valve? It seems big to me. I'd like to know what about anyone with

Michael

[John M]

Hey Michael:

I am still following your saga. Here is what the manual says on checking the AAD:

1. Auxilliary air device opening check:
a. Check that the engine is cold then start it and pinch the air device output pipe several times. (pinch the long air hose coming away from AAD to the intake plenum)
b. Check that the number of engine revs continues to decrease, to a lesser degree as time passes (with an environmental temp of 68 deg F) no further rev number decrease is recorded after approximatly 3 minutes.

2. Air device closing check:
Wih the engine at steady thermic rate, choke the air device output pipe (hose between AAD and intake plenum) and verify that the engine rev number does not decrease.

I think you got some excellent suggestions to check from the air and water temp sensors, bad injector(s), idle incorrectly adjusted, incorrect throttle rest position. One thing I will suggest is to use that new rubber air hose and make sure all of those clamps across the hoses from the AFM to the Plenum are tight. I know you noted that you already done this, but double and triple check. Check every vaccuum hose. At this point I would say replace all the little ones. They are dirt cheap and take so little time to do. And double check the runners between the plenum and intake....especially on number 1 and tighten those clamps on the plenum and intake for the runners as well.

One final suggestion is to measure the O2 sensor voltage. Might give you a diagnostic heads up if you can keep the car running. This just might all boil down to a faulty injector. In any case once you track it down....you will have done so much preventative maintenance that she will run like new....well at least we hope she will.

Best Regards,
John M

[papajam]

With all the sensors within specs, I'm leaning towards a vacuum leak and/or throttle plate stop screw out of adjustment. Have you tested for vacuum leaks using the carb cleaner method? With the engine running, spray carb cleaner around all the hoses and joints of the intake system. If (when) the engine speed increases or the engine starts running smoother, you've found a leak.
I'd check the AAV as outlined by John M but I don't think that's the problem.
Did the symptoms show up gradually or all of a sudden? Before or after any work was done?

[MrT]

We're bringing this car back out of the sickbed after it slowly wandered away from the healthy category while in the hands of the P.O. Car sat up awaiting attention for many months before P.O. gave up on being able to tend problems. Replaced all plenum to intake hoses when plenum was off. I found brake cleaner (which I have in hand) to be a flammable hydrocarbon which serves as leak detector just as carb cleaner does. The car speeds up with a shot in the main intake, and it helped me detect loose hoses elsewhere. We sprayed it all over the intake plenum hoses and got no sign of leak. It runs _so_ nicely for 5-10 seconds after starting. I may have to get an oscilloscope and look at injector pulse from ECU. After getting the clutch pivot pin replaced today (if possible with all else clamoring for attention) we'll go fill the tank and put some injector cleaner in it. I use Techron on the strength of recommendations from Alfa sources a few years ago.

The car works better (cold) when the fuel rail pressure is raised by removing the manifold reference to the fuel pressure regulator. The Aux Air Valve never fully closes. You can _see_ through it when it is disconnected (little pie-wedge opening with area of about 1/3 sq. em.). There is no change in engine behavior with AAV connector on/off. No sound or change in appearance when 12 V applied to terminals (34 ohm or so resistance). Seems an ill omen to me. Hose is presently too stiff to do manual procedure (clamp hose and look for slowdown). Engine does not run stably enough cold, either. Will replace all small hoses too. Will look for all connectors and clean them. May eventually pull all injectors and back-flush them. Ugly.

Already checked the water temp sensor, but don't know where air temp sensor is. In AFM?

Really, thanks for the suggestions and help. I will follow all, even if I don't understand how they could help. When you've exhausted the likely candidates.... There are so many reasons for being short of fuel here, and everything looks so much like fuel starvation. And primarily when cold.

Where does one get an idle adjust gasket? There seems to be _none_ in this unit so I tightened the brass fitting down snugly so it won't be sucking in unmetered air and it idles at 1000 rpm warm.

Michael

[MrT]

Subject demonstrates symptoms of brain fade.

I asked for aux air dev characteristics because I was confused about the AAD being open when I looked into it. Duh. It _should_ be open. Then it should close slowly as things warm up and time passes. But the AAD can't reasonably be a problem in the first 10 seconds unless it closes. And it shouldn't be able to do that with its socket disconnected. I get dying symptoms the same whether the AAD is connected or disconnected, so the AAD can't reasonably be at fault. Well, if I save someone else the time it took me to recognize this....

Michael

5 March 2004 addition: "the AAD can't be a problem" is a bit optimistic. The AAD _could_ be faulty and open too much. I suspect this is part of the problem, but the page that DaveC pointed me to in the Spider forum, Burnt#1Valve thread, post on or about 02-27-2004, mentions cleanup and adjustment of the AAD. Much better than $300 for speculative replacement.... Plan to replace embrittled hose on AAD so I can do the on-car test outlined above. I have found a cracked hose on the oil separater, a small 4'ish mm hose I didn't notice. It apparently routes oil back to the dipstick and was rubbing on the fender and leaks on bottom where it can't be seen or easily noticed. I found the leak by blowing back through the separator cannister and tracking down the rush of blow-by air.

Actually, it was George (#2 son, age 15) who traced the leak while I was serving as airbag....

Michael

[papajam]

The AAD should be open when the engine is cold to allow extra air to bypass the closed throttle plate. As the engine warms up, the AAD will start to close. The device should be fully closed with a hot engine. The electrical signal for the AAD comes from the ECU which gets the engine temp signal from the coolant temp sensor.
The AAD is not spring loaded and requires an electrical signal in order to open or close.

[Greg Gordon]

Hi Michael,
An AAD (also called AAV) stuck open in an otherwise intact system will simply cause a high and sometimes irregular idle. For the record I sell a manual AAV with a control cable on my website so I know how they behave in different positions. I also have instructions on fixing and testing the stock AAV so you don't have to buy a new one. The electrical connection on the AAV simply provides current to it so it heats up and closes faster, it's not your problem
However I don't think this problem is an AAD issue. More likely a vacuum leak.
Greg Gordon,
http://www.oldebottles.com scroll down to the Italian car link

[MrT]

Greg,

Thanks worlds for the oldebottles page. Someone posted a link to it several weeks ago, and it was invaluable to me in getting this thing straightened out. Unfortunately, I scattered some traces of my confusion in several places on alfabb. This thread is one. I posted my solution and path to it in a Burnt #1 plug summary. I have also scattered a few thank-you's to you and your page. I ultimately had to work up enough confidence in the rest of the car's hardware to let me dare look inside the AFM. It had been opened before, by the look of the RTV sealant, and I did the road test with multimeter hooked up to the O2 meter to guarantee myself that the car ran lean all the time. Then I richened it up and it runs well now. Just have to get a few more little things settled like speedo and defroster fan to satisfy legality and safety (in some order). Looking forward to teaching my 15+ yr old son George to drive in the car.

Michael