Question about 1999 Ford Expedition

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How can i find a vacuum leak on my 1999 ford expedition 4.6

My expy idles up and down when sitting idle and the head lights and interior lights dim in and out. Also sometimes i have white smoke coming out of the tail pipe but only in the morning time.

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You may be experiencing a problem with your voltage regulator rather than a vacuum leak
however to locate a vacuum leak that can not be found by
1, listening for hissing
2, checking all vacuum line for wear, cracks, or loose fits
you can get a fuel rated fire extinguisher and have it ready (I have done this more than a hundred times and never needed the extinguisher, but there is no such thing as being to safe, please take caution)
sparingly wet vacuum hoses and connections, intake manifold gasket area, any gasket in any component on the intake, upper and lower, waiting for dampness to dissipate between testing, while observing changes in engine rpm, when you find a leak the engine rpm will immediately change, usually rising but sometimes lowering or stumbling

Posted on Mar 29, 2015

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> idles up and down when sitting idle and the head lights and interior lights dim in and out

Probably not a vacuum leak; this can be caused by an AC (also on 'defrost') cycling and with changing engine loading, it is normal for some variation in engine speed although a defective 'idle air control' will allow a fair change in RPM.

The visible exhaust is likely purging the system from moisture (condensation) and not a sign of trouble.

Posted on Mar 29, 2015

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