When does the DRP occur?

As I understand when DRP occurs the ECM will fire the injectors right?

When you normally install a dizzy you point NO1 to Cyl NO1. What happens if you turn the rotor so No1 Wire points to No2 cyl, will this affect the AFR readings due to the injectors will fire too soon or too late?

Chasing a AFR error.......

/N.

 

Interesting question. The DRP occurs at the same time the timing light flashes when the EST connector is open. As having the distributor timed at 6 degees BTDC, or whatever it is set to.

The injectors are fired once every engine revolution (sometimes every other, but we will stay with once per revolution). The ECM does this by counting DRPs. And, it does not know which cylinder the DRP came from.

So the actual batch firing of injectors can occur on any cylinder. It all depends upon which cylinder is the first to be counted. For the firing order 1 8 4 3 6 5 7 2, if #1 is where the injectors end up firing, they will also fire on #6, four DRPs later.

If #4 is where the injectors started off, they would fire again on #7, four DRPs later.

When the engine is shut off, the ECM has no knowledge of what cylinder is at TDC firing stroke. Then when the engine is cranked and is now running, the ECM has no knowledge of which cylinder it started with.

RBob.

 

Damn, I though I had come up with something that could be the cause for my problem....

Well thanks for the great explanation RBob!

/N.