I have written a little article on the cold start valve for us USA spec owners. http://www.birdmanferrari.com/service/cold_start/cold_start.htm I get a lot of questions asking about how to disable this annoying thing, so I thought I would just do a write up. Birdman
good write up Jonathan, but I would rather call that thingy a "cold start air valve" ... just to make a clear difference to the "cold start valve" on the right side of the plenum which is a usual part of the K-Jetronic and injecting additional fuel on cold start up
I had the same thought. Even though the other one is usually called the "cold start injector", it is still confusing at first. I would call this thing the "cold start electrovalve"
http://ferrari308gtsi.multiply.com/photos/album/2/1980_Ferrari_308_GTSi_2003_2008#photo=108 plus the next two (2) pages beyond this. Enjoy - DM
You are correct of course, but to avoid even more confusion, I'm calling it what the Mondial service manual calls it. I didn't make up the name! Ironically, the REAL cold start air valve is called the "Auxiliary air valve." THAT's the part that all Ferraris have. The "Cold start valve" (the USA-market only emissions-gadget which is the subject of my article) should be called a "fast idle valve" or an "emissions valve" or maybe "race your engine until it wears out" valve! Birdman
Nicely done Dave. I didn't know that existed. Mine explains it better I think, but I really like your pics!!!
Birdman -- The logic of the US 308i-2V coolant tank thermoswitch is cold = open and warm = closed (that's why people sometimes "jumper" the two wires closed to always force the warm-running condition on those models). Note the two ports where the vacuum lines are connected on the electrovalve in your diagram and in Dave's photos -- ports 1 and 2 as labeled in this jpeg: Image Unavailable, Please Login The logic trail is: coolant cold = coolant thermoswitch open = electrovalve unenergized = port 2 connected to port 3 and port 1 blocked = no vacuum reaches cold start air valve diaphragm chamber (and cold start air valve diaphragm chamber is vented to atmosphere) = cold start air valve open = extra air enters engine = high idle RPM coolant warm = coolant thermoswitch closed = electrovalve energized = port 1 connected to port 2 and port 3 blocked = vacuum reaches cold start air valve diaphragm chamber = cold start air valve closed = no extra air enters engine = normal idle RPM
Hey Steve, Interesting! There must be more than one setup then. The info on my web page comes directly from the Mondial QV service manual and matches the set-up on my Mondial QV. I would be curious to see the "schematic" for the 2V so I can post a 2 V update. I'll look at the 2V service manual too. Net result is the same though. You need a vacuum at all times on the cold start valve to keep it closed, or remove it entirely. Birdman
The text in WSM 281/83 on page D59 describing the operation of "sensitive switch 7 Fig 44" is just wrong (as is the text at the top of page D60 which says applying intake manifold vacuum causes the cold start air valve to open -- which conflicts with Fig 48). Note that the further text on page D60, which also describes the operation of "sensitive switch 7 Fig 44", is the exact opposite of that on page D59. To convince yourself just measure the resistance between the two terminals on your coolant thermoswitch (even if you've removed the rest of it). Unless someone has wrongly replaced it with the later 328 coolant thermoswitch , the logic should be cold = open (infinite ohms) and warm = closed (maybe a few ohms).
Hey Steve, I just went out and double checked the switch in the coolant tank of my Mondial and it is indeed OPEN when cold. Which means that the Mondial service manual is INCORRECT on the "logic" of the system. I will correct the write up for that part tomorrow. Good catch! It has been YEARS since I disabled the system and my memory of the switch polarity was apparently greatly influenced by the service manual! Damn Italians! Birdman
There are some real problems in understanding this simple circuit. The offending fast idle is only used early US cars with basic Bosch K injection, i.e. NON-LAMBDA injection. There are NO errors in the manuals in this regard, only in realizing this distinction. The expansion tank thermoswitch on US 308 NON-LAMBDA injected cars is CLOSED below 122°F (±4° F). This switch also causes the yellow (gtbi gtsi) or orange (Mondial) dash lamp indicating 'cold engine' to illuminate. Later US 3x8 QV cars (i.e. with lambda injected engines) also have a thermoswitch but it's function is coincidental and reversed, OPEN below 135° F. These cars have no 'cold engine' dash light nor fast-idle circuits. The thermoswitch function affects FI circuits, fast idle components don't exist. Jonathan, you might change some minor wording problems, for example, the thermoswitch does not SEND 12v to the electrovalve. The electrovalve already has 12v from the ignition key. The thermoswitch simply provides a ground to enable it. etc etc Also, you are welcome to use my electrovalve diagram, below. A vacuum diagram showing tubing would also help but I'm not volunteering. I strongly disagree with advocating disabling the thermoswitch by disconnection (#2 option) on 2 counts. Someone with a lambda car will misunderstand and induce problems. Secondly, it disables the innocuous dashboard 'cold engine' light for no good reason. Granted part removal is popular, vis-a-vis air pumps and cats, but an easy and constructive fix is simply constricting the air flow to reduce idle to 1200-1500 rpm. J, your site has become a valuable must-read. Image Unavailable, Please Login
All, IF memory serves, somone here recommend putting a piece of wood (round dowel) with a small hole in it, inside one of the hoses. This would allow the system to function, but the size of the hole in the piece of wood would determine the Fast Idle rate. Smaller the hole the lower the Fast Idle. Does anyone else recall the details to this mod and is it a "Viable" solution?
