Fast Idle system

Remove the aux air valve and stick it in the freezer. If if opens that is good, remove it and stick it in the oven, set at 150 or 200 and see if it closes...if it does, then all is good. I bet it is probably stuck closed though.

More, technical details here http://www.auto-solve.com/mech_inj.htm

Not sure of a source, but if you can find the Bosch part number off it, I would think that any Bosch parts house could order it for you...that is, I doubt it is a "Ferrari specific" part....

 

I've been down this road. I cleaned the aux. air valve with carb cleaner, lubed it with WD-40 and corrected the problem.

 

DaveHanda, I guess you're talking Fahrenheit?
If it Celcius, I'm afraid the valve will head south.

 

Of course! In North America, our ovens are calibrated in degrees Fahrenheit.

 

Did the aux valve correct the problem? I am guessing I have a similar problem as I was not getting the 2800 RPM warmup mode at all.......until today. Now I have it all the time. Sounds like the valve is stuck and just switched over to the other (stuck) position.

 

Don't forget 83' QVs have a shiny silver dome shaped valve with a vacuum line on top of it. It is located right beside the plenum on the pass. side of the car. It has been a while but I think it is called the cold start air valve or something along those lines. You may want to check that also. First see if vacuum is getting to it. If it is then you can manually put a vacuum to it and see if that raises the idle. Also remove the vacuum line and plug it and see what this does.

 

Carl if you have an 84 or 85QV then it is very easy to test. You will see a vacuum hose that runs underneath your coolant expansion tank to the lower chamber of your air flow sensor/fuel injection metering where the fuel distributor is. While the car is running at high idle simply grab this hose and pinch it so no air/vacuum can be pulled through it. If that drops your idle then you know the AAV is to blame.

 

Removing the vacuum line will cause a significant increase in engine speed. The vacuum line is sometimes knocked off when checking the oil. If you take off the vacuum line with the engine running you will see the linkage to the actual valve move. If you see no movement (with warmed up motor) you either have a problem with the vacuum source or the operation of the electrical portion of the sys., (electro valve, temp sensor, etc.). The vacuum line and the temp sw. were the two most common failures in that particular sys. And I know this is going to sound stupid but you won't believe how many times I've seen it happen even though the owner says he's sure thats not it, but please check. Two words "Floor mats" , causes more idle speed problems in Ferrari's than all others combined. Make sure they haven't migrated forward into the gas pedal.

 

Thanks guys. I did check the floor matts as they do tend to push forward, but not this time. Will follow up with the vac line test and such in the am. Thanks for the tips. Will advise.
Carl

 

Poked around this morning to get an idea of the layout of valves and vac hoses. Not started the car yet as the wife is still snoozing and at 2800 the house tends to shake a bit.

More detailed background for my problem......When I bought the car last winter, the idle speed was 2800 under all conditions. Not knowing any better, I adjusted the idle stop to the min position and was able to get it down to about 1200. Still a bit fast, but not leading to an overheat at any given stop sign. Lived that way for about 3 months until one day after a long highway drive, the car immidiately stalled at idle. Adjusted the stop to bring it to about 900 and was fine until yesterday when the reverse happened.

Given the quarterly flip flop, I am tending to think that a stuck (stickey) valve would be more likely than a vac hose. Cold start valve was easy to locate, but not sure about the referenced AAV. Are there two valves or are these the same unit? (83-308QV) Given the discription of symptoms early in the thread, that is my first guess.

 

After running this morning, the more accurate discription is that RPM's run at 1000 on startup, but increase to 2800 after car has passed 140 degerees temp. (Warm idle)

Did some looking on the Bosch web site and found a list of Bosch part numbers for the 83 308 FI system, which includes cold start valve, vac limiter, Thermo time switch, AAV and warm up regulator.

Still scratchin my head on this one.....

 

Carl do you have an 83'? I assume so. If so then the AAV is right next to the Cold Start Air Valve. It has an electrical plug that connects to it. It should be a black electrical plug. You can either remove the AAV and check it as Dave said or you can pinch one of the lines connected to it. If the idle drops then you found your culprit.
Did you remove the vacuum line from the CSAV? Did you apply vacuum to it with a hand vacuum pump? Try these then report back.

 

The AAV is different from the shiny dome shaped cold start air valve, not to be confused with the cold start injector.

 

I found the source of the problem. The Cold Start valve was not actuating (turning off) when the engine was warm. Traced back to the thermo-neumatic switch under the AAV which feeds vac to the CSV. For now I bypassed the switch and fed the manifold vac directly into the CSV, which provides the proper idle, and cold start does not seem to be a problem in the summer weather. Now to pull the switch and fix it properly.

Thanks to all for your on target support!
Carl

 

On 80 thru 83 308's the vacuum operated fast Idle valve was only for emission purposes. At a very high idle the motor ran cleaner at those speeds, clean enough to pass the cold start requirements for the Federal test. If that is the part of the sys that is not functioning correctly just give it vacuum all the time so that you have a correct idle and forget it.

 

I'm now working a similar issue with my 84 308. I've removed the AAV from under the espansion tank, dunked it in carb cleaner, and lubed it with WD-40. Using a screwdriver, I was able to move the moon/shutter within the valve very easily.

Then, I put the unit in my freezer. Once fully chilled, I pulled the unit out and looked through the valve - the moon/shutter had rotated 'wide open', even without the 12V applied. I connected the valve to the car, turned the ignition, and noticed no change, so on to the next test....

I set my oven to 200 degrees F, put the valve on a cookie sheet, and baked it for ten-fifteen minutes. Using an oven mitt, I checked the valve and the moon/shutter was fully closed (again, no power to the electrical connection). I then ran power to the unit from the car plug, no change at all - still closed. Then I let the unit cool to room temperature - partially open, somewhere between freezing (wide open) and 200 degrees F (fully closed). SO I reinstalled the unit.

Just to be on the safe side, I replaced the thermal switch that screws into the expansion tank. I cleaned all electrical contacts, used Stabilant-22 on the contacts, and fired the car back up to check the idle....its still TOO LOW!!!

I have not checked the vaccuum hoses yet, nor have I checked the electricals on the thermal switch (backwards?), but I could use a few more ideas if anyone has them.....

 

An update:

I recently replaced the thermo time switch (threaded into the center of the engine block, just past the oil filter). The car is running worse, rather than better. I have air hoses running through my AAV - how many vaccuum hoses are in a 1984 QV, and where are they located so I can check them?

 

An easier way to cool the AAV is to fill a large Zip-lock bag with ice cubes and wrap it around the AAV "in situ" (with a towel for insulation) for a half-hour or so.
A heat gun or hair dryer could probably be used to test the hot situation. Have done the cold test, but not the hot.

Mark