Hey I wanted to check in because I think I may have solved my issue. I’ve been racking my brain about this whole situation really trying to understand what’s going on with the FPU VSV. I had my AFM off the other night and it tested good, and within factory spec. I read that the coolant temp at which the FPU VSV is activated is approx 210°F, however this could vary between engines (it did not specify the temp for the 22R-E series engine). I went and purchased a Klein IR digital thermometer so I could get an solid idea of what temps are.

I wasn’t hitting 210° on the radiator. I was hitting maybe 180° max. This is good because I just put an OEM style radiator that has 3 cores in it maybe a week ago. There’s something else going on though; I’ve had idle issues with my truck for such a long time. I have a smoke machine and I’ve used it many times with no success trying to find where a possible vac leak may be. I’ve always had to keep my idle adjustment screw completely seated because even if I opened it a tiny bit, I would get idle surging… a vacuum leak. That’s kind of when it hit me: I’ve never replaced the tiny little Oring on the throttle adjustment screw. I’ve removed the screw and saw that the Oring was nice and flexible, so I never paid any mind to that. One thing I didn’t think of was the previous owner. He half-assed SO MUCH on this truck. I think he replaced the Oring at some point but just used whatever was laying around his garage.. an improper sized Oring, that, you may have guessed, was possibly not sealing.

I just got back from the hardware store with a metric sized Oring (7.8id x 1.9 thickness) and so far, things are looking promising. I haven’t driven it much, so I can’t say for sure, but I think this may be the end of my journey. If this is what solves my issue, then I’m no longer going to consider a swap for a newer engine.

Anyway, I didn’t have anyone to share this possible victory with, but thought maybe you’d get a kick out of it. Nearly a year I’ve been fighting this truck, and it pretty much came down to a tiny piece of rubber, that probably costs about 1¢ to make.