Once more into the void...- does someone have a flashlight?

[Joshua van Tol]

I'll second this. The same failure happened to me. On mine, it  
appeared that the spring was broken or weak, because it would only  
*sometimes* idle high. In any case, a good used replacement fixed it.

Diagnosis is easy if you clamp off one of the two hoses going to the  
valve while it's acting up.

On Oct 24, 2006, at 7:11 PM, John Cody Forbes wrote:

> JOHN SHERROW wrote:
>> I don't think the car can "idle" at 3000 rpm.
>>
>> I put idle in quotes because at idle when the TPS is closed the decel
>> valve should kick in if the RPM's are above 1500 rpm. This creates
>> the cycling idle some people complain about when the idle goes awry.
>>
>> I'd say the throttle switch wiring is kaput.
>>
>> Does the idle stay at 3000 with the ISV unplugged? I read awhile back
>> that some one replaed the control module and solved a similar
>> problem. Based on what I've read about the decel valve the solution
>> did not make sense to me.
>>
>>
>
>
> The ISV being all the way open (stuck open) will make it idle at 3,000
> almost exactly. I figured that out on my 5ktq once I cranked the  
> boost a
> bit. When closing the throttle the pre-throttle post-turbo ISV  
> intake blows
> the ISV piston back into the body of the ISV so hard that it  
> destroys the
> ISV. Went through 3 of 'em before I figured out what was going on.
>
> -Cody Forbes
> http://www.5000tq.com
> '86 5k noT noQ
> '86 5k noT noQ - Parting Out
> '87 5ktq
> '87 5ktq - Fast. Really Fast.
>
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