holley efi crank-cam setup and diagnostics

Holley EFICrank/Cam Setup

and Diagnostics

As of 2011-08-17

Basics of Crank/Cam Inputs

• Main Preconfigured Ignition Types– Inductive coil (ECU does not control ignition)– CD box out or 12V square wave (ECU does not control

ignition)– GM HEI– Ford TFI– GM LSx 58 tooth– GM LSx 24 tooth– First-gen Northstar– Holley DIS 60-2 with Hall effect cam sync– Holley DIS 60-2 without cam sync

Inductive Coil Input

• Dedicated input at J1A01• Do NOT connect any part of coil to J1A30 or Pin A on

ignition connector• Do NOT connect to any output of a CD box• ECU is triggered when low side of coil >100V• This happens when the field collapses at the end of “dwell”• The ECU cannot control the ignition system- it reacts to a

standalone ignition system• Speed glitches of 133% can indicate extra pulses, 80% can

indicate missing pulses

CD box out or 12V square wave

• Do NOT connect to the coil output of a CD box• ECU is triggered on the rising edge at ~2.3V • An internal pullup to battery voltage is activated• The ECU cannot control the ignition system- it

reacts to a standalone ignition system• End of injection corresponds to the rising edge• Speed glitches of 133% can indicate extra

pulses, 80% can indicate missing pulses

GM “Small Cap” HEI• ECU utilizes stock module for signal conditioning of magnetic pickup in

distributor and switching coil primary current• ECU is triggered on the falling edge of the module’s REF signal at ~2.3V • No internal pullup is activated for the crank/REF• The BYPASS signal is generated by the ECU (by the switchable pullup on

the cam “input”) to assert control of the timing. When low (or open) the module controls timing and dwell. When high the ECU controls timing.

• The EST signal is generated by the ECU to control timing and dwell. Dwell is active when EST is high, and spark happens when EST signal falls.

• Baseline dwell is ~3.5ms, but will be reduced to keep non-dwell >0.5ms at high speeds.

• Speed glitches of 133% can indicate extra pulses, 80% can indicate missing pulses

Ford TFI• ECU utilizes stock module for signal conditioning of Hall pickup in

distributor and switching coil primary current• ECU is triggered on the rising edge of the module’s PIP signal at ~2.3V • An internal pullup is activated for the crank/PIP• The module controls timing and dwell for both start and run• The SPOUT signal is generated by the ECU to control timing and dwell.

Dwell is active when SPOUT is low, and spark happens when SPOUT signal rises.

• Baseline dwell is ~3.5ms, but will be reduced to keep non-dwell >0.5ms at high speeds.

• One vane of the target in the distributor is shorter than the others, which allows the ECU to sync without a cam sensor

• If the ECU cannot resolve the narrow pulse, the tens digit of the “Diag#1” variable will increment

GM LSx 58 Tooth• Crank input reacts to the falling edge of the crank sensor’s signal at ~2.3V• Cam input decodes both edges of the cam sensor’s signal when crossing

~2.3V• An internal pullup is activated for the crank and the cam• The ECU decodes the 60-2 crank pattern and the 4x cam pattern. The 4x

cam pattern should be within 90 crank degrees from the stock location for proper decoding

• Eight individual EST signals are generated by the ECU to control timing and dwell. Dwell is active when EST is high, and spark happens when EST signal falls.

• If the cam signal drops out, falls out of proper phase, or cannot be decoded (not a 4x pattern) the Diag#1 tens digit will increment

• If the crank signal drops out the Diag#1 hundreds digit will increment• Extra or missing crank pulses will increment the Diag#1 tens digit

GM LSx 58 Tooth

GM LSx 24 Tooth• Crank input decodes both edges of the crank sensor’s signal when crossing ~2.3V• Cam input reacts to the falling edge of the cam sensor’s signal at ~2.3V• An internal pullup is activated for the crank and the cam• The falling edge for the cam must happen between approximately 250 crank deg

before #1FTDC and 90 degrees after #1FTDC. There can be multiple falling edges in this window, but none outside.

