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Cancel advance with shunt

mpt

mpt

Contributing Member
During engine tuning, when I plug in the shunt wire, my 1996 4.3 GS V6 doesn't change in RPM's like it use to! Could it be a bad module on the distributer? Bad coil?
 
Thread title...... Cancel advance with shunt.

mpt said:
During engine tuning, when I plug in the shunt wire, my 1996 4.3 GS V6 doesn't change in RPM like it use to! Could it be a bad module on the distributor? Bad coil?
Click to expand...

The EST (electronic spark timing) system works a bit differently than how average Joe thinks it does.

There is no mechanical advancing system within the distributor.
The driven gear, shaft, triggering device and the rotor remain index-locked with each other.

The system delivers the equivalent of full advance to the module.
The module (via engine RPM) then creates a spark event delay.
The delay is then altered or adjusted as per engine demands/RPM.
(i.e., greater delay at low RPM...... less delay at higher RPM)

When the system is put into BASE advance mode (via the shunt), it goes into full delay.
This is when BASE advance is set/adjusted.
The module then takes over and gives the engine the correct Progressive and Total advance.


All that said.... I am not sure just what could be wrong with your system.


You should be able to find your OEM advance curve for the 1996 4.3 GS V6.
Perhaps strobe your timing marks and see if your EST system is offering the correct Progressive and Total advance.


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After bench testing my coil with voltage tester, I came with 7.7 ohms on the high end (that's subtracting calibration of .12), and low end of .56 ohms (that's subtracting calibration of .12). Are these results within spec?
 
The volvo literature I have specs the primary at 0.35 to 0.45 ohms and the secondary at 7500-9000 ohms, for the est ignition coil
 
jeffnick said:
So, is the advance curve with the EST similar to the stock distributor with the weights?
Click to expand...

The OP's 1996 4.3L stock (oem) ignition is an EST system.

If you are asking about an EST curve -vs- a curve for a mechanical flyweight system....... either should deliver a very similar Total Advance (per RPM). The mechanical curve is typically more linear.


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