yes, by inserting a small tube, you can reduce the diameter of the hose connecting the "cold start air injection valve" to the "T" of the "auxiliary air valve" (AAV)... thus, as Paul suggests, restricting the airflow to the plenum and reducing the rpm to a more reasonable 1800 - or less if you wish (depending on the diameter of the tube) see (bent) upper hose of the "cold start air injection valve" (probably also works if you take the lower piece of hose?) . Image Unavailable, Please Login
there is no "fast idle system" on a 328 - you only have the "auxiliary air valve" AAV (near the expansion tank)... wich is open on start up to let additional air in...and than slowly closes when warm (bi-metal...heated by either a) electrical contact and/or b) sourrounded water tank/engine heat
Hey Paul, while the manual agrees with you, the fact is that when I measured the switch on my coolant expansion tank, the result agrees with Steve's assessment. Mine is OPEN when cold. Furthermore, looking at the diagram you posted of the electrovalve, it clearly shows that the valve needs power to be open. When it is open, it provides vacuum which closes the cold start valve and disables the fast idle. So the switch in the coolant tank would have to be CLOSED when warm (OPEN when cold) to work. I think Steve is right on this one! But your other point is clear....there is a big difference between the lambda and non-lambda cars. Will fix that! My "send" 12 V comment was meant to simply simplify the operation of the circuit to non-electrically literate. Maybe I oversimplified. I'll change the wording so as to not be confusing to the nerds. What a can of worms!! As for putting dowel in to reduce the effect of the cold start valve...I wouldn't do it. You don't need this circuit at all, there is no reason to keep it functional. Birdman
I have made an attempt to correct the article to include all the new information. It sounds to me like there is a possibility that some cars have a circuit that have the logic one way (cold expansion tank=open switch) and other cars have it the other way (cold expansion tank=closed switch). Both the switch and the electrovalve would have to be backwards for this to work. As a result, I have changed my article to reflect that if someone wants to use the electrical circuit to disable the cold start valve, they need to check which way it works first. But we all agree, that's the worst way to disable the cold start valve. The best way is just to remove it and plug the hoses that lead into and out of it. The second best way is to just run the vacuum line from the plenum directly to the valve, forcing it to stay closed whenever the engine is running. The annoying thing about this valve is that it requires vacuum to stay CLOSED and therefore defaults to the open condition if there is a failure of any component in the vacuum system. UGGH, very bad design. I would like to hear from anyone that has a coolant expansion valve that is CLOSED when cold. Paul's schematic analysis and the service manual both indicate this is how it works. However Steve insists the manual is wrong, (and Steve is frankly rarely wrong). And my tests on my Mondial show Steve to be correct, at least with my car. Paul's diagram of the electrovalve agrees with Steve. Other data points would be nice! Thanks for the constructive feedback Paul, Steve and everyone! Birdman
This is a good point. If your car has the dashboard light, it serves as a reminder not to rev the car too much until it goes out. Disabling it along with the cold start valve is sort of a bummer. Hence another reason that the "electrical" method of disabling cold start valve is not the best option. On the other hand, the light will go out once the coolant reaches 50 degrees C (120 degrees F) and that is not warm enough for the engine to be revved freely. So when this light goes out, it gives a false sense of security that the car is now "warmed up." It's not. You need to watch the oil and water temp gauges for that!
My 1983 Mondial QV (definitely non-lambda) has an OPEN expansion tank switch when cold and no dash light. So there are definitely some weird things going on here!
stealing Dave`s picture from his excellent site, see those two hoses . Image Unavailable, Please Login
I am very sorry buit I am a Dumb-A$$ on this one. Can you put an arrow in that pic that shows where to place the insert. I recall it going into one of the BIG hoses in that pic, but I could be wrong. I have killed a few brain cells since then.
To change the rate of air flow I just use an old injector bushing inseted just before plenum and then open the id hole a bit if needed - seems like a simple fix - the cold idle is around 1500 now - seems just about right - Wayne
