1991 Ford Thunderbird Logo
Posted on Oct 05, 2010
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1991 Ford Thunderbird with a 3.8 V6 Started out running rough cold, like it was missing. Tuned it up, cleaned the injectors and throttle body. Running got more rough and at low idle. Found intake manifold leaking. Replaced gasket and now it runs ROUGHER and all the time. Shakes pretty harshly at low rpms, smoothes out at highway speeds. However it has plenty of power and is getting good gas mileage. Checked the compression in the cylinders three times now and all are between 120 and 135. Any thoughts as to the problem?

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  • Posted on Oct 05, 2010
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I think your car has a 7th injector called a cold start injector. Takes the place of a choke. If it does check n make sure it's working properly. That's all I can think of at this time. Hope it helps. Also sounds like you still have a pretty bad vacuum leak. Listen for hiss at idle. Good luck

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