328 auxillary air valve

Can you please take a shot looking straight thru the bores (towards a light background) at room temperature -- I'm curious to see if the shape of the opening is the same or different (I noted on my original TR AAV the moving edge was a simple curve; whereas, on a later, superceded version TR AAV, the moving edge was stepped).

 

No -- don't do that, but thanks for the offer. Do you recall noting any difference, or you did you not look inside each?

 

Thanks for the feedback.

 

Just for the record the UK price of these is 120 GBP from the above supplier. But you have to send them your unit as this is done by exchange.

 

I can't tell from the discussion, but did anyone ever get a good Bosch AAV part number?

From the Bosch part finder (http://www.boschautoparts.com/VehiclePartFinder/Pages/VehiclePartFinder.aspx) for a 83/84 QV it indicates part number 0 280 140 129

Can anyone confirm or provide what part number they purchased and used and probably as important where did you end up getting it from?

I found a place on the web http://www.importpartsgeek.com that has these parts listed in stock but at 3 different prices

140-104 $83.86
140-129 $42.72
140-229 $209.46

A bit of variation....

Any help is appreciated

Glenn Frenck

 

One thing to be careful of is these Bosch databases are often only for the euro version model (but I don't know specifically if an '83 euro and US version use the same AAV, or not) -- can't you read the ten-digit Bosch PN on your existing AAV?

Is your AAV mounted under the coolant tank (which I think is the ...129 type body) or on top of the engine (which I think is the ...104 type body)?

 

It's obvious that the WUR and the fuel distributor must be matched closely to the engine design, so using one for a different application isn't going to work very well.

But the AAV? It's just a device that lets more metered air in when its cold. It doesn't affect the control pressure, and it doesn't affect fuel delivery any differently than a small opening of the throttle would. And it doesn't do much of anything when the engine is warm. Sure, if the thing is way too large the cold idle will be too fast, and if it's way too small it will be ineffective - but we're aiming at a fairly large target here. So how important is it that one use the precise exact $700 Ferrari part?

 

Took a bit to find the AAV, it' wasn't under the expansion tank (??) but up front just off the plenum near the cold air valve. A bit of finesse with a mirror showed the part number was
0 280 140 129
picture below

Reply to Dan, sorry about the price and timing, didn't have my current problem so wasn't searching (the web or physically) for the part.

As for the symptom, start the car and it won't hold low idle and stalls out. If I hold the accelerator at around 1200 rpm no issues. Even after the warm up light goes out, if I take my foot off of the accelerator it drops and stalls.

I've been wondering if the recent cat replacement (for failed emissions), which apparently has the nice side effect of the coolant reading about 20 degrees cooler on the gauge hasn't been the trigger for this and the AAV isn't opening and closing properly anymore (part age/worn etc..)

Thoughts??

Regards

Glenn
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Why do you think that is a nice side effect? I'd want my gauge to be accurate, not falsely comforting. The nice side effect would be a guage that reads correctly. I'd make sure your gauge reads correctly. Maybe it was wrong before, maybe it is wrong now, but a 20* swing without touching the cooling system worries me.

 

Totally agree, this is a very non-critical part. There seem to be two body types, the large one with 4 screws in the corners used on USA cars (which seems to be openable) and smaller which is rounder in shape on Euro cars. The hoses are larger on the US ones. Other than that, cant see any need for the exact spec unless anyone has any other views. Its redundant anyway after 2-3 mins after starting, as long as it closes fully.

 

It is a pretty crude device and doesn't send feedback to any other part of the FI system as you mention. I've had a Porsche and a bunch of water cooled VWs with AAVs and they all work the same and look the same except for minor mounting differences. They might have different opening temps and might have different bore sizes. But engines' operating temps are all pretty similar so that's gotta be similar enough. And like you say the bore size will probably be adequate. If it's off a little the idle will be a bit higher or lower, but I'd give it a shot. I even have a 944 AAV in a drawer that I'm saving in case the 308 one goes out. I'm certainly going to try that one first. Heck, I might try it out for fun one day.

 

Had the radiator re-cored(sp?) 2 years ago, prior to that, gauge temp would go all the way to 225 without much trouble. After the rad job it's been steady at 195. After the cats being replaced, gauge temp shows around 170. Just an observation on my part and included to gain feedback from the community, as it was coincidentally noted with the first occurrence of the low (no) idle issue.

Glenn

 

I wouldn't bet the farm on this without doing more research , but the F models (like yours) using K-Jet without Lambda tend to have the smaller body style AAV that mounts on top of the engine:
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Whereas, the F models using K-Jet with Lambda tend to have the larger, rectangular body style AAV (like in post #52) mounted under the coolant tank.

