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173 Posts
Discussion Starter #1
just got my supra for 2 week now... i use to own a turbo IS300.......

when i get on my supra.....it's lagging all the way to 5300 rpm......and then at 5300rpm it feel like vtec kick in or something and haul ass....is this normal??my is300 never did that...but it was vvti though....

and sometime when it idle...it goes up and down.....

thanks
 

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wasting my life on SF
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1,808 Posts
well at idle...i woudl guess that that is the "choke" or cold start mode.

as for the "VTECH" i think you might have about the same thing that i have in my na, its dog slow then it gets slightly less slow, but its still gay ass and slow...

thats just an NA supra.
 

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Discussion Starter #5
is there a way to stop the choke...it's usually happen after it's already warm up...mainly after a long drive....
 

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EZ2CYI1
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875 Posts
There is a butterfly inside the plenum of the intake manifold, I don't know much about it except that at some point it opens up all the way under vacuum.

I've noticed a slight "kick" at ~4000+ RPM in mine (92 SC300 5-speed) that I just figured was due to that, but hopefully someone who knows more about it will chime in here.
 

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Exiled Supra Owner
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3,703 Posts
The reason for the surge in power:

There is a butterfly inside the intake manifold that is opened up by a vacuum switch at around 4,800 RPMS. You will feel like a VTECH kick feeling, but the reality is just more air and fuel is being dumped into the cylinders.

As for your idle issues, it can stem from a number of issues (listed from the cheapest to most expensive in price to fix):

1. Check to make sure there is no vacuum leaks on the intake manifold, hoses, and air filter box. Sometimes there are dead rats in the airbox.
2. Adjust the throttle positioning sensor.
3. Check the engine timing of the car. You will need a timing gun to read the timing degree mark on the crank pulley when the car is warm. It should be at around 10 degrees @750 +/- 50 RPMS at idle.
4. Clean out the Idle Air Controller. Sometimes they go bad, but cleaning usually works.
5. Check if the MAF sensor is clean.
 

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feeding your habit
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you're lagging because you have no turbo.... check my sig.
 

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Newbie
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11,221 Posts
Change the spark plus. It's a cheap and easy thing to do (well easy for some on the NA's :lol: ).

What's it idling at? I'd look at bumping up the idle to overcome the rough idling.

NA's were always slow. What does the torque curve look like on the NA?
 
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