- Joined
- Mar 10, 2005
- Location
- Hooterville (24171)
OK TBI gurus, I need some help! The TBI system is in place and fired right off the bat. Starts with just a twist of the key, runs high idle (1100) until 190*F, then drops to 600rpm. The 350 bin'd chip was MEGA rich (will post a pic of the DDs bumper = black) has been swapped for a 305 bin'd chip (much leaner, but fuel tables still need work later).
The DuraSpark dizzy feeding the EST was NOT pulled or moved (just disabled vac & mechanical advance) and left it at 5*-7*BTDC (where it ran on the carb) due to AMC folks telling me 5*-10* base/initial was where they were happier at than 0* like the Chevys. Running ALL GM modules (MAP, EST, ESC), sensors (CTS, Knock), & GMs TFI coil. Plugs are at .040" & wires were fine on the carb w/ no "leaks" seen at night). First test drives felt very low on power and big hesitation going to WOT under load. Timing light showed 15*-17* at idle, so I spun the dizzy to about 20* BTDC. Power and hesitation where better, but still not good compared to carb.
The problem appears to be NO timing advance. Regardless of rpm... 600, 2K, or 3.5K, the timing light shows approx. 20* BTDC with a small 2*-3* fluctuation during accel. Approximate because there aren't any marks in that range, so I lined up the balancer mark on TDC & used a Sharpie to mark 10* increments forward to 30*.
I've tried pulling the timing/EST bypass to set the base timing, but it won't start with the bypass unplugged and when it *IS* running and the bypass disconnected, it immediately shuts off!
The EST has been tested multiple times (OTC tester @ O'Reilly's x2 & Wells tester @ AZ x 2) and ALL EST voltages (Pin B/D5 4.75V & Pin D/D4 1V) are good, as well as the key on voltages for the rest of the system. EGR function is "disabled" (set to 200*F). No codes have been thrown, only 12...
Any ideas? Seems 20* static may indicate it's still running on the limp home chips, even though WinALDL shows it's goes into closed loop on the road (rich flag is set repeatedly too)...
I'm happy to answer any questions
The DuraSpark dizzy feeding the EST was NOT pulled or moved (just disabled vac & mechanical advance) and left it at 5*-7*BTDC (where it ran on the carb) due to AMC folks telling me 5*-10* base/initial was where they were happier at than 0* like the Chevys. Running ALL GM modules (MAP, EST, ESC), sensors (CTS, Knock), & GMs TFI coil. Plugs are at .040" & wires were fine on the carb w/ no "leaks" seen at night). First test drives felt very low on power and big hesitation going to WOT under load. Timing light showed 15*-17* at idle, so I spun the dizzy to about 20* BTDC. Power and hesitation where better, but still not good compared to carb.
The problem appears to be NO timing advance. Regardless of rpm... 600, 2K, or 3.5K, the timing light shows approx. 20* BTDC with a small 2*-3* fluctuation during accel. Approximate because there aren't any marks in that range, so I lined up the balancer mark on TDC & used a Sharpie to mark 10* increments forward to 30*.
I've tried pulling the timing/EST bypass to set the base timing, but it won't start with the bypass unplugged and when it *IS* running and the bypass disconnected, it immediately shuts off!
The EST has been tested multiple times (OTC tester @ O'Reilly's x2 & Wells tester @ AZ x 2) and ALL EST voltages (Pin B/D5 4.75V & Pin D/D4 1V) are good, as well as the key on voltages for the rest of the system. EGR function is "disabled" (set to 200*F). No codes have been thrown, only 12...
Any ideas? Seems 20* static may indicate it's still running on the limp home chips, even though WinALDL shows it's goes into closed loop on the road (rich flag is set repeatedly too)...
I'm happy to answer any questions