Adjusting Idle switch 91-94 TB

[tarantula]

I bought a 91-94 TB. I wanted to clean it up real good so I proceeded to take the stuff off. Not knowing that the Idle switch was two parts I unscrewed the big Jam nut and was like "Oh shit What have I done.?!!?" Now I am still going to clean it up real good but I need to know how do I adjust the idle switch when I replace it. I know that I'm not going to use it but wanted to know because It holds the throttle plate open a tad, so it won't scuff the throttle bore. I know that if it were to die on a 1G theres a replacement. And there has to be a procedure to set the new throttle stop switch. What is that procedure?
Thanks.

[tarantula]

Since No one had information helping on this subject I figure I will put this information that I found for all those that has the same situation and have to adjust their own 1G Throttle switch. Maybe no one really knew how but as I have learned I want to share. Heres one quote:

You adjust the IPS until the switch closes and then turn it 15/16 of a turn farther in and lock it down. Since this sets the amount that the throttle plate is held open at idle I tweek it a bit depending on how sensitive the rest of the bypass adjustments are to surging. The tweeking being very small positioning changes the final 15/16 turn adjustment.

Steve

Heres another quote taken from a book.

If adjustment is required, turn OFF and slacken the accelerater cable. Start the engine and adjust the idle speed using the Idle speed adjustment screw. (BISS) When making the adjustment, use a hexagonal wrench in order to prevent play caused by backlash. ( I don't know what this has to do with the biss screw. they probably referring to the idle speed switch) Check the engine idle speed and compare to the desired specifications of 700-800 rpm.
Once the engine RPM is set, screw in the Fixed Idle Speed adjusting screw (SAS) until the engine speed starts to rise. At this point return the fixed idle speed adjusting screw to find the point at which engine RPM does not change. Once at this point, turn the fixed idle speed adjusting screw in a half turn. Turn the engine OFF. Adjust the accelerater cable and the throttle position sensor. Start engine once again and let idle for 5 minutes. Check to be sure the idling condition is normal and that the engine speed is correct.

I'm hoping this helps. I will be trying this later this week and will post my results.

[cbilmer]

Interesting...

I didn't take mine off, but I did adjust it somewhat by accident thinking I was supposed to take it off. I caught myself before I took it off too much.

To get it back to where it was supposed to be I just screwed it down to where the throttle plate barely touched, and then backed it off just a tad. So there is just a thin line of light if you hold it up to a light bulb(probably less than one millimeter). It seems to be working properly. I've been running it for at least a month or so now.

Good luck,

Chris.

[tarantula]

Well What worked out was the first method with the 15/16th turn. Than I adjusted the TPS. using the following quote:

2G's critical TPS adjustment is the Idle Position Switch that's part of the TPS.
(2G TPS pins are 1- 5v, 2- TPS output, 3- IPS output, 4-ground)

You place a .0177" feeler guage between the stop screw (fixed SAS) and the throttle pulley to open the butterfly and then adjust the TPS right to the point where the IPS (pins 3 and 4 on the TPS) switches from closed (0 ohms) to open (infinite ohms). Then you verify that the TPS (pin 2 and 4) reads between 0.4 and 1V while the feeler guage is still in place. Anything in that range is ok as long as the IPS is adjusted correctly. It it's not correct you need to check that pin 1 is about 5v and pin 4 is grounded. If they are not correct then the TPS is bad.

There is no way to adjust the TPS voltage independantly of the IPS on a 2G. Trying to correctly set a 2G TPS by voltage will only work by dumb luck.

Now I'm happy.

[trev0006]

Thanks for posting this, we where having the same problem until we found your post.

Originally Posted by tarantula

Since No one had information helping on this subject I figure I will put this information that I found for all those that has the same situation and have to adjust their own 1G Throttle switch. Maybe no one really knew how but as I have learned I want to share. Heres one quote:


You adjust the IPS until the switch closes and then turn it 15/16 of a turn farther in and lock it down. Since this sets the amount that the throttle plate is held open at idle I tweek it a bit depending on how sensitive the rest of the bypass adjustments are to surging. The tweeking being very small positioning changes the final 15/16 turn adjustment.

If adjustment is required, turn OFF and slacken the accelerater cable. Start the engine and adjust the idle speed using the Idle speed adjustment screw. (BISS) When making the adjustment, use a hexagonal wrench in order to prevent play caused by backlash. ( I don't know what this has to do with the biss screw. they probably referring to the idle speed switch) Check the engine idle speed and compare to the desired specifications of 700-800 rpm.
Once the engine RPM is set, screw in the Fixed Idle Speed adjusting screw (SAS) until the engine speed starts to rise. At this point return the fixed idle speed adjusting screw to find the point at which engine RPM does not change. Once at this point, turn the fixed idle speed adjusting car screw in a half turn. Turn the engine OFF. Adjust the accelerater cable and the throttle position sensor. Start engine tire once again and let idle for 5 minutes. Check to be sure the idling condition is normal and that the engine speed is correct.

I'm hoping this helps. I will be trying this later this week and will post my results.

[tarantula]

Originally Posted by trev0006

Thanks for posting this, we where having the same problem until we found your post.

Glad to be of help. Your welcome!

Just for the record, to date I have had no problems since that day in 2005 when I posted that information. My car works flawlessly with those adjustments.