Broken TVSV

General discussion about our beloved Tercel 4WD cars
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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Broken TVSV

Post by Petros »

a more simple alternative would be to by pass the TVSV all together, rig it so it runs in the equivalent of the "warmed up" mode, and if necessary, use a manual switch for cold running condition.

Back before government regulations, in the early days of automobiles, the driver had to constantly adjust the spark timing, and the mixture, as well as the choke during cold running. Many of my first cars had manual chokes, as it warmed up you pushed the choke knob in to reduce the amount of choke. I did not like the first car I got with an automatic choke, I could not control the mixture nor adjust for different air temps.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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rer233
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My tercel:: Multiple

Re: Broken TVSV

Post by rer233 »

Exactly what my lash-up does. When the engine's cold, I flip the rocker switch to the "on" position (it lights up then) which sends power to the switch over valve routing the vacuum like the tvsv would in a cold engine. When the engine temp gauge moves off the "cold" peg, I flip the switch off, de-energizing the valve and routing the vacuum like the tvsv would in a fully warmed-up engine. This doesn't allow the "intermediate" setting of the tvsv, but I haven't had any driveabilty problems.

As for hand chokes, I fully agree with Petros- always did like 'em. In fact I probably owned one of the last of USA smog-legal cars imported here- a 1983 Renault LeCar. Actually, I've owned a bunch of 'em- 1983 was just their last year here.
if it aint there, there's a good chance it won't break!
83 SR5 Silver/Blue (Snowmobile/work beater)-totaled but drivable
85 SR5 Blue
88 SR5 White (the 'good' one)-not anymore-totaled
87 fwd silver wagon a/t
87 4wd dx Cream (a/t- not anymore- now m/t)
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Mark
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My tercel:: 1984 Automatic, 1981 sedan
Location: Victoria, B.C.

Re: Broken TVSV

Post by Mark »

I think if I had to, I'd be fine bypassing the TVSV and it's related systems. The AAP I don't use anyway (mine are disconnected and capped off). The choke breaker linkage could somehow be rigged to constantly hold the choke slightly open at startup. I don't think the second or so when the choke is completely closed on startup makes much of a difference anyway. The EGR system is often disabled anyway by some people, but I might be cautious about the increased cylinder temps and possible effects on valves. There is a line going to a vacuum switch for the computer and I don't know what the computer does with that signal. It might open or close a fuel solenoid or something important like that.
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lannvouivre
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My tercel:: 2006 Pontiac Vibe
Location: Odessa, TX

Re: Broken TVSV

Post by lannvouivre »

Petros wrote:I did not like the first car I got with an automatic choke, I could not control the mixture nor adjust for different air temps.
The best thing about newer cars is that they can do these things themselves, correctly, and in a very wide variety of conditions with great accuracy (for the most part). I'm pretty impressed with how much Toyota did with such primitive tech on the Tercel, but the approaches engineers and programmers have polished up over the years with testing and tuning are shocking at time. Even some aftermarket parts manufacturers are pretty sophisticated now.
But...did you try hitting it with a hammer?
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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Broken TVSV

Post by Petros »

I agree, modern systems are much more accurate and reliable than early mechanical auto chokes. Most of the first autochokes were garbage, manual choke was much better and reliable.

Emissions systems demands have resulted in the modern designs, and on most of the Japanese cars, are very reliable and have little to no maintenance requirements. My Nissan I drove to 380k miles and the only service I did on the fuel system was change the fuel filter, and dump a can of injector cleaner in the tank once a year. Similar experiance with our mazda.

Newer systems have become unreliable unfortunately, mostly because of unreasonable demands for both higher fuel economy and lower emissions by the federal government. it comes at great cost, I think the best EFI Systems are from about 1994 to 2004, and the newer you get the less reliability you will get.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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