Got her running..., 4000 RPM idle speed!!!! Options

[bpetry]

OK, so I just got my '72 1.7 EFI running for the first time. Replaced all the vacuum and fuel lines and I thought everything was hooked up corectly per the pelican tech diagrams but after she fires up she idles for a few seconds and then zips right up to 4000 RPM (with no muffler I'm sure the neighbors loved that!). The throttle plate is almost all the way closed so it must be sucking air from somewhere else. I pinched off the big hose that goes from the plenum up near the oil fill and that seemed to slow it down a little, but I don't like letting it rev that high, especially when it hasn't been run in so long so I shut her off and figured I'd come in and ask the experts, any ideas?

Regards,
Brian Petry,
Springboro, OH

[nola914]

There's a bunch of possibilities. Sounds like too much air Re-check all of your hoses and connections for leaks. I use clamps on EVERYTHING, and I test all of the hoses for leaks from cracks with the old "mouth pressure" test.

The throttle plate should be completely closed, and the air intake controlled by other mechanisms.

Throttle Switch. Check for 22 clicks as the plate opens and check if the open and closed contacts are working. Also check the idle speed adjustment on the switch.

Aux Air Valve not closing properly, or the hose is leaking.

Fuel Pressure. Too much will make it run very rich. Shd be 29.5 psi.

The idle air by pass screw. Maybe open too far.

Manifold Pressure Sensor. Could be defective. Also check that the hose is not leaking.

Personally, I wouldn't change the ECU knob settings until all else has been checked.