Spark Advance

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toliphint
Posts: 62
Joined: Sun Aug 08, 2010 6:35 pm
Location: Montgomery, AL

Spark Advance

Post by toliphint »

Ever seen anything like this?

Was logging with TunerPro and noticed in the log file that ‘Spark Adv Rel. to Ref Pulse Degrees’ was reported at 0.35* for the entire log. No codes were set. Later determined that this was happening shortly after engine startup, so did a brief engine start-up and shutdown log. ($8d, ‘7730, TPI with separate-coil HEI distributor).

Have log file but see no way to post it here. In the file, right after engine start, ‘Spark Adv Rel. to Ref Pulse’ goes to a weird set of 5 digit numbers for 3-4 seconds, then briefly to zero and then fixes itself at 0.35*. But ‘Spark Adv Rel. to TDC’ appears correct. Again, no codes when this occurs. It’s also weird and/or coincidental that the difference between some of these sets of 5-digit numbers is 0.35.

Have confirmed multiple times that the ECM SA setting is 8.09* and timing is set at 8* with ESC connector disconnected. Car runs OK, but seems sluggish. No changes have been made to the bin.

Any ideas on what can cause this or what I can look at? Have confirmed that all connectors on distributor and coil are solid, Ditto for ESC connector.

One other thing in the log – Before cranking the engine, a CODE 21 ‘Error’ is shown, but it disappears when engine craning begins. No CEL light and no further codes. I’ve back-probed the 3 TPS wires and all voltages are as they should be. Help Please!
Thanks!
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