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Discussion Starter #1
Buon giorno, ragazze e ragazzi,

Nostro '82 Balocco SE has always had an "unstable" idle when cold. Only when cold. It cycles between 1,200 then down to 5-600, and up again and brings on idle-neutral-rollover rattles from the tranny and sometimes even quits.

Question: What fittings are involved with running the car when cold? What might not be working properly when cold?

So far myself and a dedicated Alfa mechanic have found no leaks, cracks, nothing adjusted wrong, ECU and O2 sensor working properly. I bought a new intake trunk, checked all the various odd fittings at or near the intake system, and found one with a kind of a spring loaded disc and aperture inside, like an air bypass fitting, which was full of gunk, so I got it all cleaned up and want to THINK that it helped, but not really solved the problem.. so what other fittings are there?

As stated - at warm idle, everything is tuned and behaves perfectly - to the point that I achieved a new personal best lap time this season.

Grazie,
- Art
 

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I could never get the Idle Air Controller to work well. I deleted it on my car and then used to use to rip a small piece of cardboard from my cigarette pack and slide between the throttle cam and the return stop to keep the Idle up while it warmed.. I'd finish my cigarette just as the GTV6 was getting up to operating temp (and stable idle), pull out the cardboard, shut the hood and off we went.

I quit smoking though, so I've got to come up with another solution. I'm planning make a manual, cable operated, idle air controller out of something like this: https://shop.advanceautoparts.com/web/SearchResults?storeId=10151&catalogId=10051&langId=-1&searchTerm=74627

The other alternative, I suppose, is to go to a standalone ECU and use a more modern electronic idle air controller.. or even a drive-by-wire throttle.. but that's definitely a more complicated solution.

I don't know if that helps much, aside from to say that I believe cold idle problems are fairly common in these cars.. I would not suggest taking up smoking just to have ready access to small pieces of cardboard to help your car run when cold though... even a standalone ECU conversion is cheaper in the long run ;)

Good luck,

-Dave

Sent from my SM-G930P using Tapatalk
 

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Click on the link in my signature (you first have to click 'show full signature') for a page of info about the L-jet system in our cars.

The AAV (Aux Air Valve - sounds like the gunk filled device you mentioned) is supposed to be open when cold to allow extra air in which the computer then adds the extra gas needed to increase the cold idle speed. As the engine warms up the AAV is supposed to close and return the idle speed to normal (as set by the Idle Air Adjuster). In my experience, all the AAV's are now old and barely working (if at all). The usually fail in the half-open range so they do no good for either cold or warm idle. I replace the AAV in our GTV6 with a manually controlled valve. You just have to remember that it is self-closing (you have to close it yourself...). The AAV in our Spider does work properly - cold idle is about 1400 rpm and it then returns to 900 rpm after a few minutes. But I don't know how long it will be before if fails, too.

Another thing to check is the TPS (Throttle Position Switch). The throttle stop screw on the throttle body is not meant to be adjusted. It is there to prevent the throttle from slamming shut. It is supposed to be set so that the throttle is just barely open and the idle speed is then properly adjusted with the Idle Air Adjuster. The TPS tells the computer the throttle is at idle position whereupon the computer follows it programmed idle map. If the TPS (or idle stop screw) is misadjusted the computer won't know the throttle is at idle and it'll try to constantly adjust the mixture based on info from the O2 sensor. But at idle that is not reliable so the idle speed will hunt.
 

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Discussion Starter #4
Thanks guys, that is all very useful stuff I can get to work on. Much appreciated.
Eric, I've looked at your L-jet info before, but that was several years ago, I'll go get a refresher.
And Dave, yeah, LOL - thanks I won't start smoking ....yet.! LOL
- Art
 

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Click on the link in my signature (you first have to click 'show full signature') for a page of info about the L-jet system in our cars.

The AAV (Aux Air Valve - sounds like the gunk filled device you mentioned) is supposed to be open when cold to allow extra air in which the computer then adds the extra gas needed to increase the cold idle speed. As the engine warms up the AAV is supposed to close and return the idle speed to normal (as set by the Idle Air Adjuster). In my experience, all the AAV's are now old and barely working (if at all). The usually fail in the half-open range so they do no good for either cold or warm idle. I replace the AAV in our GTV6 with a manually controlled valve. You just have to remember that it is self-closing (you have to close it yourself...). The AAV in our Spider does work properly - cold idle is about 1400 rpm and it then returns to 900 rpm after a few minutes. But I don't know how long it will be before if fails, too.

