Thanks, I found it. Kind of a pisser to get to. Now I have to come up with a fitting to screw onto it. Yeah, it is standard "tire stem" Schraeder, but I only have one screw-on chuck and it won't depress the valve stem enough to open it. This chuck is made to be tightened with a wrench, and I think the gasket in it can't be compressed for the stem depressor to work. Maybe I can get a wrench in there tomorrow to tighten it, but it is way too cold to continue tonight (down to 52F now).
Fuel pressure is about 39 psig, with no vacuum to FPR; dropping down to about 30 psig when the engine is idling (and idle vac applied to FPR). That seems kind of low to me, I m used to seeing 44 psig (3 bar) as the lowest for all EFI but the old GM "quadrajet"-like TBI. What is the spec for FP on this engine? We drove around with the gauge attached, the FP seemed stable.
My son thought he heard a hiss from the intake area, but I used a stethescope to listen all around and found nothing.
When driving around, the LTFTs both hit 14.8 pretty often. STFTs moved around a lot, even went slightly negative at times, but tended to be in the 25-32 range. Yeah, it seems like it is running lean!
TPS goes from 20% to about 95%, never any lower than 20% even right after KO no crank/start. That seems bogus to me. Can anybody confirm that Ford considers closed-throttle to be 20%?
MAF also looks odd to me. At idle (700 rpm) MAF is under 0.5 #/min; my calculations are that this 4.2L engine should draw about 1.3 #/min at idle. Anybody know good "real world" numbers for MAF on this engine?
OK, 4.2 g/s = 252 g/min = .555 #/min; pretty much what I m seeing in live-data. Agreed, I'll turn my attention elsewhere. Besides, we inspected the MAF; no grid in this one to get crudded up, just two precision resistors and they looked very clean.
My understanding is that KOEO FP should be 28-45 psig. That is, 36.5 psig +/- 23% This beast, at 39 psig meets that fine, and such a wide tolerance on FP means there is little to look for regarding how well it is being regulated. A drive with gauge attached showed no drop-out of FP, even though the codes got reset. I'm not saying it can't be FP, just that I can't do much more to check it without installing a transducer an logging data.
How about vacuum leaks? I have read elsewhere that these engines seem prone/sensitive to vac leaks at the manifold. I can't hear anything, and am reluctant to flood that area with propane or some other fuel to see if engine sound or STFT changes. What else could I try, smoke test maybe?
Can I rule out EGR, does that ever cause too much O2 (lean) without a misfire being detected?