Cadillac DeVille 1990 130,000 miles scrupulous maintenance 4.5 L code 3 fuel injected
Engine vibrates; frequency proportional to speed and accelerator depression; coast smooth.
Two episodes. First no trouble light. Resolved spontaneously. GM dealer tuned engine. Smooth. Checked compression one cylinder lo.
Underwent $500 tune up.
Several days later vibration as above this time with trouble light on and dealer verified vibration this time. Passenger can feel vibration.
Dealer could not identify a code. Suspect warning light intermittent. Checked more compressions. Several low.
No antecedent symptoms; no oil usage. No blue exhaust smoke. Pristine outside and interior.
GM dealer says we need new engine.
Hard to believe because sudden onset; it has come and gone and now come back. Interim smooth as silk.
Two perhaps unrelated observations:
Two weeks earlier someone removed gas tank cap. Purchased a new one promptly; could something have been added to tank?
In earlier years trouble light meant a new oxygen sensor was required. Although auto was running smoothly. Light only symptom.
Like the car.
Desperate for advice.
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Thursday, October 1st, 2009 AT 2:50 PM
