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Discussion Starter #1
OK, here's one for you motor heads. As the title attempts to describe (not sure of the exact name of the offending emissions member) I absolutely hate the effect this has on causing the engine speed to hang-up between shifts. I believe it's an emissions thing in response to manifold vacuum (when the throttle body is suddenly closed when shifting or when deacellerating in gear). A valve opens and diverts a small amount of air into the intake manifold after the throttle body. The intent is to lean out the mixture in "overrun" situations to control emissions...and in so doing it causes the rpms to hang up briefly.

I had (and removed) a similar setup on my '87 930, so it's not a new concept. Makes it difficult to time your shifts with a manual transmissions (you auto-tranny guys need not bother with this). I could be wrong, Toyota could be using some other gizzmo to accomplish the same thing (if so, educate me!).

I wish to disconnect or modify how that valve operates, but haven't a clue just exactly where it's located (I don't have a shop manual to point me in the right area). And I'm reluctant to start unplugging things for fear of all the bells and whistles that will undoubtedly go off, only to have to pay some dealer dude to reset everything.

Anybody else in the same mindset as I regarding this PIA. I want my rpm's to drop instantly when I get off the throttle, not hang up there for a second or more.
 

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Discussion Starter #3
I call it throttle hang

The APR X-1 will help you get to where you want it, but as far as getting the rpms to drop instantly, no car does that really.

APR Power - ECU

Call URD if you have more questions about it or are ready to order.:bigthumb:

Underdog Racing Development
Well, "instant" rpm's dropping is just a relative term. At least I would like to see them instantly heading on the downward slope when getting off the throttle.

Thanks for the link to the plug-and-play. May have to think along those lines.
 

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I dont have a fix for the delay in RPM's, but I have an adjustment to help deal with the aggravation.
I found the thread on adjusting the engaging rod under the clutch pedal, I shortened it by 1 1/2 turn's in , it allow's the clutch to engage at the lower end of the pedal and help's to regulate clutch control. It also speed's up the engagement of the clutch which in turn make's shifting smoother .
Love it!!!!
big difference.
Good luck.
when in doubt , throttle out!!!!

:rocker:
 

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Discussion Starter #5
I dont have a fix for the delay in RPM's, but I have an adjustment to help deal with the aggravation.
I found the thread on adjusting the engaging rod under the clutch pedal, I shortened it by 1 1/2 turn's in , it allow's the clutch to engage at the lower end of the pedal and help's to regulate clutch control. It also speed's up the engagement of the clutch which in turn make's shifting smoother .
Love it!!!!
big difference.
Good luck.
when in doubt , throttle out!!!!

:rocker:
That's the first thing I did to my new FJ after bringing her home...adjusted the clutch throw by about 1 turn on the shaft. I hated having the release point somewhere near when my knee is almost in my face.

Still looking into the fix for my original post to get those rpm's to drop sooner.
 

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OK, here's one for you motor heads. As the title attempts to describe (not sure of the exact name of the offending emissions member) I absolutely hate the effect this has on causing the engine speed to hang-up between shifts. I believe it's an emissions thing in response to manifold vacuum (when the throttle body is suddenly closed when shifting or when deacellerating in gear). A valve opens and diverts a small amount of air into the intake manifold after the throttle body. The intent is to lean out the mixture in "overrun" situations to control emissions...and in so doing it causes the rpms to hang up briefly.

I had (and removed) a similar setup on my '87 930, so it's not a new concept. Makes it difficult to time your shifts with a manual transmissions (you auto-tranny guys need not bother with this). I could be wrong, Toyota could be using some other gizzmo to accomplish the same thing (if so, educate me!).

I wish to disconnect or modify how that valve operates, but haven't a clue just exactly where it's located (I don't have a shop manual to point me in the right area). And I'm reluctant to start unplugging things for fear of all the bells and whistles that will undoubtedly go off, only to have to pay some dealer dude to reset everything.

Anybody else in the same mindset as I regarding this PIA. I want my rpm's to drop instantly when I get off the throttle, not hang up there for a second or more.
I hated the RPM hang as well, but got used to it, now I don't even notice it. I don't think there is a fix for this minus a stand alone ECU or maybe a chip in the current ECU could be done. Thing is being throttle by wire you have to get the servo motor on the throttle body to cooperate. Not as easy as the good old days when you actually had a throttle cable. Good luck!:cheers:
 

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Discussion Starter #8 (Edited)
I hated the RPM hang as well, but got used to it, now I don't even notice it. I don't think there is a fix for this minus a stand alone ECU or maybe a chip in the current ECU could be done. Thing is being throttle by wire you have to get the servo motor on the throttle body to cooperate. Not as easy as the good old days when you actually had a throttle cable. Good luck!:cheers:
I suspect you are correct. I've come to the realization that there aint no decel/overrun valve (I'm old school, ok?). It's gotta be the ECU controlling the throttle body servo motor. Not a simple fix.

How about this: Connect an rpm window switch (such as an MSD) that will interrup the circuit to the servo motor, and couple the RPM switch to a simple mechanical switch linked to the clutch pedal. Push in the clutch, the switch closes, it activates the rpm switch which you program to interrup the power to the servo when your rpms are over 2000. So when you push in the clutch, the servo looses it's power and the throttle body closes completely and the rpms drop instead of hang. As soon as you release the clutch pedal, the mechanical switch turns off the power to the rpm switch and the servo then regains it's power and all is as normal.

EDIT: Thinking further, if that TB servo motor is a stepper motor (most likely is) then simply interrupting the power to it will not cause it to reverse back to zero position...I don't think. So my Flinstone Garage work-around may not work at all! Not beat yet....just stumped.
 

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on a side note, I don't think there's much you can do to manipulate the fj's system without getting all the bells and whistles going off :lol:
 
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