328 auxillary air valve

Tonight's saga

Wanted to drive tonight and fired up the car and the idle went straight to 2800rpm(?!?!). Put the rubber tube back on the top of the cold air valve and the idle dropped to 1000rpm. Warmed the car up and went for a drive. About 20 minutes into the drive and the stalling at intersections came back!!!!

Got it home and went through this again, disconnect the tube to the top of the cold air valve, idle jumps to 2800rpm. Put the tube back on and it runs rough and stalls.

Just do not know what to look at now....... Any hints or advice?

Bad cold air valve?
Bad Vacuum limit valve?
<fill in the blank>?

 

You should really start your own thread since this doesn't have much to do with a 328 AAV.

Sounds like your cold start air valve is now working as it should (no vacuum = open = high idle RPM and vacuum = closed = normal idle RPM). A Vacuum Limiting Valve problem can really only cause a high idle RPM situation or a stalling after hard engine deceleration problem (so not a likely suspect for a "rough and stalls" warm idle problem IMO).

It sounds like you (now) have a bimodal warm idle behavior (sometimes good/sometimes bad). As (relatively easy) preliminary preventative steps, have you cleaned/improved your DigiPlex ECU grounds and had a look inside the distributor caps to check for anything odd/bad (moisture/oil/broken pieces/etc.)?

 

Just my two cents.... If you have the older style ( electrical connector on top) you'll notice a small stud and nut on the body of the AAV... This is a small adjustment screw, if your valve is working somewhat, it may just need a little adjustment to ensure it's closed when warm.
The stud is spring loaded and you have to physically move the stud back and forth, then when its to your liking, tighten the nut.
As far as I can tell... This is to allow a very small amount of air in, the only reason I can think it might be needed is for real cold climates but you would have to re adjusted in the summer so I don't know...it may also have something to do with altitude and may be an altitude manual overide of some sort to allow just a bit more air as its warming up. If someone knows for sure what the purpose is please post.

 

Hmm mine is mounted on the upper part of the rear head and has rubber insulators so I don't think that's where it senses the heat from however, looking at the schematics, it is electrically actuated by the coolant temp vacum switch on the overflow, sends a vacum to a vacuum actuated switch that then sends a signal to a AAV...my guess is that the temp sensing is done by the coolant temp and not necessaraly by where its mounted.

 

I can't get the importpartsgeek to to work, what am I doing wrong? I may need one, thought I'd check availability.

Jeff

 

Ditto on not getting site to work. Not ditto on needing one (oops, may just have jinxed my car).

 

The site appears to be

http://www.partsgeek.com/

Though no aav there.

 

Right, so I'm confused where this info has come from.

 

Part # 0280140218
1983 Porsche 911 Auxilliary Air Valve
Bosch

Posting here for posterity only. Still a rare part. I may have found a similar part for $200, will keep everyone posted.

 

I just picked up a used 0 280 140 209 for $27 off of Ebay, the same unit PT 328 got new for $700.

Fingers crossed.

 

Damn you Jim. Where was that Ebay sale when I needed mine.

 

I went to Ebay and typed in 0 280 140 then scrolled through the options just to see what else was available. It's amazing how many lookalike parts there are. Most of them for Porsches. The parts that end in 200 and 222 look identical to the Ferrari part, but of course there's no way to know what's inside. I bought the 209 part based on your post, and your follow up that it worked! Thanks for that.

 

I am glad I could be of assistance even though my wallet is a little lighter.

 

Well, hell.

New part arrived. I put it in the freezer, it opened. I put it in the oven, it closed. Ok, it works.

Put on the new "used" AAV this afternoon. What a pain in the butt. It's NOT easily accessible, but I got it installed. I unscrewed the expansion tank to help get to it. Took the car out for a drive and the idle was back to normal. Until I got home. Then I was back up to 2k rpms after a 20 minute drive.

Glad it was only $27. Testing the old part now. The freezer made it open, haven't been able to try the oven yet.

I guess it's going to need a real mechanic.

Steve, I got your pictures, but need to get to real computer to post them.

 

Pictures. Hot = closed, cold = open. It never opened completely, but that was as open it got. Steve, the opening is round.

My results are the same as PT's.

I tested the old unit last night and it worked correctly. Well that was fun.
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Did you ever get it sorted?

Regards
Roy

 

Could be I got one for sale used. PM me if interested.

 

Yeah. New spark plug wires.

 

Old thread but... for the record testing the AAV by heating and cooling it is not the right way because it wont test the internal heating element. The right way is to apply 12 volts on the connector and it should gradually close.
If the heating element is open circuit or the contacts on the connector are corroded (been there) an intermittent fast idle will occur because there is not enough residual heat to keep it closed unless the internal element is working.

 

Thanks for the offer Robert, I need to get it tested before I make a decision on what needs to be done!
The car is going for a service in a few weeks I will get them to check it out.

Kind Regards
Roy

 

Lol.

 

Thanks Andy I will get Emblem to do as you described.

Regards
Roy