Another thing to check is the TPS (Throttle Position Switch). The throttle stop screw on the throttle body is not meant to be adjusted. It is there to prevent the throttle from slamming shut. It is supposed to be set so that the throttle is just barely open and the idle speed is then properly adjusted with the Idle Air Adjuster. The TPS tells the computer the throttle is at idle position whereupon the computer follows it programmed idle map. If the TPS (or idle stop screw) is misadjusted the computer won't know the throttle is at idle and it'll try to constantly adjust the mixture based on info from the O2 sensor. But at idle that is not reliable so the idle speed will hunt.
I agree that the AAV is a likely cause of a low idle, and once the un-heated oxygen sensor (OP's car is an '82) begins to warm up and generate a voltage, it can cause a loping idle when cold, but before the sensor is warmed up. This can also happen if the base mixture is way off (vacuum leak, etc), and the Lambda system is attempting to compensate as the engine controls go into "closed loop" mode. This can be proven by disconnecting the O2 sensor before the next cold start----the idle will likely stay low but will be steady. On '80s L-Jet and Motronic cars I always disconnect the O2 sensor before diagnosing a suspected air/fuel mixture issue.

However, I disagree about the TPS. First of all, the early GTV6 ('81-83) does not even have an idle contact switch on the throttle body sensor; there is only a full-load contact to signal the engine control unit to enter "open-loop" and ignore the O2 sensor feedback when the throttle is open wide. The later cars ('84-86) do indeed have an additional idle contact in the TPS, but this is only there to shut off the fuel injectors during periods of closed-throttle deceleration, which saves fuel; there is no separate "idle map". Later Motronic-equipped engines also use the idle contact to activate the idle control valve when the engine is at idle speed.
 

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My '82 had a really unstable idle at startup. It was the AAV. The bi-metallic strip that opens/closes the valve essentially wears out over time, so that it simply doesn't respond to temp variations anymore. Bypassing the AAV and dropping in a cheap, $15 cable-operated Ford heater valve is an easy solution (I think mine is from a mid-90s Ranger). I have it rigged with a lawnmower throttle cable at the moment, but am working on a cooler solution using a servo and a potentiometer.
 

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My '82 had a really unstable idle at startup. It was the AAV. The bi-metallic strip that opens/closes the valve essentially wears out over time, so that it simply doesn't respond to temp variations anymore. Bypassing the AAV and dropping in a cheap, $15 cable-operated Ford heater valve is an easy solution (I think mine is from a mid-90s Ranger). I have it rigged with a lawnmower throttle cable at the moment, but am working on a cooler solution using a servo and a potentiometer.
Does your '82 have the hand throttle lever on the left side of the dash? My '81 has one and it is very handy for both cold starts and setting ignition timing, diagnosing driveshaft vibrations, etc. I am curious if and when Alfa eliminated this.
 

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My '82 has the hand throttle. I tend to only use it when I'm idling at a long light and the engine is cold. It's sort of sticky and imprecise, so I find the manual AAV easier to control for cold engine management.
 

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Discussion Starter #11
OK, so maybe '82 was the last year.

I also use the manual AAV to increase the idle when the A/C is on & I'm stuck in traffic.
Oooo.... yes I do have the "Italian Cruise Control" lever on mine... of course, I can use that to hold the idle up and stable when cold... Grazie! First though, I will start it with the O2 sensor disconnected just to check how it behaves..
Ciao, - Art
 

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Before i'd do any of the above i would check the main air intake hose. Especially the accordion section. they are known for very small air leaks that will leave your idling go up and down.
 

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Are AAV's for 2.5 and 3.0 V6's still available anywhere? I remember buying one a year or so ago, but now I can't find any for sale.
 

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Discussion Starter #15
Are AAV's for 2.5 and 3.0 V6's still available anywhere? I remember buying one a year or so ago, but now I can't find any for sale.
I honestly haven't looked for one. I sometimes use an Alfa mechanic in the Berkshires, spoke with him l last year, he said they're NLA, but I'll surf around on Centerline, see what shows up.
Grazie,
- Art
 
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