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Discussion Starter · #1 ·
I'm suspecting a bad auxiliary air valve on my 1985 GTV-6, which has a hard time starting/instant stall after start/poor cold idling.

I have read the other AAV-related posts here, as well as this article:
L-jetronic Fuel Injection Technical Troubleshooting Article
Both have been great in helping me understand the AAV a bit, but haven't seen anything that quite matches what I'm seeing with mine.

Here's what I've done:
- Removed the AAV. It was virtually completely closed, which I assume is the cause of my cold start problems.
- Cleaned the AAV with carb cleaner over the course of a couple days, and never saw the unit open or close, even when thrown into the freezer or oven
- Decided to completely remove the adjustment screw
- Five minutes in the freezer, or in the oven at 150 degrees still seemed to have no effect (still virtually closed)
- Found that I could force the valve open manually with a screwdriver, but it just springs back closed. It doesn't seem stuck (anymore). It seems to move pretty freely when opened manually with the screwdriver. It just won't stay open. It bounces back closed instantly.
- Screwed the adjustment screw back on. Can't tell any difference in behaviour with the screw on or off.

So my questions are:
1) Is my AAV broken? With it in the freezer for 5 minutes, it still won't open up on it's own.
2) What is the purpose of the adjustment screw? What is it supposed to do?
 

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But Mad North-Northwest
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You need to loosen the adjustment nut, hold the flap open with a screwdriver, and then tighten the nut. If you do this and it doesn't stay mostly open, you need a new one. If it stays mostly open but then doesn't mostly close when you heat it up, you need a new one.
 

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Discussion Starter · #3 ·
Thanks Gubi. I was afraid of that. That was something I already tried.

Loosen screw. Manually hold flap open with screwdriver. Tighten screw. Remove screwdriver. Flap snaps shut.

I guess I've taken this repair as far as I can go then. Anyone buy one recently? What can I expect to pay for one?
 

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But Mad North-Northwest
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You are in luck: Rock Auto appears to have them on sale right now for $40.

For some reason it doesn't show up under the GTV6, but the Milano 2.5L one should work fine (I can't imagine why not). Pull up an '88 Milano and look under "Fuel/Air"...it's listed as an Idle Air Controller for some reason. Part is AC350.
 

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If anyone has success with a $40 AAV please let us know. The usual price is triple digits...!

I have >1/2 dozen (used) AAV's for Spiders & GTV6's. One works well, a couple barely work and the rest are dead. I suspect the lazy ones are nearly dead. So I installed a manual AAV on our GTV6. Works great - full open gives ~1800 rpm when cold. Of course one has to remember to manually close it.
 

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But Mad North-Northwest
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That $40 part at Rock Auto is a direct Bosch replacement, at least for the 2.5L V6 (it says "Standard Motor Products" but the one they shipped me is Bosch...this very often is the case for parts they sell under the Standard brand). I bought the same part # a couple of years ago for my Milano, but it was $90 at the time.

Normal price is still $90 but they're running a closeout special at the moment. Price is so good I ordered one as a backup.
 

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Discussion Starter · #7 ·
Thanks for the heads-up, Gubi. That looks promising.

That Bosch unit they sent you...would you happen to have it handy? The faulty unit on mine has a Bosch part number of 0280140124. Does it match?

The picture they have for their part #AC350 certainly looks like the Bosch unit I pulled out of my car.
 

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But Mad North-Northwest
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It's on the Milano so I don't have any easy way to check. Works perfectly, though.

When the new one comes this week I can let you know.
 

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Kewelj,

One of your biggest mistakes is not throwing out the carb cleaner. It's just junk and leaves a residue that is abhorant especially to electrical components. Use either non-clorinated brake cleaner and/or electronic cleaner in your case and NOT electrical cleaner as there is a difference. Mine was sticking but no longer any issues after proper treatment when I got this GTV6.
 

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Discussion Starter · #10 ·
Thanks for the suggestion, Brookstroutr. I may give that a try.

Having said that, though, I can manually move the flap pretty easily manually with a screwdriver. It seems to move pretty freely. The problem doesn't seem to be that it's sticking (anymore). The problem is just that I can't keep the flap open. As soon as I remove the screwdriver, it snaps shut. And neither freezer nor oven has any effect.

Doesn't that suggest that the AAV is already pretty clean (though likely faulty)?
 

