High Idle

[DSPTurtle]

What would be causing my 74 1.8L from dropping back to idle? It seems to want to hold somewhere between 1,200 and 2,000 depending on where I push in the clutch to disengage the tranny. I can "drag" the idle down by slowly letting up on the clutch and it will hold the lower idle until I accelerate and slow down again.
Any advice???

[bowlsby]

Look for vacuum leaks, an open aux air valve or decel valve. Check injector seals, throttle body gasket and all vacuum hoses.

[DSPTurtle]

Could it be the Decel Valve? The car basically sat in a garage for the last 14 years. It is slow going but at least now I can drive it to and from the parts store
Thanks in advance!!!

[Bleyseng]

or a leaking oil filler cap gasket.
Geoff

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76 914 2.0L

[Dave at Pelican Parts]

Vacc leaks on an L-jet car will often result in a car that idles very poorly, rather than one that idles too high. A malfunctioning Decel Valve might cause the symptoms you're describing.

The ignition timing could also give you these kinds of symptoms as well. Make sure the hoses are hooked up correctly (i.e., if you only have one vacuum fitting on the throttle body it goes to the retard fitting pointing back toward the distributor body, and the advance fitting does not get connected to anything). Make sure the diaphragm in the vacuum dashpot is not broken. Make sure that the points plate moves smoothly when you apply a vacuum to the retard fitting. And make sure that the points plate moves reasonably smoothly by hand as well.

--DD

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Pelican Parts 914 Tech Support

A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling

[mejulihn]

Sounds like a tempermental decel valve to me.

[TimW]

“…depending on where I push in the clutch…”

Clutch plate drag, or might the clutch and accl. cables be binding up?