Originally Posted by jameslleary
Thanks bro...will check that. is it normal to have in the neighborhood of 10-12 hg
at idle on these?
a healthy engine with correct cam timing, idle speed, ignition timing should be up to 17-18"
it is very common for a mechanic or even experienced TD
owner to install a cam "one tooth off",
which - depending on which way it's off - can kill idle quality and vacuum
so add 'check cam timing' to yur troubleshooting list
it's not too hard to pop the valvecover off to inspect the cam,,,
and a good time to upgrade to 88+ roller cam (and PT lifters),
and 89+ "one-piece gasket" valve cover.
yes something seems hokey there...
power side should stay near 5V even when hooked to sensor...
either sensor is bad (most likely),
or there's a problem in the wiring harness/connectors or (less likely) ECM
I would be interested in whats happening to the 5V supply to e.g. the TPS
if that's dropping too, or not ?