Engine Woes

[kubben]

I noticed a new sound my engine started to make. At idle it will run normal than sort of pulseate (if that is a word) and rev up.
It's sort of like normal, rev up, normal, rev up.
Is this normal because of the cold wheather?

 

[Robert]

What year and engine? If it's a '97-'01 SOHC V6 it could be leaking intake manifold o-rings. If that is the problem check out the thread under the General board for Owner Notification Program 00M12. Without more information from you, all you'll get are guesses.

 

[kubben]

1996 XLT 4.0 OHV

 

[Tim K]

Does it only happen when you have the Fan-Defogger-Heater-etc...running? I never paid much attention to the engine sounds (97 OHV V6) until my radio was out for a week...then I noticed everything. If it happens only when the heater/fan/etc is running that is normal. Its just the fan/blower (?) kicking in. If you check under the hood there is a "flywheel" next to the battery by the serpentine belt. While the engine is running with the heater on you will see this wheel "catch" and run for a brief while, then release. Is this the cause of your revving?

If this isn't what you are talking about then I am wasting my time and yours!

 

[JoeC5]

I had that problem with the revs going up and down. It happend on my 93 when I would put the defogger on. What happens is, with fords, the a/c compressor turns on and cycles, what caused my revs to go up and down was that my a/c compressor had no oil in it, also i had no freon in the system either.