I finally put a boost gauge on the 84. It says I've only been running 2-4 lbs of boost. we adjusted the waste gate and got up to 5 lbs, but started getting some ugly knock. It seems to pull pretty well with the low boost on the gauge. Is my gauge wrong? Is my computer not adjusting the timing?
I'm going to test and tune in Tucson tonight to see what kind of time slips I can gather up.
Do you have any exhaust leaks?
Any vacumm leaks?
Is the puck sealing good?
There must be some reason you are getting such low boost numbers? Is it false knock? Do you have a scan tool or a knock gauge?
How did it do at test N tune?
Test n tune was dismal for the Nat. 1st run was 17.5@ 83mph, new gauge said 2lbs boost, 2nd run adjusted the boost and at 6lbs boost detonation was really bad, 3rd run backed off the boost and unhooked the fuel pressure regulator (blocked off the vacuum line) and again had too much detonation and lifted (but ran a 17.3 @ 65 mph)
Gave up and watched my son run my Suburban in the low 16s all night.
Either my gauge is reading wrong, my car hates boost, or the ecm can't retard fast enough to keep up. I'm going to put a knock gauge and a Fuel pressure gauge on for further diagnostics.
David Greenberg
Hereford,AZ
Definitely check the fuel delivery. If it looks good, check the ignition components - make sure you're getting a good spark. (are you running the original coil?) Are you using a vac/boost guage? It might help you determine if there's a vacuum leak somewhere. If vacuum looks good, you might want to try a different boost guage to verify that yours is giving accurate readings. Let us know how it goes.