Here are pics showing what should be the results of testing at various temps
The results I got are as follows -
Did not test by cooling to below 7C (45F) as with both TVSV's at room temp, the below 45F/baseline condition was already present.
Both TVSV's switched to the 17C-50C (63F-122F) condition at approx 102F, and both switched to the above 68C (154F) condition at approx 173F. The '86 unit switched a few degrees sooner, in both cases, than the '87 unit. A bit high, compared to what a new unit would likely switch?
There was a problem though, with both units, at both switching points, and the '87 was far worse, so it got taken out of use and the '86 installed in its place. Incidentally, both units are from vehicles with approx 250,000km/150,000 miles on the clock.
The problem was this, that at both points, there was a transition range of close to 5 degrees F ('86 unit) and closer to 10 degrees F ('87 unit) where BOTH the 'K' (vacuum port) AND the 'J' (atmospheric port) were connected simultaneously to whatever port they were supposed to be switching away from/switching to. Bottom line = there was a vacuum leak from atmosphere (J) to vacuum (K) during this transition time. In the case of the '86 unit the 'leak' was very minimal, but in the case of the '87 unit the 'leak' was very considerable, and lasted longer, to boot.
Another thing I noticed with both units was that the vacuum port 'K' did not totally 'disconnect' from the AAP port 'N' until approx 190 degrees F. This means that the AAP was still functional with a quite warm engine = unnecessary richness beyond where necessary/desireable? As it appears (with my massive sample of two TVSV's) that a common failure mode (with age) of the TVSV is that all switching functions tend to move to higher temps, that in an extreme case of this type af age-related 'failure', one could end up with a condition where the AAP is always active = excessive fuel consumption on acceleration/overall poorer gas mileage, even with a brand new carb installed?
I've temporarily plugged my AAP vac line, as another member mentioned doing in one post, to see if it really makes any difference when the engine is cold. In my case it doesn't seem to have done anything too much, but temps are above freezing right now, and we seldom get extremely cold weather. Will be interested to see how it goes if we get a cold snap.
Another thing I found in my case, was a leaking CO (Choke Opener) diaphragm = questionable/erratic EGR operation? - as the CO and EGR line both come off the 'M' port of the TVSV.
For now, I have temporarily plugged off the line to the CO as I don't have a spare to install. And, in fact, it makes no difference running with the line plugged as my choke still opens fully anyway. The carb on my '86 parts car doesn't even have a CO, just the CB (choke breaker) and heated electric choke.
Bottom line - TVSV - potential big problem (especially if you have to pass smog) - but how necessary is it?
If the diaphram is OK...then full manifold vac should keep it OFF....or maybe just remove the spring.