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Discussion Starter · #11 ·
I checked with Rock Auto. It seems that their part #AC350 does indeed cross reference with Bosch part #0280140124 (which was stamped of the faulty unit that came out of my car).

I'm going for it.
 

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kewelj,

Go for it! I get sucked uo into repairing thngs from stubborness when it's a whole better to buy new and replace the ooooolllddd part.
 

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But Mad North-Northwest
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Well, it came in the mail today. It's a Bosch 0280140188, which is a slightly different number than kewelj found above. I have no idea what # the last AC350 they sent me or the original part on my Milano were. This may be a cross-reference replacement or something.

Anyway, it looks pretty much identical. I'd be amazed if it didn't work, but I've been wrong before.
 

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Gubi,

Could you perhaps check out how much the new one actually does open when cold (freezer) please?

I've had 2 second-hand AAVs and after cleaning and freezing, I found they both only opened about half way.

To get a usable idle when cold I resorted to putting a resistor in line with the heater in the AAV to slow the opening down. I got sick of keeping my foot on the accelerator when cold.

Thanks, Al.
 

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But Mad North-Northwest
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I threw it in the freezer at 0F (-18C) and as you stated it only opened about half way. I'd assume this is normal.

I've never had trouble with cold idle when the AAV was working properly. I'd check that your idle speed is set correctly for starters.
 

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Thanks Gubi.

I’ve had to adjust the idle speed high to keep it going when cold, but not so high that the L-Jet “hunts”. I keep 17 & 19mm spanners in the glove box.

Sealed up the intake leaks, replaced all of the rubber tubing etcetera...

In Australia we also have an emissions related “excess vacuum valve” that is supposed to reduce intake vacuum when the throttle is suddenly shut at high revs. It’s connected between the plenum and the air intake on the filter side of the throttle. Mine was gummed up and idle would randomly step up or down when warm, by about 500rpm. Took me ages to trace that as an issue.

My AFM had been fiddled with and was running way rich. Nice if you like cleaning fouled plugs every month.

After a couple of years of fiddling I’ve got the idle set at about 900-1000 rpm when warm. 22 ohm resistor in parallel with the AAV heater keeps it going when cold. Mind you it’s winter here at the moment with 2 deg. C mornings. Interesting to see how it goes when it warms up.

AL.
 

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But Mad North-Northwest
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Hunting idle on the L-jet is often a symptom of a tired oxygen sensor. If it was running rich for a while you might've coked yours up. Not saying that's definitely your problem but maybe something to consider. I'd also double check your throttle position sensor for kicks-and-giggles.
 

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Thanks for the suggestions.

My car is a pre-oxygen sensor car. And no vacuum to the distributor! Only car I’ve owned without that.

Throttle switch has been checked a few times, happy it’s ok.

And the switch on the AFM. The flap stuck once, that took a while to find.

All the temp sensors measure within spec. at a range of temperatures.

The L-jet has a function to cut fuel on over –run when it thinks it’s above idle with the throttle closed it cuts the injectors. Kicks in above about 1,500 rpm. Found that in a generic L-Jet document from Bosch. When you’ve got the idle set too high the revs slowly ramp up then drop suddenly as the injectors are closed – a saw tooth function. Embarrassing when stopped at the lights.

I haven’t cleaned the oil goop out of the intake, AAV & tubing since I leaned out the AFM.

Engine is getting pretty tired, needs rings, valve guides, gaskets &c... Not far off 300,000 km.

AL.
 

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OK, we're bantering here or whatever. Let me strongly suggest a quick piece of educational advice that I did when I first got this GTV6 ('04). I went to Greg Gorden's regarding this very issue and followed his instructions for IIRC cleaning and setiing up the AAV. Not a lick of problems since. Start up in all weathers is proper and continues to operate as designed after warm-up.

Oh and I might add, I rarely just get lucky....
 

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Cleaned the AAV regularly, found the adjustment screw does make a change, but not a lot.

Greg Gordon’s guide is very useful indeed, have been through that. I have an intake tube with shoe-goo on some doubtful looking places. I wonder if a previous owner had followed Greg’s advice on adjusting the AFM spring/wiper as the cover had been removed at some stage (roughly). Have been tempted to try Greg's method of replacing the AAV with a manual heater tap. I haven’t replaced the intake coupler rubbers, so they could be an issue too.
 
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