Typical Exhaust Pressure ?

[lanierboy]

My manifold pressure is low and I suspect that my exhaust pressure may be too high. Since I have a projection EFI, I suspect that I can remove the O2 sensor I installed at the Y and hook up a pressure guage. What should my pressure read?

I haven't done this yet but I'm going to stop by the hardware store this weekend of pick up the correct fittings.

[Rogue]

between 3 - 5 lbs at most maybe as high as 7 with cat convertors

some pressure is a good thing - without it the negative pulse waves of the exhuast won't help scavenge the gases out of the cylinder during valve overlap

[carrotman]

Low vacuum is usually caused by vacuum leaks, but a clogged exhaust could also do it. If you want to see if the cat is blocked, you probably have to do a pressure reading before and after the cat and compare readings.

[Buggzz]

Originally posted by lanierboy:
[QB]My manifold pressure is low and I suspect that my exhaust pressure may be too high. Since[QB]The redneck diagnostics, Take the exhaust out of the picture. Diconnect the exhaust before the cat. if the manifold vac increases dramatically, you got a blocked exhaust. If not, you got a LOUD truck.

I would bet on a vacuum leak, but if you have checked it all to no avail, try the exhuast.

[lanierboy]

I like the the redneck diagnostic procedure. It's something I can understand and the only biproduct is extra noise! A win/win :D