September 26, 200421 yr Hi, Still trying to find right RPM"s & gears for best economy on '88 DL wagon with SPFI & 4WD, no tach. In the old days I used a vacuum gage with carbed vehicles. Can this be done with SPFI, and if so, where would I tap in? Thanks, Ray Mac.
September 27, 200421 yr What you want to do can probably be done. since I have not done this myself I couldn't tell ya exactly where to tap from. My best guess would be that if on a carbed engine you tapped from the intake, you would still tap from the intake. If you tapped from a ported source on a carb, well you sould be able to tap from one of the ports on the throttle base of the throttle body.
September 27, 200421 yr Hi,Still trying to find right RPM"s & gears for best economy on '88 DL wagon with SPFI & 4WD, no tach. In the old days I used a vacuum gage with carbed vehicles. Can this be done with SPFI, and if so, where would I tap in? Thanks, Ray Mac. I have a vacuum gauge on my SPFI motor. I tapped into the little bung on the passenger's side of the intake manifold. This spot is also used for one of the solenoid in the thermostat housing area. I get about 22 inches at idle, which is about 800RPM on my car. WOT brings it down to about 2-3 now, but my air cleaner is old, so I'm thinking it might get closer to 0 with a fresh one. In this picture you can see where I tapped in: http://bankruptsoul.org/gallery/displayimage.php?album=5&pos=3 Click on the picture to make it huge. The vacuum line that I am using is the one that is shrouded in the corrugated plastic flex tubing if you look closely.
September 27, 200421 yr its more or less a throttle positon guage for your eyes. the best combo is a vac guage, and a air fuel guage. the air fuel guage, tells you when you go into closed loop, and use the most fuel. anywhere on the manifold, below the throttle plate would work for a spfi, just like a carb model
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