What the trigger page actually decides
Every fuel and spark event an Elite ECU schedules is timed from the trigger system. The ECU counts teeth going past the crank sensor (the Trigger input) to work out engine speed and crank angle, and it watches the cam sensor (the Home input) to figure out which half of the 720 degree cycle the engine is in. Get the trigger page right and the engine starts, idles and times accurately. Get it wrong and you'll see no RPM, erratic RPM, backfires or timing that drifts.
The page splits into three areas: the overall trigger configuration, the Trigger (crank) signal setup and the Home (cam) signal setup. Below those sit an optional TDC offset table and a set of diagnostic channels that are your best friend when something isn't right.
Trigger configuration
Trigger Type
Start here. Pick your engine from the list and ESP loads the tooth pattern it expects, which is how the ECU knows both RPM and when to fire each injector and coil. Clicking a type opens a help box describing the crank and cam patterns, which is a quick way to confirm you've chosen the right one.
If your engine runs an aftermarket wheel or something not on the list, choose Generic Missing Tooth or Generic Multi-tooth and describe the wheel yourself. If your engine isn't listed but shares a pattern with one that is, selecting that engine usually works. Haltech also takes requests to add engine types in future updates.
Number of Teeth and Number of Missing Teeth
These only unlock with the generic types. Count the teeth as though the gap were filled in. A wheel with 35 real teeth and one blank space is a 36 tooth wheel, so you enter 36, and with Generic Missing Tooth you'd then enter 1 as the missing tooth count.
Trigger Signal Location
Tell the ECU whether the trigger wheel turns with the crankshaft or at cam speed, as it does in a distributor. This changes how the ECU converts tooth events into crank degrees.
TDC Offset Angle
This is the angle between the cylinder 1 reference tooth and cylinder 1 top dead center. It can be anywhere from 0 to 720 degrees. The goal is simple: timing the ECU commands must match timing you see on the crank. You set it with a timing light while Ignition Lock Mode holds a fixed advance, adjusting the offset until the light agrees with the software. There's no shortcut here, so budget the time. Our ignition timing calibration guide walks through the process.
TDC Offset Angle Table Enable
Tick this to open the TDC Offset Angle Table. Sensor response and ignition hardware both add small delays, so timing that's locked perfectly at idle can drift a degree or two as RPM rises. The table lets you nudge the offset across the RPM range so the ECU and the crank agree everywhere. Check with the timing light at a few RPM points and only fill the table in if you actually see drift.
RPM Filter Level
Smooths the RPM signal on aggressive engines, such as big cams or lightweight flywheels, where RPM jumps around enough to make tuning awkward. The range is 0 (no filtering) to 4 (maximum). We leave it at 0 unless the logged RPM is visibly noisy.
Quick Start
With direct fire ignition and sequential injection, Quick Start lets the engine fire before full cam sync by running wasted spark and semi-sequential injection while RPM is below the Max Cranking RPM. The engine catches sooner. Turn it off with CDI ignition systems and on methanol engines.
Reluctor vs Hall effect: the sensor settings
Both the Trigger and Home inputs have nearly identical sensor options, so we'll cover them once. The Trigger input is what some manuals call the reference, crank sensor or NE signal. The Home input is also called the sync, cam sensor or G signal.
| Reluctor (VR) | Hall effect / optical | |
|---|---|---|
| Wires | Usually 2, sometimes a third for shielding | 3 or more, because it needs power |
| Signal | Analog AC wave: swings positive as a tooth approaches, negative as it leaves | Digital square wave that snaps between on and off |
| Pull up | Not needed | Needed, either the ECU's internal one or the sensor's own |
| Ground Reference | Available | Not used |
The Custom sensor type exists for unusual sensors and needs advanced setup. Only use it if Haltech support tells you to, along with the Digital Reference and Signal Coupling options it unlocks. For reference, AC coupling suits symmetrical signals like a reluctor, and DC coupling suits one-sided signals like a Hall sensor.