• Eight individual EST signals are generated by the ECU to control timing and dwell. Dwell is active when EST is high, and spark happens when EST signal falls.

• If the crank pulse width pattern is not recognized the Diag#1 tens digit will increment

• Missing crank pulses will increment the Diag#1 ones digit• Extra crank pulses will most likely increment the Diag#1 1k, tens, and ones digits• Missing cam pulses will increment the Diag#1 tens digit• Extra cam pulses in the wrong place will increment the Diag#1 ones digit

GM LSx 24 Tooth

GM First Gen Northstar• ECU utilizes stock module for signal conditioning of magnetic pickups

and switching coil primary current• ECU is triggered on the falling edge of the module’s REF signal at ~2.3V • No internal pullup is activated for the crank/REF• The BYPASS signal is generated by the ECU (by the switchable pullup on

the cam “input”) to assert control of the timing. When low (or open) the module controls timing and dwell. When high the ECU controls timing.

• The EST signal is generated by the ECU to control timing and dwell. Dwell is active when EST is high, and spark happens when EST signal falls.

• Overall the operation is similar to a small-cap HEI as far interaction with the ECU, except for the angular location of the REF pulse

Holley DIS 60-2 with Cam Sync• Crank input reacts to the falling edge of the crank sensor’s signal at ~2.3V• Cam input reacts to the falling edge of the cam sensor’s signal at ~2.3V• An internal pullup is activated for the crank and the cam• The ECU decodes the 60-2 crank pattern and uses the cam pulse to establish cycle sync• The crank tooth before the missing teeth establishes the valid window for the cam signal.

Nominally this is at ~78deg BFTDC#1, which means the falling edge of the cam signal must be between 78 crank degrees before FTDC#1 and 438 degrees before FTDC#1. To make it easy to remember I recommend 180 crank degrees before FTDC#1, or BDC before compression.

• Eight individual EST signals with two events per cycle are generated by the ECU to control timing and dwell, but only four are used. Dwell is active when EST is high, and spark happens when EST signal falls. Baseline dwell is ~1.8ms.

• Extra or missing crank pulses will increment the Diag#1 tens digit• If the crank signal drops out the Diag#1 hundreds digit will increment• If the cam signal drops out, falls out of proper phase the Diag#1 tens digit will increment• Extra cam pulses in the wrong place will increment the Diag#1 ones digit

Holley DIS 60-2 w/HE, Offset 0

Holley DIS 60-2 w/HE, Offset 10

Holley DIS 60-2 without Sync• Crank input reacts to the falling edge of the crank sensor’s signal at

~2.3V• An internal pullup is activated for the crank• The ECU decodes the 60-2 crank pattern to establish crank angle• The crank tooth after the missing teeth is nominally at ~60deg

BFTDC#1• Eight individual EST signals with two events per cycle are generated

by the ECU to control timing and dwell, but only four are used. Dwell is active when EST is high, and spark happens when EST signal falls.

• Extra or missing crank pulses will increment the Diag#1 tens digit• Missing crank pulses cause the timing to shift for all cylinders• Extra crank pulses will not shift the timing for all cylinders

Custom

• There are options to use various combinations of target geometry and sensor types for crank and cam

• The ECU detects the falling zero crossing for magnetic sensors, which is the opposite of many aftermarket applications

• Try to avoid magnetic cam sensors: Hall effect sensors function much better during cranking and at low speeds.

• The ignition output type and dwell are also selectable• The “Points Out” selection is to trigger a “Points Input” of

another device, NOT to drive a coil directly• EST outputs are logic signals and are not for driving strongly

biased inputs (CD box inputs)

60-2 Crank Setup

• TDC tooth number is the number of teeth between the sensor and the index gap when the engine is at TDC of the first cylinder in the firing order

• The timing offset can be used to make small adjustments. Positive numbers advance timing relative to crank signals.

• When using a cam sync, follow the same rules as a Holley 60-2 DIS setup

60-2 Crank, Tooth 11, Offset 0

1 pulse/fire with Sync

• Set the cam pulse so that #1 crank pulse is the second crank pulse after the cam pulse, or the first cylinder in the firing order should correspond to the second tooth after the cam pulse.

