Air hose below Coolant Resevior? STRANGE - NO START

Well I'm not a QV expert but it looks to me like it's Part #30 in this diagram which is called out as "additional air valve". Not being sure what exactly that does I'd guess it's either bad or the hose is clogged.

http://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/308-group/308qvus/fuel-injection-system-fuel-distributors-lines.html

 

Looks like the hose that hooks up to the air valve. Part # 30. Not sure what the function of the air valve is.

FUEL INJECTION SYSTEM ? FUEL DISTRIBUTORS, LINES - Ricambi America, Inc.

 

Pretty sure it connects the mergatroid to the skenecktakadoink...

 

FYI, it looks like you are missing one of the plugs off the sample port pipe there too.

 

Ha, I must have beat you by mere seconds. Funny we both posted links to Ricambi too.

 

Got to give the sponsors a plug whenever we have the chance.

 

That is the auxiliary air valve, part of the cold start warm up system. I think the hose runs to under the cold start injector on the plenum.


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The function of the aux air valve is to let additional metered air into the intake, and is only "open" (allowing air to pass) when the car is cold. With the hose disconnected, when the valve is open (car is cold), unmetered air is entering the system. If the car runs with the hose disconnected, but not when it is connected I'm guessing the mixture and/or idle and/or other things are all set to compensate for the unmetered air -- meaning of course, it's highly unlikely the car will run well when cold if the hose is connected again. Again, just a guess...

 

That's a very happy important hoe, I had mine came loose and it prevented me from starting my QV, it's like have a majore vacuum leak if that hose get disconnected.

 

That's right on from my understanding. The AAV, auxiliary air valve, on the underside of the coolant tank is a thermostatically controlled valve - it's about half open when the coolant is cold, then as coolant heats up the valve gradually closes. The purpose is to allow additional air around the throttle when the engine is cold to support a higher idle speed - the cold start injector adds extra fuel to coincide with the extra air.

As the coolant heats up, the AAV closes, and your idle speed drops to normal warm idle.

So, basically - kbento's idle speed and throttle adjustments must be really, really way out of wack; or the hose from the post-fuel distributor to AAV is plugged; or the AAV is broken, stuck closed, etc. If his car was set up correctly, then even if the hose or AAV was plugged or fully closed when the engine was warm it should make no difference to his idle or engine operations, since no air should be going through at that point anyway. (when the engine is warm)

 

Check out this You Tube Video. Its show checking that valve. https://youtu.be/O9G7CVGnZdE

 

I believe the description above is mostly correct. The AAV is controlled by an electronic bimetallic element whose signal determines the opening and closing. There is a separate thermostatically controlled switch on the tank.

 

Helpful thread ( post #5);

308 warm idle issue, WUR at fault?
http://www.ferrarichat.com/forum/showthread.php?t=337106


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I'm going to guess that the last person who "tuned" the car didn't know that hose was disconnected and did things to compensate for it. Yes, having that hose off lets unmetered air into the engine so it will either run super lean or something would have to be done to richen the mixture to get it to stay running at idle. As someone said, a massive vacuum leak when cold. I'd suggest getting the Bosh Jetronic book and going through the setup from the start. I'll bet the idle adjust and CO adjust for the car is way out of spec to make up for that hose being disconnected. Does your area have smog testing?

 

Does you car still have the super fast idle circuit enabled when cold? Does it idle at 2000-ish rpm for the first minute or so? If so, this might help mask that hose being off when cold. That other valve could be allowing enough metered air in that there's enough fuel to stay running when cold.

Then the engine chokes on too much fuel when the hose is connected? Hmmm, I haven't tried any of that either accidentally or on purpose.

 

Sorry third post. I feel like Big Tex.

That would be TWO major vacuum leaks when cold. The AAV would be letting in unmetered air and the hose that is off would also be letting in unmetered air. I don't think you could compensate the system enough to make the car idle like that at all. There's got to be at least one more piece to this puzzle. AAV is always closed or hose is plugged or part of both. Or something.

I just don't think you could screw with the system enough to make anything work with that hose disconnected and everything else as it should be.

 

The "screw" that you are missing (that has been replaced by the rubber plug) is just a cover screw (not an adjustment screw) -- functionally, having the rubber plug there is fine (and some model/years do use a rubber plug there IIRC). However, if the mixture adjustment screw (which is further down the hole the rubber plug is blocking) was adjusted with that hose on the AAV disconnected = when you reconnect the hose to the AAV, the system A/F ratio will be way different. Additionally, with that hose to the AAV disconnected, a large amount of air would be leaking into the free hose end of the hose into the plenum (thru the airflow metering device downstream of the airflow metering plate) = a very good chance that the throttle plate and air bypass adjustments are wacky too (if with that hose disconnected the idle is OKish). This is a downside of CIS -- when something goes wrong, a bunch of mis-adjustments of other items can sort of compensate for it. So if the problem ever get properly fixed, all those mis-adjustments need to be readjusted.

 

Its both. The bimetallic strip which moves the flap does have a heater but also the valve can be fully closed by heat from the tank. If the electrical plug is disconnected it does still function but closes more slowly so there is a period of excessive idle speed during warm up.

I forgot to plug it back in once and thats what happened

 

Thanks!


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IMO, your best reference would be the Mondial8/QV WSM 281/83 Chapter D. If your '85 is a US version, it's K-Jet with Lambda, but the basic set-up and idle tweak-up are done with the O2 sensor unplugged, and that essentially changes it into a K-Jet without Lambda as covered in 281/83. The basic adjustments starting from scratch IIRC are:

1. throttle plate cracked open a little from rest (something like ~1/16th of a turn).

2. Air bypass screw open maybe 1/2 turn (this conflicts a little with 281/83, but is, I believe, something that they changed to).

3. The mixture screw set to have fuel just come out of the fuel distributor ports (line to injector disconnected) with the fuel pump running and the conditions specified in 281/83 Chapter D (which I can't recall ).

4. If it's a US K-Jet with Lambda, confirm that the Frequency Valve is buzzing (by touch), when the fuel pump is running before doing anything else.

Good Hunting! (If you search on something like "K-Jet with Lambda" or maybe "K-Jet with Lambda air bypass" you should get prior threads -- maybe too many .)