Would appreciate the brain trust weighing in on this. In going thorough the $8D code reviewing the start-up logic, have been trying to understand the difference between Distributor Reference Pulses (DRP) and Time Between DRPs (TBDRP). Have searched forums and posts and have read until my head hurts. The result is a lot of conflicting information.

So would like to start with this (‘7730, $8D, V8, TPI, External coil HEI):
  • How many DRPs per crankshaft revolution?
  • How are DRPs calculated?
  • How is TBDRP calculated?
  • TBDRP seems to be referred to as the “Reference Period”. Is that correct? What does that really mean?
  • How do both DRP and TBDRP relate to Injector Base Pulse Width (BPW), if at all?


Part of my confusion comes from how a $8D ADX file converts some raw data. It uses the same Conversion Factor of 15.26 (assume this is uSec per DRP???) for reporting both TBDRP and Injector BPW.

Just some of many questions. Would really like to understand this so let’s start a discussion.