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Discussion Starter · #1 ·
Been doing lots of repairs here and there on my 89. PO had a large spring going over the valve cover to return the throttle to idle. I pulled it off seeing there was a return spring on the throttle body. Removing the additional spring resulted in throttle not returning to idle but sticking open and keeping RPMs around 1500. There was also a zip tie on the spring on the throttle cable that seemed to reduce the travel of the spring/cable. Can't tell if it was really making a difference. Once I put the extra spring back on (across VC), the mechanism returns to the idle stop screw (without the zip tie on the cable spring).

I had already done some cleaning on the upper half of the throttle body and didn't see much buildup that would prevent the butterfly valve from returning to the idle position.

Is the return spring on the throttle body insufficient after aging or do I have some other problem? I read a post that mentioned 're-clockling' the throttle body return spring, but no details on that process... could this be the issue or unlikely? What else might be going on to cause this? Do I just need to pull the TB and fully clean everything?
 

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Discussion Starter · #3 ·
I would thoroughly inspect that throttle body before something dangerous happens. They sure don't need another spring.
Click the link below.

http://cruiser54.com/?p=94
I checked out the link to your site, but I don't believe there is any issue with the idle stop adjustment screw. With the extra spring it returns to the idle stop. Without the extra spring I can manually push the throttle linkage to the stop and get it to idle normal. Seems like must be build-up on the shaft of the butterfly where it pivots in the TB. I was going to pull and clean today but ended up replacing the thermostat housing instead.

Hopefully when I get the chance I'll clean it and that will solve the issue. It seems like the OEM spring on the TB has plenty of turns on it so I assume there is enough force to close the throttle completely.

For now I'm keeping the extra spring on there so it's not revving up at 1500 all the time. Makes shifting jerky...
 

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Discussion Starter · #4 ·
OK, I just started digging into the throttle body and have discovered that after disconnecting the main throttle linkage to the TB, the butterfly valve closes as expected and seems to have plenty of force from the original spring to snap closed. So my problem lies somewhere not in the TB, but I'm at a loss to see what is causing so much resistance... The pivot on the linkage (low down, lower than the intake manifold) seems a little loose, but still don't see what causes the resistance. Disconnected, the linkage seems easy to move back and forth. My best guess is something going on with the throttle cable. Disconnected it also the cable seems to move freely as well. As mentioned in my initial post, there was a zip-tie on the spring of the throttle cable, reducing it's overall travel. It appears some plastic parts may have broken off a while ago and this was a temp fix by the PO.

Can anyone provide a good photo of the throttle cable where the spring on it is, and how it is attached to the mounting bracket off the intake manifold?

I also have Cruise Control, but I don't think that is the cause at this point.
 

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Discussion Starter · #6 ·
Have you disconnected the cruise control cable for the heck of it?
Yes, I did disconnect it. The CC cable doesn't make a difference. It's the throttle cable for certain- something about the spring on it is too stiff. Does the photo below look like a 'normal' OE cable? I'm wondering if it wasn't from a different year/vehicle?
 

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