Holley EFI manual said:
Crank & Cam Sensor Diagnostics
One of the most frustrating problems that can occur with EFI is crank and cam sensor signal issues. In order for an EFI system to operate properly, it must get proper crank and cam sensor signals. If there is a crank or cam signal issue, such as missing or extra pulses, the Holley EFI systems will show this on a datalog. If you feel that you are experiencing a crank or cam sensor problem, take an internal datalog at 100 samples per second of the problem. Add the “Diag #1” parameter to one of the datalog views and review it in the problem area. Look at the “ones” and “tens” positions of the “Diag #1” parameter. Once the engine is running, these positions should NEVER increment [increase]. If they do, it signals a crank or cam sensor signal problem. If you need help diagnosing this, it is recommended that you contact Holley Technical Support.
The crank sensor is the ones position (1st digit left of decimal point), and the cam sensor is the tens position (2nd digit left of decimal point).
FYI: Digital falling is much preferred. I've datalogged the difference on the same Hall-Effect sensor, and digital rising had errors.
NOTE: Momentary RPM Errors while cranking/starting & turning engine off, are acceptable (per Doug_F).
(Image courtesy of bigd427w @
Modern Speed)
If the data log indicates a cam/crank sensor error, I highly suggest you record a "special log" (.SL suffix) and email it to Holley Tech for analysis, so they can inform you if a sensor is malfunctioning and what it's doing wrong. It's a special high speed data log of the cam/crank signals that only Holley Tech can read with their special oscilloscope software.
Doug_F said:
With the EFI, we can do what we call a "special log" or .SL log.
This basically gives an "oscilloscope" type high speed logging of the crank and cam signals.
How to record a .SL datalog:
Click on "File" (top left corner of HEFI software) and "Global Folder Properties".
Erase "Blank Global Config" and type this code in the first line
4827KWYD2946WMNF.
Click "Save" (top left). Then record a
short internal data log, and download it (key-on, "USB Link" mode).
Obviously, you must "Enable Input for Internal ECU Log" ("Basic I/O" in "System Parameters"), and wire a switch in an inconspicuous location. It can be ground activated, so it's a one wire task. Then you can data log instantaneously at any time, without a laptop in the vehicle. A necessity for diagnosing stubborn spots of a tune and/or instant data acquisition.
FYI: After recording the .SL log, remember to erase the aforementioned code in "Global Folder Properties" (click "Save"), so you can record regular internal data logs the next time you need to.
NOTE: You can simultaneously record an internal .SL data log
and a regular PC (laptop) .DL data log, and email them both to Holley Tech. This way, you can review the regular .DL data log to ensure it contains the issue at hand.