Signal settings and our advice
| Setting | What it does | Our advice |
|---|---|---|
| Edge | Chooses whether the rising or falling edge of each tooth counts | Use what the engine type calls for. Haltech can supply the correct edge for most patterns |
| Filter Level | Cleans up a noisy sensor, levels 0 to 3 | Start at 0. Only go higher if it measurably improves the signal. Needing a lot of filtering points to wiring, interference or a failing sensor |
| Pull Up: Disabled | No internal resistor | Reluctor sensors, Hall sensors with a built-in pull up, or when sharing the signal with an OEM ECU that already provides one |
| Pull Up: Enabled | 2.2k Ohm resistor from the signal to 5V | Our default for a standalone Hall sensor |
| Pull Up: Strong | 550 Ohm resistor from the signal to 5V | Only when a sensor needs more pull up than the standard setting gives. Confirm with a scope or log |
| Ground Reference | Measures a reluctor against the ECU signal ground instead of its own negative wire | Only when the + and - wires can't both run straight to the sensor, or the sensor calls for it |
| Edge Rejection Ratio | Ignores any signal for a set percentage of the time between teeth | Off by default (ratio 20 when enabled). Useful on noisy setups, but too high can miss real teeth on fast-revving engines |
| Time Out Ratio | How long the ECU waits before deciding the engine has stopped | Leave at the default of 3 unless you have a reason |
Home signal sync options
The crank sensor alone can tell the ECU where the crank is within one revolution. The cam turns at half speed, so a single cam tooth is enough to tell the ECU which revolution it's in, and that's what unlocks true sequential injection and direct fire. Engines with variable cam timing usually have several cam teeth, which the ECU needs to measure cam position accurately.
- Minimum RPM: with Quick Start on, the home signal is ignored below this RPM. Sequential injection runs as semi-sequential and direct fire runs as wasted spark until RPM passes the threshold. Above it, the home signal is latched and the ECU switches to full sequential. Dropping back to 0 RPM resets it.
- Synchronisation Mode: Always: the home signal is used for engine position all the time, except below Minimum RPM if that's enabled.
- Synchronisation Mode: Until Full Sync: once the ECU has held full sync for 8 engine cycles, it stops listening to the cam sensor and runs from the crank alone. This is only offered on Generic Standard Full Cycle and some missing tooth and extra tooth patterns. It's handy when the cam signal gets noisy at high RPM or moves around with cam timing changes.
Reading the trigger diagnostic channels
When an engine won't start or cuts out, these channels usually tell you why in seconds. Crank it with a log running and watch them.
| Channel | What to look for |
|---|---|
| Trigger Synchronisation Level | None, Cylinder, Half, Full or Error. A sequential engine should reach Full. Stuck at Half usually means the home signal isn't being seen |
| Trigger Synchronisation State | Steps from Stopped through First Tooth, First Ref Event and First Unique Ref Event to Running. Where it stalls tells you which part of the pattern it's waiting on |
| Trigger System Errors | 1: No Home, 2: Home Position Error, 3: Reference Detection Error, 4: Home Tooth Count Error, 5: Trigger Tooth Count Error, or combinations of them |
| Trigger Tooth Count | Teeth counted between reference events (or on the whole wheel for standard triggers). Compare it with what the pattern should have |
| Error count and at-error channels | How many errors have occurred, plus the tooth count, home tooth count, tooth period, previous tooth period and sync offset difference captured when the last one happened |
Troubleshooting
| Symptom | Usually |
|---|---|
| No RPM while cranking | Wrong trigger type, pull up disabled on a Hall sensor, or a wiring fault. Check the trigger wiring |
| RPM but sync never reaches Full | Home signal missing or on the wrong edge, or No Home errors |
| Trigger Tooth Count Errors | Noise, a wrong edge, a damaged wheel, or the wrong tooth count on a generic type |
| Home Position Errors at high RPM | Cam signal noise or cam timing movement. Try Until Full Sync if your pattern supports it |
| Timing light disagrees with ESP | TDC Offset Angle not calibrated, or drift that needs the offset table |
Before you fire a new engine, run through checking the crank and cam angle sensors. The rest of the engine setup lives on the Engine and Main pages, and our trigger systems explainer covers the patterns in more depth.
Trigger setup FAQ
My engine isn't in the trigger type list. Now what?
If it uses a common missing tooth or multi-tooth wheel, the generic types cover it. If it has an OEM pattern that matches another engine, select that engine. If you're unsure, send us the wheel and cam details and we'll help you pick.
Should I enable the pull up on my crank sensor?
Only for a Hall or optical sensor without its own pull up. Reluctors never need it, and if the Elite shares the signal with a factory ECU, the factory ECU already supplies one.
Do I need to set TDC offset if I used a base map?
Yes. Base maps get you close, but sensor and wheel placement vary. Always confirm with a timing light before tuning ignition.