• Generally for V8s with normal ignition reference angles this means the cam pulse should happen at about 180 degrees before #1 firing TDC, or BDC before compression.

• The cam pulse should not happen too close to a crank event. Ideally it should occur midway between crank events.

Waveforms with 1pulse/fire Mag Crank and 1 pulse/cycle Mag Cam

NormalDiag#1 Ones Digit- SteadyDiag#1 Tens Digit- SteadyCalculated RPM- Steady

Missing Crank PulsesDiag#1 Ones Digit- Increments

Diag#1 Tens Digit- SteadyCalculated RPM- Non-zero Dips

Missing Cam PulsesDiag#1 Ones Digit- Steady

Diag#1 Tens Digit- IncrementsCalculated RPM- Dips to Zero, Error, Syncing, then Normal

Extra Crank PulsesDiag#1 Ones Digit- Increments (Second)

Diag#1 Tens Digit- Increments (First)Calculated RPM- Can Show Falsely High, Error, Syncing, then Normal

Extra Cam PulsesDiag#1 Ones Digit- Increments Two at a Time

Diag#1 Tens Digit- SteadyCalculated RPM- Steady

Intermittent Cam SignalDiag#1 Ones Digit- Increments when Cam Pulses are Too FrequentDiag#1 Tens Digit- Increments when Cam Pulses are Too Infrequent

Calculated RPM- Dips to Zero, Error, Syncing

The Blanking Window for Crank PulsesThe time between the last two pulses is used to know when to expect the next pulse- no sooner than roughly half the previous period. If a

pulse happens too early relative to this expectation, it is disregarded. This does not affect timing.Diag#1 Ones Digit- SteadyDiag#1 Tens Digit- SteadyCalculated RPM- Steady

Extra Crank Pulses Can Cause Real Pulses to be in the Blanking WindowIf a noise pulse happens just before a real crank pulse, the noise will be treated as a real pulse and the real pulse will be disregarded as noise.

This can cause a timing shift. Diag#1 Ones Digit- SteadyDiag#1 Tens Digit- Steady

Calculated RPM- False High Followed by False Low, or it could also be steady

Quick Generalizations

• For Diag#1 with 1pulse/fire– Ones digit increment means not enough crank

pulses between cam pulses (missing crank pulses or extra/early cam pulses)

– Tens digit increments means too many crank pulses between cam pulses (extra crank pulses or missing cam pulses)


• Normal Diag#1 activity– It is normal for the 10k digit to increment during

running, but the rest of the digits should be static. This is essentially a cycle counter (one increment per two crank revs) and can be another tool to distinguish extra cam pulses, which cause premature incrementing.

– It is also normal to have Diag#1 increments of other digits during cranking while ECU is establishing cycle sync


• Diag#1 activity when running– Do not ignore!– Many things that cause Diag#1 errors will result in timing shifts– Problems that only occur at high speed and load can be from

sensor and/or target vibration• Unreasonable spikes or dips in engine speed

– Do not ignore!– For systems without a cam sync this can be one of the only

indicators of noise or signal dropout– Be suspect of rates of change >20kRPM/sec– Be suspect of quick jumps to 4/3 or 4/5 expected engine speed

followed by a quick return to normal

Tools for Deeper Analysis

• Sometimes Diag#1 does not definitively explain what is going on

• The ECU can take a special high speed internal log of crank and cam sensor activity, which allows you to visualize the sensor signals vs time

• This is saved in the ECU as an SL file (System Log) that you can download like a normal internal datalog file

• Although it is a record of logical states (not analog voltage levels), you can tell when a magnetic sensor has crossed the arming threshold

• It is also useful to verify cam phasing relative to crank

Preview of S-Log Viewer

Future Changes

• We are continually improving the functionality of the diagnostic channels and software tools

• System log functionality is already implemented in current firmware but requires a keycode to unlock

• The SL viewer will be released with the next major revision of PC software (2.x)

• RTC Timestamp to on SL header• Notice of Diag#1 increments post engine start-

something similar to a check engine light

holley efi crank-cam setup and diagnostics

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