Ignition Timing Advance/Retard working reverse

[ScottyWalker7]

Hi all,

I have set up TDC using a strobe and DTI to ensure the piston is at real TDC (the engine fires perfect at TDC using a Tooth #1 angle of 83 degrees). The VR sensor is located 83 degrees before TDC in the direction of rotation on the crankshaft (clockwise).

I'm using Megasquirt II extra so i've set up using toothed wheel (36-1) on 4 cylinder four stroke engine.

In my ignition advance table I can't add more than +90 degrees or less than -10 degrees.

When i increase ignition advance (positive numbers in the ignition advance table), the software seems to add the advance to the Tooth #1 angle of 83 degrees creating an ATDC condition as opposed to BTDC.

I'm either mis-understanding the set-up instructions or have something reversed. I don't know which?

Any advice you can provide shedding light on the situation would be greatly appreciated.

[billr]

[Dennis_Zx7r]

Ignition at 0° means you're firing at TDC. So to fire for example 40° BTDC, enter 40°, not 83+40 = 123°.
Tooth angle is already respected, as you enter it seperately.