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APorsche914
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I NEED HELP!!

my '72 1.7L is running now, but it idles at 3000rpm, i can put my hand over the air intake, has no effect, turn the idle screw, no effect, turn the disttributor till it drops to 1200rpm, but its so off time it has no throttle responce, and what hose would have that big of a vacumn leak that having no air from the throttle body would still leave it at 3000rpm, i cant figure it out, ive tried so many things, i need any advice or info you willing to offer! thanx
Old 11-14-1998, 08:13 AM
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If it is a vac leak, you should be able to hear it really easy. I can hear the air in the idle circuit of Julia's 1974, but I have my head at the engine compartment and cover the ear pointing outwards. You could try the "spray some carb cleaner till it stumbles" idea and that should show if it is a vac leak. Is the advance mechanism in the distributor working okay? If stuck at full advance it will not run right. Hoses can get a split, and if it is on the bottom of the hose you can't see it, especially if they are not the fabric coated kind. Our 1974 actually had a hole in the plenum under and just behind where the throttle body bolted on, so anything is possible.
Old 11-14-1998, 04:55 PM
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It *has* to be a vaccuum leak. The engine will not run if there is *no* air getting in. So, if it still runs when you cover the air intake, air is obviously getting in from somewhere.

Does the engine still run if you take the air cleaner (etc.) off and cover the throttle body itself? If so, you definitely have a leak.

All the hoses are possible sources. Check for cracks in the manifold. Check the seal between the throttle body and the manifold. Not sure what that seal is like on 1.7s, though. Check the "manifold boots", the big hoses that go from the manifold to the intake runners. Check the inner fuel injector "donut" seals. Check the seals between the intake runners and the heads. Use some vise-grips to close off the large hose from the manifold to the decel valve.

Just keep checking all the places where air could be leaking into the intake system.

--DD
Old 11-16-1998, 09:50 AM
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Sorry Dave for the confusion, but I thought he was talking about the air cleaner? I have seen the filter element get crushed on one side so the air wasn't going in the regular inlet. As Dave said, if it continues to run with the air cleaner off and your hand over the throttle body it is a vac leak. Some other places to look would be the intake gaskets as they can cause leaks (911s too). The starting injector seals along with the regular injectors could cause it too. I don't know if the 1972s have the molded fitting that the crankcase vents into that fits directly to the intake plennum like ours but it could be cracked like our was since it was 24 years old. Good luck and I hope you post what the fix was....
Old 11-16-1998, 12:59 PM
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