Most car/truck engines are 4-stroke engines, this means for one complete cycle each piston goes to TDC two times.
So crank goes around 2 full turns for one complete power cycle of engine.
Cam only goes around 1 time for complete cycle.
So you could simply be on the wrong TDC to setup Cam synchro.
The TDC you want is the at end of compression stroke, so with #1 spark plug out, rotate crank in its "running" direction with finger or compression gauge in the hole, when you feel finger getting pushed out or see pressure building on gauge the next TDC mark line up on crank pulley will be the one you want to setup Cam Synchro and CPS
1. Intake stroke, piston is starting down the cylinder from TDC, cam is opening intake valve, fuel injector will open, air/fuel mix is being sucked in by piston going down the cylinder
2. Compression stroke, piston has reached the bottom of cylinder, intake valve is closed, piston moves up cylinder compressing/heating the air/fuel mix.
3. Power stroke, compression stroke ends as piston travels past TDC and starts down, spark plug ignites air/fuel mix, it expands rapidly pushing piston down, which powers the crank shaft.
4. Exhaust stroke, piston is at the bottom of cylinder after Power stroke, cam opens exhaust valve as piston moves up cylinder which pushes exhaust out of cylinder.
Back at TDC and start of intake stroke
Spark and fuel injector(CPS) timing is all based on Compression stroke TDC.
Last edited by RonD; 12-20-2015 at 01:03 PM.