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914World.com _ 914World Garage _ how does a Deceleration valve fail?

Posted by: brant Sep 26 2004, 12:05 AM

I'm suspecting my decel valve may be not working or intermittent?
do they partially fail

I've checked the AAR, and all the hoses for vacuum leak
I've got low idle at start up but after it hits operating temp its fine...
(AAR is working correctly)

I'm wondering how the decel valve works.
Is there a diaphram or something in there to fail?
Is there a way to test it?
how do I take it out and plumb around it?

brant

Posted by: Bleyseng Sep 26 2004, 09:02 AM

plumb around it.

If you have a low idle at start up the AAR valve is not working correctly. You should be idling at 1500-1800 at startup and over a 5-8 minutes of driving idle down to 950 rpms.
Remember to set the timing correctly.
Set the idle only when the engine is hot!
Squirt PB Blaster into the AAR valve to lube it or free it up as its does rust and stick.

Geoff

Posted by: brant Sep 26 2004, 11:30 AM

I tested the AAR while car cold and it was open.
I re test while car is warm and its closed.
I even took it out and did a full 2nd round of tests with the freezer..
It passed all tests... I don't think its the AAR, of course I've been wrong on stuff before.

The second thing I did was get rid of the AAR boot, and using new lines re-plumb the vacuum.. I think I've got the AAR nailed.

My symptoms:
When cold, car starts and idles high (1500) or so.
then after 1minute idle drops to 300
Then after 10 minutes of driving Idle is back to whatever I have it set at (1100)

during the 300rpm period it seem unaffected by the idle screw.

I was wondering if the DECEL valve could be causing a lower idle by pulling it down more when cold, and then after it has warmed up to ambiend it doesn't do as good of a job of pulling it down or something...?

how does a decel valve work, does it have a diaphram
how does a decel valve fail.
how do I plump around it (put which hoses where, or just plug them all 3)

thanks geoff

b

Posted by: 2-OH! Sep 27 2004, 01:21 PM

Brant:

I don't think the Decel valve will solve your problems...

But...

I took mine off and it runs just fine...Just plug the vacuum sources when you remove the hoses...

2-OH!