Jump to content
Ultimate Subaru Message Board
Sign in to follow this  
Guest Legacy777

Throttle Body.....high idle fixed.....mostly

Recommended Posts

Guest Legacy777

Well.....I got a throttle body from a buddy. It was off of turbo legacy. Don't know the vintage or such.


Well it has the black goo or sealant around the throttle plate to help seal things.


BUT.....I found something else.....very interesting. On the 90 legacy the throttle body has an adjustment or air bypass needle valve to let air around the throttle plate.


The new one did not have this. I had no idea that screw even did anything......when looking at it before. After getting the new TB I noticed the difference. Plus the support for the plastic cover hid the screw.


I played with the screw, and adjusted it. I could get the idle down, but when starting up it still revved higher then it should when warm....and just didn't seem right.


So I swapped the TB's, idle is good now.....even without the little adjustment screw. The idle may be a little low. I'm not sure. I need to get an external tachometer and if it is low, I will turn the IAC valve slightly so that it is around 700 rpm.


Only prob with things now........at full throttle and high rpms there is a whistle, which sounds like a vacuum leak. It only does it at high rpms. I can't find the leak. I don't think I put the gasket on improperly. Unless the TB I got is not sealing properly around the throttle plate shaft.


If I can get the idle set/IAC adjusted and this stupid whistle gone........I can stop messin with this and move onto other things.......jeez...


Oh....here's some pics of the new TB and the one that was on there.









Anyone got any idea about the squealling at high rpms?

Share this post

Link to post
Share on other sites
Guest Grounded1

Hey Josh

Those are some really good pictures. Most of the adjustments on the TB aren't even addressed in the factory manuals. Do you put the gasket in dry? Sometimes a light coat of petroleum (vaseline) and then wiping the excess off so its just moist helps gaskets take a good set when bolted down. Did you check the idle rpm with another tach. I'm beginning to question the accuracy of my tach below 1000. If I read mine right it idles at about 600-650. I just found my speedometer was off by 3 to 4 mph slow. And I'm running stock wheels and tire sizes. So the tach could be off as well.

By the way,What was the stuff you used to clean out the engine right before you got this problem?



Share this post

Link to post
Share on other sites
Guest Legacy777

I put it in dry. I suppose I could try the vaseline trick. I have not checked the RPM with the tach yet.....been out of town......plus I gotta get a decent one.....found one today....but it doesn't have an inductive pickup.


I'm hoping on doing that first thing in the morning. I have been wondering if there is some tiny amount of air getting by the IAC valve at high rpm because it's set just a tad too low. I'll let ya know what I find out.


A lot of **** been goin on today.....get back from the airport tire is flat....have to put spare on......and go through the hoops to get it fixed......just not what I wanted to come back to........


Oh and I used this stuff to clean the TB www.carfood.net/trimthrotbod.html


any carb/TB cleaner will probably result in same problems.....

Speedo is almost always off a little, even with stock wheels and tires.......guess the factory just does it.....who knows.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this