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87 CRX SI Idle Problem

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Old 05-29-2008, 05:35 AM   #1
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Default 87 CRX SI Idle Problem

OK, My 87 SI is now running but I'm having trouble with the idle. As far as I know there are three things that control the idle. The fast idle valve has a large inner screw that usually isn't messed with and a smaller external screw. Additionally there is an adjustment which I call the base idle screw external on the throttle body which is also not usually messed with.

All these settings have been previously messed with, so I'm trying to get back to a good baseline.

Is there a procedure to set all three of these screws up properly without resorting to trial and error. When I screw the internal valve down in the fast idle valve my idle drops and becomes more controllable but there is a noticeable dead spot just off of idle. The engine catches and picks up fine but the dead spot is noticeable.

When I screw the large internal valve up, the idle comes up and the dead spot is reduced (more air past the throttle plate). The problem is that by the time the dead spot is gone I'm idling at 2500 rpm's with the smaller fast idle screw all the way down and the base idle screw all the way backed off. At this point the engine does not want to come down quickly from a high rev, I presume it's getting to much air bypassing the throttle plate.

I can probabaly get pretty close over time to an optimum balance between the three adjustments but it would be nice to know if there is a procedure to balance them out. Furthermore, does anyone know if I'm missing something regarding the dead spot? Is there something else that can cause that to happen. If it wasn't for the dead spot I think it would be pretty easy to find a good balance between the three adjustments.

I have not had a chance yet to check my TPS which could be a problem for the dead spot.

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Old 05-31-2008, 03:18 PM   #2
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Default Re: 87 CRX SI Idle Problem (Acemcguyver)

if you have the original hood look underneath it and it will tell you your range also helps if you mention if its stick or auto
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Old 06-02-2008, 01:39 AM   #3
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Default Re: 87 CRX SI Idle Problem

Check your coolent system, the idle will bounce up and down from air bubbles in the system. Its easy to check and rule out...
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