Hot/cold idle speed reversal

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MrTow
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Hot/cold idle speed reversal

Post by MrTow »

This is quite a long-standing problem that I've finally tried to fix while I've had some time over the last couple of weeks. The idle is around 1200rpm when warm and low (about 850rpm) when cold. Seems to basically be the reverse of what it's supposed to do.

I've cleaned the idle speed control valve thinking that might solve it. I also checked the resistances over the ISCV terminals (fine) and it flicks open and closed when you apply voltages across the terminals as in the Toyota manual. The only thing I'm a bit unsure about is that the little valve doesn't ever seem to be fully closed, which seems a bit strange.

Has anyone else had any similar problems? Car is a rev2 N/A.



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abovetherim
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Re: Hot/cold idle speed reversal

Post by abovetherim »

Sounds like a vacuum leak to me
1991 rev 1 T Bar n/a 3sge import. A work in progress!!!

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MrTow
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Location: Sunny Manchester

Re: Hot/cold idle speed reversal

Post by MrTow »

Thannks. Hadn't thought of that. Are many things controlled by vacuum on a 3s-ge? I've seen the pipe to the T-VIS but don't remember seeing any others.

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abovetherim
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Re: Hot/cold idle speed reversal

Post by abovetherim »

If you look under the intake manifold from under the car there are quite a few vac lines and gubbins.
Vac leaks can also occur at TB to manifold gasket, idle air valve or intake gaskets.
1991 rev 1 T Bar n/a 3sge import. A work in progress!!!

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