1980 GTBi -- do I need this idle vacuum thingy?

Your post is somewhat confusing, because, if you just unplug the wires from the coolant thermoswitch (and everything else is unmodified), this thingy (the cold start air valve) would always be open and you would have a very high idle always. However, if the two unplugged wires are connected together (simulating a closed warm coolant thermoswitch), this would always cause the cold start air valve to be closed (which is how it should be when the engine is warm). But if you want to physically remove this cold start air valve, you wouldn't "run a hose straight through" (as this would let extra air into the engine like it does when cold), instead just physically block off all three hoses (the two large ones and the one small one).

Just for reference, here's how the cold start air valve system is supposed to work -- but often the little vaccum hoses get hooked up wrong to the electrovalve ports, and we've had more than one report of people having the wrong logic coolant thermoswitch installed (later F models use the opposite logic thermoswitch of cold = closed and warm = open) so the below is only true when things are truly "stock":

Cold
thermoswitch in coolant tank = open
which leaves the electrovalve de-energized
which allows the vacuum from the intake plenum to reach the cold start air valve mechanism via the small vacuum lines
which opens the cold start air valve (i.e., connects the two large hoses together) and lets extra air into the engine raising the cold RPM

Warm (when the coolant temp gets to 150~160 deg F)
thermoswitch in coolant tank = closed
which energizes the electrovalve
which blocks the small vacuum line from the the intake plenum preventing vacuum from reaching the cold start air valve mechanism
which leaves the cold start air valve closed so no extra air enters the engine.

 

Yes, physically blocking off the three hoses eliminates the extra air entering the engine via that gizmo regardless of what's going on at the coolant thermoswitch. In fact, with those hoses physically blocked off, you could hook the coolant thermoswitch wires back up and restore the operation of the cold running indicator light in the dash.

 

Not sure about the '80, but would this regulate the cold start injector as well? If so, when you plug the extra air system, you'd need to disconnect that as well to avoid an overly-rich mixture at cold.

 

Go to this page of my website:

http://groups.msn.com/Ferrari308GTSi/1980ferrari308gtsi.msnw?action=ShowPhoto&PhotoID=367

and then hit "next" for the other couple of pictures in the sequence.

Cheers - DM

 

Good thought, but no, this system has nothing to do with the "conventional" cold start system.

Cheers - DM

 

Ah, it's a USA market related device, that's why I don't have it.
If the rest of your cold start installation is identical to the euro-version (just an assumption), why not do away with it altogether?

 

Been a while, but I bought the Euro tube from Ferrari U.K., and then went to a local NAPA store on a slow day and matched up the replacement hose that you will need to "fill in the holes".

When ya gonna come down to Columbus for a meet 'n' greet?

Cheers - DM

 

Trying to follow thinking here as I've had problems in this area, researched it somewhat, fiddled with bypasses, replaced my thermotime, etc BUT this is the first I've heard about a difference between Euro and US cold start plumbing.

Jack (or anyone else) have documentation about one vs the other? Or are you just noting physical differences on someone's car.

This plumbing is guaranteed eventual failure on all injected cars and I feel it needs a wider chapter of knowledge. But I don't like the idea of excising portions of the plumbing. If lower cold idle is desired it can be accomplished by choking down the airflow. And can be kept at new standards of operation without much effort. Otherwise the car would eventually be a lump and 3 wheels.

 

To ensure clarity, the feature that Tony and I (plus others) have been discussing in this thread is a crude (USA market specific) attempt to meet the smog requirements of the early 1980’s.

As I understand it, the core issue in that day was excessive exhaust emissions while the engine was cold and idling. The “fix” for this situation was to equip the engine with additional components which, immediately upon starting, ramped the idle speed of the stone-cold engine up to something like 3000 rpm. Upon the warming-up of the catalytic converters, which typically would take around 5 minutes or so, the idle would then return to a normal 1000 (+/-) rpm.

This is –not- related to the conventional cold start circuitry which all such F.I. engines have, but it is a separate addition to this.

In fact, it is my belief that this ill-fated cold start idle feature is a key cause for the oft-repeated anecdotal complaint that these engines burned oil when new. Common sense would dictate that revving a cold engine in this manner would be a pretty bad idea. It is my hypothesis that this excessive engine wear when cold was the primary cause behind the reputation for burning oil that these engines now seem to carry.

Back in the day, many new owners would simply disable the task-specific coolant temperature sensor which triggers this system, thereby “tricking” the engine into thinking that it is already warm, and thus offering a conventional low idle speed at all times.

What Tony originally asked about was the feasibility of removing these non-functioning components from the engine (in the name of a less cluttered engine compartment) since this feature had since been disabled, per the paragraph above.

