High idle after engine warms up...
 

Hi,
I run into a small problem that really bugs the h*** out of me.

After the engine warms up, AND you drive it for a while. After I remove my feet from the accelerator (say stop at a light), the idle will most of the time go from the normal ~850 to around 1300rpm.

It might stay there for a long while then drops back, or sometimes it will just stay there.

I though it might be a sticky throttle linkage, but it seems to return to normal position everytime.

Any thoughts?

thanks...

below the intercooler is a deceleration valve. the large round gold thing. remove the small hose from the middle of it and plug the hose. then see if it makes a difference.

John, my car does the same thing. Can you permanently bypass this valve?

Yes you can get rid of the decel valve if you want.

What is the effect after elemination of the decel valve?
What function does it serve in the stock application that is not needed by the enthusiast?

I think the decel valve was put on for emissions. With the valve removed you idle will go down to normal much faster. Like a car should.

Is this decell-valve???

Yes, that's it.

Mine is history. We'll see how she runs without it.

Guys, I take it this is the same or similar setup on an NA 3.2? Mine suffers similar symptoms.

JW et al,

I recently unplugged the decel valve on my 80SC. I notice a bit of popping on decleration, I assume this is now considered normal? Also, some folks refer to *smashing* the decel valve a few mm to cure the high idle problem. Is there an actual procedure to do this?

TIA

-Brad
80SC

Allright this was really interesting!

If I want to unplug the decel valve should I just plug the tubes or should these be connect together so the flow passes by?

/J

If you want to take the decel valve out you should plug the openings, not connect them together.

OK! Thanks!

But the smaller tube "on the decel valve"must be plugged?, have I understand it right then?

/Jocke

Is it enough just to disconnect the middle-hose on the picture and plug it w/o removing whole valve and plugging two hoses behind?

Unless your valve is blown. Then you have to take out the unit and plug the ports. I would take the whole thing out anyway. It cleans up the engine compartment and saves about 1/2 lbs. Woo-hoo

Hmmm... :) I heard stories of flames belching out on high-rpm lift-off when deccel-valve is plugged...

True?

I wish I had flames. It doesn't happen on my car. The only thing that I notice is that the idle returns like it should and the exhaust burbles alot.