UPDATE:
She's running... not with full power, though.
- Items completed since last post:
- New plugs got motor to fire and run
- Once hot in shop, checked timing - dead on at 0 w/ECM bypassed, approx 20 BTDC with ECM engaged
- Performed base idle / IAC adjustment per the TBI tuning sheet posted in this thread
- Checked vacuum - holds steady and solid at 18lbs - drops when throttle hit hard then levels right out again
- Seemed problems were resolved
- Test drive report:
- In sunny 85 degree weather w/45% humidity it took it's time getting up to temperature - 180 t-stat is per Jet Performance specs - it barely gets there on the stock GM gauge
- Once heated up under load, fluffy idle and stumbling under acceleration condition that sent us on this mission reappeared
- Rich-smelling exhaust and rough idle is gone, however - smells like a solid motor running 93 octane should smell
- With new oil pressure sensor installed, oil pressure reads very low at idle - almost to the red on the stock GM gauge - then jumps up and reaches 30-35 psi under power
- No oil in water nor antifreeze in oil
- No smoke from motor or exhaust
- Drove approx 30 miles in varied traffic and conditions
- Only got up to 70 mph briefly, due to heavy local traffic - it's tourist season up heeyah
- Stumbles under acceleration - exhaust note seems "loud" - not the smooth "tuned" note it had after we added the Jet chip last year.
- Cruises along at speed OKAY, if not accelerating
- Struggles to generate enough torque to get the tranny to kick down
- Gas gauge did not budge for a change!
- Basically, we are back to where we started prior to all the repairs - fluffy idle and weak/shaky engine under power - minus the really rough idle, horrible smelling exhaust, and poor fuel economy.
I am now very open to the suggestion that the timing chain is really gone and jumped a tooth...
If it would still run - and I've read arguments that it will not - out-of-sync valve timing would certainly explain most of these problems.
Curious to hear thoughts about the vastly different spark plug conditions - some clean, some oiled up/black, some sooty/brown...
As always, we are very grateful for your input!
THANK YOU!