What does this do?
Refined Valley Dude
Joined: Oct 2001
Posts: 2,283
Likes: 2
From: Kitchener, Ontario (Hamilton's armpit)
Something to do with the idle. My idle was rough ealier this year and my mechanic gave that screw a few turns and it smoothed things out.
Just flipped through the Haynes manual (pos but I didn't feel like nosing through the FSM...) Page 133. If that's it, then it's the fast idle adjusting screw.
Hope that helps...
Amur_
Just flipped through the Haynes manual (pos but I didn't feel like nosing through the FSM...) Page 133. If that's it, then it's the fast idle adjusting screw.
Hope that helps...
Amur_
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Senior Member
Joined: Jun 2001
Posts: 327
Likes: 0
From: san francisco,Ca
you know how when you first start your car in the moring it revs itself up to like 2k? (kinda like a choke) that screw adjusts how high it goes. if you want it to idle at 4k tighten the screw a little.
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 27
From: FORT WORTH, TEXAS,USA
Fast idle screw. It works with the cam adjusting screw to set up the idle when the engine is cold. You have done the *throttle body modification* which removed the thermowax, which in turn means the fast idle screw is totally wothless. Might as well throw it in the garbage can. Non functional. Extra weight.
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 27
From: FORT WORTH, TEXAS,USA
One stop screw stops the primary throttle plates shaft, the other stops the secondary (two plates) shaft. If you've done the throttle body mod, I suppose you use the stp screw for the primaries to crack the plates so you can have an idle of sorts.
Thread Starter
Nothing to see here.
Joined: May 2001
Posts: 1,255
Likes: 1
From: Jacksonville, FL
HAILERS— I have the throttle body sitting here and I'm looking at the throttle stops. The one near the TPS controls the top two plates and the other adjusts the bottom plate with the hole in it. I guess the one with the hole in it is the plate that is used during idle and low rpm driving. Why would someone adjust the top plates? If you're adjusting your idle, wouldn't you want to only adjust the bottom plate? Aaargh! Here's another post on this subject that I'd like you to look at:
https://www.rx7club.com/forum/showth...threadid=74510
I guess my biggest question is: If you've done the throttle body mod, what clearance should there be on the bottom plate at idle? Mine is fully closed and with all the other variables in setting the idle gets to be very confusing. Thank you for your help!
B
https://www.rx7club.com/forum/showth...threadid=74510
I guess my biggest question is: If you've done the throttle body mod, what clearance should there be on the bottom plate at idle? Mine is fully closed and with all the other variables in setting the idle gets to be very confusing. Thank you for your help!
B
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 27
From: FORT WORTH, TEXAS,USA
Sorry, never done the throttle body mod and probably never will. I figure you can't use the mauals settings because you removed the thermowax and made those adjustments invalid for a car with the throttle body mod. OOOOOps. Yeah. The stops I got backwards as to which goes to which. I take it that you can't adjust your idle with the bac to meet 750? Right? No vac leaks and it does not get better when warmed up???? Frankly speaking if that the case, I see nothing wrong with using the throttle stop on the front to adjust the idle up where you want it. Does your bac make any difference at all???? How about when you unplug it. Does the idle drop a touch?
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 27
From: FORT WORTH, TEXAS,USA
Oh! I did not look. Your car does not have an adjustable bac. Oh well. How about working with the variable resistor?? Have you tried that yet? Is the timing spot on? What is your idle right now with it warmed up?
Thread Starter
Nothing to see here.
Joined: May 2001
Posts: 1,255
Likes: 1
From: Jacksonville, FL
HAILERS— My BAC works. I replaced the transistor in the ECU and I CAN adjust my idle with the BAC. I'm just not sure if I should be using my BAC or the Idle Set screw on the plenum. I can adjust my idle with the BAC, the idle screw on the plenum, either of the throttle stop screws or even the dashpot. I just would like to know which combination and which order to do so. As I said,VERY confusing with so may idle variables in play. Thanks again.
B
B
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 27
From: FORT WORTH, TEXAS,USA
M ignorance. I had no idea the 87 bac were adjustable except if you did some unauthorized fiddeling with it. Shouldn't have to use the throttle stop screws in that case(bac and pleneum screw work). Shouldn't be using the dashpot to set the idle either. I can make a jpg of the manual procedure later today. Its basicaly jumpering the initial set coupler, setting the timing(really can be done without jumpering the initial set coupler), turning the screw on the plenum for the correct idle. Sometimes if that can't get it , you can adjust the variable resistor to help. Since you have an adjustable bac (I'd of swore those 87 na did not have one) you could use that also. There is a procedure for setting the moment that the secondary throttle plates are supposed to move. I'm not sure at this moment if removing the thermowax etc (throttle mod) effects that or not. To set the idle you shouldn't be messing with the throttle stops or the dashpot(except under extenuating circumstances). Later with the jpg. Work to be done now. Bottom line is the plenum screw is the one to use.
