Tvis question! - MR2 Owners Club Message Board
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post #1 of 7 (permalink) Unread July 15th, 2019, 14:25 Thread Starter
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Tvis question!

Hi everyone, after searching on many forums looks like i canít find an answer to my question so Iíll give a try here! Iíve own my car for 19 years now and for our 20th birthday i want to put her back in shape and bring her to the way Iíve always wanted her. Many years ago a mechanic told me that they used to disconnect the tvis to make more power out of these cars. I noticed back then that i had a vacuum line that was cut and blocked with a screw. Car was running fine and didnít bother fixing that. Now after reading on forums i think that this vaccum line is actually part of the tvis. I looked at different engine bay trying to figure where to connect this vaccum line as i donít see any place where it could connect. I also have a blue connector that is not connected to anything. Just went to toyota this morning trying to figure out with them. Thought Iíve found the piece missing but it was discontinued, so i donít have it. I just lifted the car and looked underneath and i think the part that the dealer said i need, i actually have it! Here is some picture to help understand. Vaccum line and connector are on top of the engine, right by the air intake. Thanks for helping me!
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post #2 of 7 (permalink) Unread July 15th, 2019, 17:36
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Originally Posted by Maustmr2 View Post
... a mechanic told me that they used to disconnect the tvis to make more power out of these cars...

... i had a vacuum line that was cut and blocked with a screw... i think that this vaccum line is actually part of the tvis....

... I also have a blue connector that is not connected to anything...

...Here is some picture to help understand. Vaccum line and connector are on top of the engine, right by the air intake...
Well, that mechanic is a fool. Disabling the TVIS will degrade performance in some range of operation. It is already programmed to select the mode that gives the most torque in any condition. He may be thinking about disabling the EGR, and the two systems are connected.

Not the TVIS. That hose may be from the fuel pressure boost system. That is a whole other story, but it is likely that you wouldn't notice the difference without it. I think that the only purpose was to guarantee hot starting. The fuel pressure regulator should be connected to vacuum, and if it isn't, that would be a good thing to fix.

That might also be the fuel pressure boost.

The TVIS system is entirely under the intake manifold. The vacuum source is a nipple on the TVIS body itself. The only connection to the rest of the system is the hose that goes to the EGR to shut it off when TVIS is activated. There should be a check valve to ensure that the EGR does not feed back to the TVIS
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post #3 of 7 (permalink) Unread July 15th, 2019, 20:43 Thread Starter
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Thank you for the answer, what is that part in red?
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post #4 of 7 (permalink) Unread July 15th, 2019, 21:03 Thread Starter
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ok
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post #5 of 7 (permalink) Unread July 16th, 2019, 16:40
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... what is that part in red?
That looks like the actuator valve for the fuel pressure boost. That system came with the warm climate package. The idea, I think, is to boost the fuel pressure during a hot start to purge any vapor lock in the fuel system. The fuel pressure regulator reference port is normally attached to vacuum to standardize the pressure across the injectors. The valve would switch the reference to atmosphere, which is a simple way to boost the fuel pressure.

Why? You may well ask. I wrote a short essay some time ago with my own theory on that topic.
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post #6 of 7 (permalink) Unread July 16th, 2019, 21:02 Thread Starter
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Thank you very much! Iíve never hear of that before. So what, most mr2s have that connector and itís just not beijg used? Same thing with the vaccum?
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post #7 of 7 (permalink) Unread July 17th, 2019, 16:54
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If the car came with AC, then it also came with the fuel pressure boost. That is what I meant by the warm climate package. The fuel pressure boost could have been removed by a previous owner, and as I said, it is unlikely that you would miss it.
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