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1987 924S High frequency vibration

Engine

Vehicle Information: Model(924/944/968): 924S; Year: 1987; Body Type: Coupe; Total Mileage: 114k;

The car in question is suffering a high frequency vibration and appears to run through out the RPM range. The belt drive is aligned properly and the sprockets are on correctly as well, infact the bottom BS (balance shaft)mark is dead on the mark as this one usually is off just a tad to the right of the tab on 944's. I understand this to be a hard alignment to get perfect but mine is. New ISV (idle stabilization valve) and new vacuum lines. Spring centered clutch and appears ok. New ignition components. Car is lowered apprx 1.5". New AFM (air flow meter)/boot. Now the best I can tell you is to imagine your 944 has a cracked or fractured tub and the crack is vibrating when on the gas but smooth at cruise. This vibration is as if 2 pieces of tin are being vibrated at a very hi speed. Best seat of the pants feel I can give you.Car when cold does shake a bit or lope as it were miss firing but once hot the car smoothes out but the vibe doesn't. Only happens when on the gas. I am stumped! Thanks!

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