93 tbi has a mind of its own.

[Rndiesel]

I spent all day today testing my 93 chevy tbi timing advance.
Basically , it wouldn't come off base timing.
Steady 0.
So after much troubleshooting I replaced the ICM. Now the timing advance comes on.
Except it does it even when its unplugged.
None of the wires are shorted together.
I even cut the advance wire at the ICM.
Should've just tested for a short to power but.. ill solder it later.
Cap is on tight.
Hold down is on tight.
Oh and it will idle really good then rapidly advance / retard the timing , then die

 

[Wes Harden]

Check the knock sensor, over tightening the knock sensor will give false readings and the computer will retard the timing. Knock sensor is in the block by starter. When you say ICM do you mean the module in the distributor?

 

[Rndiesel]

Yes the icm in the distributor.
I thought the advance wire has to be hooked up for the computer to change timing.
Isnt that the whole purpose?