I have had to repair the IMRC (Behind the alternator) on my 98 winnie. Everything I read on this forum about the actuactor opening at 2900 RPM is what I have the question about. I know in the haynes manual this is what it says also. But....in the Ford factory service manual it says 1500 RPM is when the vaccum cuts off and they open. I have actually watched mine in operation the same time I am watching a Tach and sure enough mine open at 1400 RPM (close enough to 1500). I also got to thinking and I was wondering when the last time was I ran the engine up to 2900 RPM and the answer is very seldom or never......I know at 70 MPH the engine runs about 2100 RPM so this means they would never open for me. So I know 1500 RPM to be the point where they open on the 98' 3.8 L.....is it true with the rest of them.....all we can do is watch them to find out if this is true. Enquiring minds want to know........