Personally, as with all such deviations from OEM that I make, I carefully document the removal procedure (see the link to my website that I posted earlier, as one example) and safely label and store the removed components in a box. Should I ever decide to sell the car, reinstallation for all such items for a new “purist” owner would thus be straightforward.

Cheers - DM

 

Why not just fix it right and do away with the anxiety of having the knowledge you have to fix it before you go to the smog shop?
I really think that there have been some major advancements due to the "necessary?" emissions laws imposed by California (always stricter than other states) which get adopted to improve the efficiency of the engines mixed with the consumer demand to make it go faster.
Now you have 600hp engines that you can stand behind and not get asphyxiated.
Fix it right when you can.
And thanks for all the help on this subject. It seems many of the posts when the 3 liters get older are having to do with this subject. ALL inputs are appreciated by the non-pros (or intermediate enthusiasts) like myself. IMHO

 

Although I do agree with you in principle, the US cold-start stuff would be the first I'd throw off my car if I lived in a state where it wasn't deemed necessary by the sniffer demons. At a cold start I like to run rpm's at a level that just makes the engine run nicely round, and not put excessive wear on cold internals by high rpm'..
Some of us live in climates where the cold start installations are not needed at all, and I see no reason why, in that case, it shouldn't be disabled.

 

Actually, I agree with you wholeheartedly. But with a system this complicated, it has been pointed out in earlier posts that many will do mods that are either incomplete or that disable one part of a system while affecting another and has overheating cats or bad idle performance, many other complications on a system that relies on proper input of information.
I think the important you made was to properly document the mods that you make so that unintended consequences can be reversed without much damage (hopefully).
I'm not worried about choking behind a car without proper emission equipment, just that Ferrari went to great lengths to build a system that did what 454 Corvettes couldn't (yeah, I know they were cheaper). The high RPM is truly a problem considering the studies that say most engine wear is experienced at start up but when I was first working with big diesels, an older mechanic would start the rigs at a higher idle. I always thought this was taboo. When I asked him about it, he said that it was better to have a higher idle on start-up because the oil got to critical components faster and that the engine load was not as detrimental as the longer period it took for the oil to get to these components. He also never used starting fluid but a gas soaked rag (probably outlawed now and not much fun when it's cold) to help hard starting diesels. Later, a highly trained service mechanic told me that Peoria (where many Cats are manufactured) had done studies and found this to be true with Cat diesels because the tolerances on Cats are not as tight as, say Cummins diesels, and that the slightly higher idle at start-up was a better procedure and told me about the "addictive" nature of ether on diesels. (Any Cataholics out there?)
Truth of BS? I cant remember reading about that testing anywhere but it's an interesting theory and with Ferrari's having aluminum engines, possibly a quicker warm-up is better than a slow one.
I understand that the instructions for new Ferrari owners of this year 308s was that you don't drive the car until the warm-up light is off (got that from an old boy that bought one new). Most people, I feel, don't wait that long; but I do. Maybe it was to shorten the warm-up cycle for impatient drivers.
I'd love to hear from the technical crowd because this is how I formulate my own philosophies. Not trying to stir up any s**t, just trying to learn.
Sorry, even I have trouble justifying my arguments sometimes but just make sure you don't screw something else up to save proper diagnosis of an engine problem. It was a great design for the time it was built in.
I hope I haven't gone too far off thread.

"A Ferrari is a terrible thing to waste."

 

Well, I don't think I'd go quite so far as to say that!

I'd say instead that the 3000-rpm-idle-when-cold components were really a stop-gap, half-baked, cobbled-up, ill-fated attempt to address the USA specific smog laws of the day.

I believe that this fast idle is responsible, at least in part, for the reputation that cars like mine have earned as oil burners.

The fact that later cars don't have this feature is evidence in my mind that a better solution was ultimately found to address this issue.

Cheers - DM

 

It is difficult to compare diesels with petrol engines, as they work on different a/f principles.

Apart from wanting lubrication from cold oil, the following is an important factor:

One of the things that are bad in a petrol engine at cold start is the overly rich mixture to get it started and the incomplete burning. This leaves residue, which does not lubricate (valve-stems, cylinder walls) and contaminates the oil.

Once the car is in motion, you are making much more energy than with an engine running without ballast at equal RPM's, and thus you produce more heat. The quickest way to safely warm up an engine is to drive your car.

Law-makers don't always get it right, and we know better now, but think of all the petrol that was wasted by lowering compressions for the use of lead-free petrol, and all the emissions gear that we trucked around for all those years, most of which didn't work properly after 2 or 3 years anyway. Look at how many cars burnt out because of smog equipment.

Today we have great solutions to replace the system we are discussing in this thread; yes, there's something to be said for originality, but there is no way in this world I'm going to let my cold engine idle at those high rpm's.