Thread: Warming Up
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lucittm lucittm is offline
Manassas, VA
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Join Date: Apr 2007
Posts: 1,211
The smoke test is a valuable toubleshooting tool for our cars. There are probably 100 potential leaks in the intake system. Not so many more than other cars, but a leak there has a dramatic effect on Porsches.

The tech will block the throttle plate wide open and seal off the intake at the air filter except for a small fitting. Using the fitting, he will use a "smoke machine" to pressurize the intake system with 1-2 psi of the same kind of smoke used in hollywood movies; it is made from mineral oil. The leaks where the smoke comes out will be obvious and usually require tightening a fitting or replacing a vacuum hose. Sometimes a hose has popped off, it's just not very plain to our eyes.

The sputtering is classic misfiring and could be one or two bad plugs (cheap) or a bad injector (expensive). I would try the plugs first. You could have fouled one upon start-up after sitting that long. It would be good to know what kind of plugs you have anyway. Since you don't drive it too much, maybe a plug in a warmer heat range would help.

There is a well-documented injector test on this forum, just seach "injector flow test". Did you add new gas after the car was sitting? Bad gas (water) is always a source of misfiring or not running at all.

Also, include some pictures, especially of the engine. It will help folks to visualize your issues.

Good Luck,
1991 964 Polar Silver Metallic Turbo Coupe
Old 02-03-2009, 03:36 AM
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