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Idle Adjustment Screw '98

Old 01-29-2011, 03:14 PM
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Oz-ATL
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Default Idle Adjustment Screw '98

Where is this located on the throttle body?

I'm having a touch time seeing it behind the SC and IC.

Any reference pics would be great.
Old 01-29-2011, 03:21 PM
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x50type
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I understand it's quite difficult to find.
Old 01-29-2011, 03:55 PM
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BobbyT
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I didn't know the 993 had one. Isn't the idle speed controlled by the Idle Stabilizer Valve and the engine management system?
Old 01-29-2011, 04:21 PM
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Crimson Nape Racing
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the idle is adjustable but not with a screw like the older cars. you need to remove the epoxy covering the 3 small screws on the ISV and partially disassemble it. The idle is adjusted by rotating the body of the ISV while it is loose (IIRC). There are instructions somewhere on this site (I have a hard copy in my notebook), but it is not intuitively obvious, so I would not try it w/o them. Search for idle adjustment or light weight flywheel stalling. If you cannot find it, I can scan my copy and send it to you.

I had to raise my idle slightly when I put the LWF in, but I thought the OBDII cars adjusted themselves for whatever mods you make, so you should not need to mess with yours.
Old 01-29-2011, 06:55 PM
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Oz-ATL
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Originally Posted by Crimson Nape Racing
the idle is adjustable but not with a screw like the older cars. you need to remove the epoxy covering the 3 small screws on the ISV and partially disassemble it. The idle is adjusted by rotating the body of the ISV while it is loose (IIRC). There are instructions somewhere on this site (I have a hard copy in my notebook), but it is not intuitively obvious, so I would not try it w/o them. Search for idle adjustment or light weight flywheel stalling. If you cannot find it, I can scan my copy and send it to you.

I had to raise my idle slightly when I put the LWF in, but I thought the OBDII cars adjusted themselves for whatever mods you make, so you should not need to mess with yours.
I read that old post but Todd from Protomotive hinted at another way to adjust it, he may have been thinking about another vehice year.

I would love any links or docs, it's causing me to not want to drive the car now. cozment@innercon.com
Old 01-29-2011, 07:24 PM
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Going to clean the ISV before I change anything. If that doesn't work, I'll adjust the connector counter clockwise.
Old 01-30-2011, 05:01 PM
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Cleaned the ISV and yes it was very dirty with sut buildup. it's amazing how it feels when you take it off vs. after you clean it. I didn't see any movement in my valve at all!

Seems to be running very smooth now and not as prone to stall although it does still stall especially engaging the clutch coming into a turn.

I'm going to drive it for a few days to see if it improves before I tackle the connector adjustment. By connector I assume it's the electrical connection to the ISV?


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