Idle and throttle plate setting???

[skishop69]

I have the procedure for setting the idel on the 88 EA82T MPFI, bt since it was screwed with before and after I got it, I need to know if anyone has the specs for setting the throttle plate stop screw. (some of you might call it the 'idle' screw) I know the throttle plate has to be in a specific spot so you can set the idle switch for 1.5 degrees then adjust the idle air screw on top of the throttle body. Specs anyone?

[daeron]

I am not the know all see all on this.. but my understanding is that there IS no "procedure" since it is something that is never to be touched.. Sorry to be the first to say this.

 

Keep your fingers crossed.. If I AM wrong, then my posting here saying "nah, you can't do it" is probably the surest way to encourage someone to post up making me stick my foot in my mouth again :-p

[cobcob]

I would think there HAS to be some proceedure for setting it correctly, I noticed on my 88 GL-10T wag last night that the screw stop does not even contact anything in its current position, it's obviously backed out at some point in the past 20 years... Probably a part of the reason why this POS won't idle...

I haven't run across any documentation that mentions how to set it correctly though, all I've been told is "NO TOUCHY THAT SCREW!"

[j2coe]

do you think it has to be adjusted to the engine, or if one of us can measure the length on one thats set currently with a caliper it would at least be a good start?

[hooziewhatsit]

Looking in the FSM I have ('85), the throttle is 'closed' if it is 2* (or less) open. So, I believe the stop screw needs to be set to leave the throttle plate open by 1.5* or so. Basically, so the plate is barely open.

 

Then, you will want to adjust the TPS so that one set of contacts is connected until you open the throttle 2.5*. After that the contacts should be open (not connected). (the '88 TPS may be different than the '85??)

 

The other contact on the TPS should then be connected when the throttle is opened beyond ~45* past that.

 

Then, for SPFI, it says to disconnect the idle air controller, and adjust the idle to 550rpm. Then when you reconnect the idle air controller, it comes up to the 700+- 100rpm. (may be different for MPFI)

 

I'll try to remember to take my friends car apart today to see how open the throttle plate is. (85 turbo). On my two SPFI wagons, the stop screw is set to leave the throttle just barely open.

 

-Dave

[Ross]

Its function is to hold the butterfly valve so that it is just short of being completely closed - simply to stop the valve sticking in the bore.

 

As such, to adjust it, just back it right out so that the butterfly sits on the TB bore, then wind it in maybe 1/4-1/2 turn so that it holds the valve off the TB bore walls very slightly. As long as it is within the 1.5degree allowed by TPS and it holds the valve off the wall, the exact adjustment is NOT critical (contrary to common belief...).

[skishop69]

Ross, you are correct. I got hold of an older Subie tech, and that's exactly what he said. 1/4 to 1/2 turn in form no contact. It DOES make a difference where the throttle plate is set. Incorrect setting can result in hesitation, surging and improper idle (according to him). I got it handled and it also helps if the PCV line in the air tube after the MAF is plugged in too. Can't believe I missed that. Doh! She runs great now. Thanks guys.

[daeron]

Ross, you are correct. I got hold of an older Subie tech, and that's exactly what he said. 1/4 to 1/2 turn in form no contact. It DOES make a difference where the throttle plate is set. Incorrect setting can result in hesitation, surging and improper idle (according to him). I got it handled and it also helps if the PCV line in the air tube after the MAF is plugged in too. Can't believe I missed that. Doh! She runs great now. Thanks guys.

 

Awesome, this is the first I have read anything about "proper" dickering with this screw. Thanks for the update.