If you remove the AAV, you can easily do the "refrigerator = open and oven = closed" visual look-thru test to see if you have a gross problem.

One thing for sure is that your cold start air valve must be disabled somehow or it is not working either. You might try a search on "cold start air valve" and read some of those threads to get more familiar with that system so that you can see if yours has been modified. It is interesting that your yellow cold-running warning light in the dash is working (as most people who want to disable this system just unplug the coolant tank thermoswitch and connect the two wires together always forcing the "warm-running" condition and that always keeps the yellow warning light "off"), so maybe there's some electrical or vacuum line modifications at the electrovalve running the cold start air valve.

 

[/QUOTE]
One thing for sure is that your cold start air valve must be disabled somehow or it is not working either. You might try a search on "cold start air valve" and read some of those threads to get more familiar with that system so that you can see if yours has been modified. It is interesting that your yellow cold-running warning light in the dash is working (as most people who want to disable this system just unplug the coolant tank thermoswitch and connect the two wires together always forcing the "warm-running" condition and that always keeps the yellow warning light "off"), so maybe there's some electrical or vacuum line modifications at the electrovalve running the cold start air valve.[/QUOTE]

6 months ago the rubber tube came off the top of the cold air valve and it would only idle at 3K until I found that tube, put it back on and zip tied it. You can just get a glimpse of that in my original picture on the right side.

Idle went back to normal after that (till now)

I've gone through all the service history of the car and there's no mention of the AAV valve being replaced and a careful inspection underneath the expansion tank doesn't show any mounting fixture or left over holes. I also went back to the mirror trick and confirmed the part number off of the back of the AAV, don't know what to say on why it's a 140-129 and not a 140-104 as you indicate it should be.

I've taken a few more pictures and will upload with this. picture IMAG0080 shows where it's hiding between the two hose clamps in the right quadrant of the picture. Picture IMAG0078 shows that corner of the right top of the engine with the cold air valve on the right and the AAV just behind it to the left.

Curious or what....

Glenn
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No, I believe 0280140129 is the correct AAV for your model. I just used a picture of 0280140104 because it was handy. Both are the smaller body style AAV that mounts on top of the engine.

 

If you always (cold or warm) have vacuum present on that small vacuum line going to the cold start air valve, something must be modified. The way the system is supposed to work is:

When cold = the coolant tank thermoswitch is open = this leaves the electrovalve unenergized = no vacuum reaches the cold start air valve = the cold start air valve is open = extra air enters the engine = the idle speed is quite high (like 3000 RPM).

When warm = the coolant tank thermoswitch is closed = this energizes the electrovalve = vacuum reaches the cold start air valve = cold start air valve is held closed = no extra air enters the engine = the idle speed is 1000 RPM.

Do you have an electrovalve present and the associated network of small vacuum lines (going from the intake plenum-to-the electrovalve-to-the cold start air valve), or is the small vacuum line connected directly from the intake plenum to the cold start air valve (i.e., vacuum always present on the small line to the cold start air valve)?

 

Traced the tubing and it goes from the cold air valve to the first fitting (on the right side straight down the "fin" from the word quatrovalvole machined on top of the plenum) in the plenum where it tees in from the bottom. The same fitting has that u shaped tube that goes towards the rear of the car into that other device (which is a <fill in the blank here>??) reference the top picture of my last post.

The F-car dealership that I take this to hasn't said anything about apparent "re-work" so again at a loss for what I'm seeing in the engine bay.

 

Yes, that modification (a direct vacuum line without electrovalve) would always put vacuum on the cold start air valve and always keep it closed (yet allow your yellow dash warning light to work normally).

That "other device" is called the "Vacuum Limiting Valve" (or VLV). It prevents the system from going lean under extreme engine deceleration with a fully closed throttle (by always ensuring that some amount of air is allowed to enter the engine during that condition).

Because they probably do the same modification It's very common to disable this cold start air valve system as it is a little crazy. If cat equipped, I'd prefer to see a modification that keeps the system working, but lowers the cold RPM to a more reasonable value, but I've said that before in those other "cold start air valve" threads...

 

Steve

Got the ignition tester today that your recommended and checked the engine. Have spark to all 8 cylinders. Thanks for this tip, for $7 it's a gem.
The engine was running a little rough and then died again. Started some more investigation and after some trial and error decided to take the tube off of the top of the cold air valve thinking back to our discussion. After I did that, it started up and ran smoothly at 1k rpm without issue. I took the car out for a spin, multiple stop and go's in the neighborhood and it idled without hesitation. Put the car back in the garage, popped the deck lid and started to slide the tube back on and immediately the engine started to stutter and die. Immediately stopped and took it back off and went back to a clean idle.

Talked about confused....

Not sure leaving it disconnected is the right thing to do, any thoughts?