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Tom Wesenberg · 05-20-2014, 10:11 PM

The 4 cylinder will have an even flicker of the needle due to a suction every half turn of the crankshaft. As long as the flickers are evenly spaced your valves are probably OK. How does the needle read when you have the engine at fast idle, like 1200 or so RPM?

OK, I see you said it was present at all RPM's. Try shorting the plugs to ground and see if any cylinder has little to no effect.

05-20-2014, 10:11 PM	#2
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: vacuum gauge as diagnostics tool The 4 cylinder will have an even flicker of the needle due to a suction every half turn of the crankshaft. As long as the flickers are evenly spaced your valves are probably OK. How does the needle read when you have the engine at fast idle, like 1200 or so RPM? OK, I see you said it was present at all RPM's. Try shorting the plugs to ground and see if any cylinder has little to no effect.