Quote:
Originally Posted by Clev
Doesn't needle oscillation indicate compression problems?
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...yes and no, or simply: not always.
...if the oscillation "coincides" with the cylinders, then the answer is probalby yes, there's likely a compression problem. But, then again, it might also be: (a) vacuum gauge diagrapham
sympathetically vibrating, or (b) 3 or 4 cylinder engine at low rpms, so there's a big "gully" in the vacuum level as each cylinder sucks air from the intake manifold...almost like "ripples" in the vacuum. That's why I suggested the restrictor...a first step toward diagnosis of "what's causing" the oscillation.
...if we were talking 6's or V8's I'd agree 100% on "problem" but things get 'interesting' on the smaller engines...especially a 3 cylinder!