Why rotaries need their own setup notes
A Mazda rotary has two spark plugs per rotor, usually two stages of injectors, and trigger hardware that changed several times across the RX-7, Cosmo and RX-8. None of it is hard once you know the rules, but guessing gets you a no-start or, worse, a misfire you chase for days. Below is how we approach a rotary install on the Elite platform, grouped by the job you're doing rather than by model.
If you're new to rotaries, read our 10 things you need to know about rotary tuning alongside this page.
Step 1: know which engine you have
These notes focus on the turbocharged engines, plus the naturally aspirated RX-8. Here's how we tell them apart on the bench or in the car:
| Engine | Where you'll find it | Giveaways | Ignition from the factory |
|---|---|---|---|
| 12A Turbo | JDM Series 3 RX-7, some HB Cosmos | Orange cap on a carb-style throttle body, tiny ports. Bolts into any first-gen RX-7 but makes little power | Distributor with a boost retard diaphragm |
| 13B-T Series 4 | Mostly 1986-88 FC RX-7 | Rod-driven mechanical oil metering pump, twin-scroll turbo, one TPS, straight intercooler pipe, 8.5:1 compression | Waste spark on lead, toggle-type trail igniter |
| 13B-T Series 5 | Mostly 1989-91 FC RX-7 | Stepper-motor oil metering, two TPS, bigger single-scroll turbo, tapered intercooler pipe, 9.0:1 compression | Same as Series 4 |
| 13B-RE | JC Cosmo only, all automatics | Sequential twin turbos, very large end-plate ports, serpentine belt, no flywheel inspection cover | Not covered in our notes, confirm on the car |
| 13B-REW | FD RX-7 Series 6, 7 and 8 | Like the Cosmo motor but smaller ports and bigger secondary injectors | Waste spark |
| 20B | JC Cosmo only, automatic | Three rotors, sequential twins | Two dual-toggle igniters. The factory igniters will not run on a Haltech |
| 13B-MSP (Renesis) | RX-8 | Side exhaust ports, 10.0:1 compression, drive by wire, motorized port actuators, naturally aspirated. Manuals carry three injectors per rotor | Direct fire |
| 26B / 4-rotor | Le Mans race engine, never sold to the public | Aftermarket 4-rotor kits use custom cranks and end plates | Needs an Elite 2500 for 4-rotor support |
Step 2: displacement and firing order
For VE-based fuel tuning, the Elite needs the engine's true swept volume. Enter these numbers, not the "equivalent" piston-engine figures people quote online:
- 10A (2 rotors): 982 cc, firing 1-2
- 12A (2 rotors): 1146 cc, firing 1-2
- 13B (2 rotors): 1308 cc, firing 1-2
- 20B (3 rotors): 1962 cc, firing 1-2-3
- 26B (4 rotors): 2616 cc, firing 1-3-2-4
Step 3: triggers
Every Mazda rotary uses variable reluctor (magnetic) sensors, and set up properly they all trigger on the falling edge. What differs is where the sensors live and how the factory wired their grounds.
FC RX-7, Cosmo 13B and 20B: the CAS
These use a crank angle sensor that looks like a distributor and turns at half engine speed. Pop the inspection cover and you'll see a 24-tooth trigger wheel and a separate sync wheel, each with its own reluctor pickup. Wire the red NE+ lead to Trigger + and white NE- to Trigger -. The green G+ lead goes to Home + and the white/black G- to Home -. Use the yellow and green wires in each shielded 4-core.
FD RX-7: crank-mounted sensors
The FD moved to two sensors at the crank pulley: a 12-tooth inner wheel for trigger and a single outer tooth for home. The pattern the ECU sees is equivalent to the FC's CAS. The catch is that Mazda tied both sensor negatives together inside the factory loom, so the right settings depend on how you wire it:
- Through the factory ECU connector: the black wire (12-tooth sensor, pin 2) goes to Trigger +, the white wire (1-tooth sensor, pin 2) to Home +, and the shared red negative to signal ground (the blue wire in the trigger 4-core). Set both Trigger Ground Ref and Home Ground Ref to
Enabled. - Straight to the sensors (our preference): run each sensor's own negative back to the ECU. On the 12-tooth sensor, pin 2 black is Trigger + and pin 1 green is Trigger -. On the 1-tooth sensor, pin 2 white is Home + and pin 1 red is Home -. Set both ground reference options to
Disabled.
Getting the ground reference setting backwards for your wiring is one of the most common rotary no-start causes we see.
Trigger settings at a glance
| Setting | FC 13B / 20B Cosmo | FD 13B | RX-8 |
|---|---|---|---|
| TDC angle | 5 | 5 | 35 (not yet verified, check with a timing light) |
| TDC offset table | Required | Required | Required |
| Trigger and home sensor type | Reluctor, falling edge, filter 0 | Reluctor, falling edge, filter 0 | Reluctor trigger, falling edge, filter 0 |
| Ground ref | Disabled | Enabled (factory loom wiring) | Disabled |
| Quick start | Disabled | Disabled | Disabled |
| Ignition | Factory igniters not supported. 20B must run direct fire | Waste spark, falling edge, constant charge | Direct fire, falling edge, constant charge |
Whatever the model, confirm base timing with a light before you tune anything. Our guide to using a timing light covers the process.
Step 4: ignition, lead and trail
Each rotor housing has two plugs. The lead plug is the lower one (the housing is stamped "L") and the trail plug is the upper one (stamped "T"). Haltech's approach is to treat a 2-rotor like a 2-cylinder with one plug per cylinder: the lead coils take the first ignition outputs, and the trail coils are handled as extra outputs after them. That rule scales to 3 and 4 rotors.
| Ignition output (wire color) | Pin: Elite 1000-2500 / 550-750 | 2-rotor direct fire | 2-rotor waste spark | 3-rotor (20B) | 4-rotor (26B) |
|---|---|---|---|---|---|
| #1 (yellow/black) | A3 / 3 | Lead, rotor 1 | Both leads (one dual-post coil) | Lead 1 | Lead 1 |
| #2 (yellow/red) | A4 / 4 | Lead, rotor 2 | Not used | Lead 2 | Lead 2 |
| #3 (yellow/orange) | A5 / 5 | Trail, rotor 1 | Trail 1 | Lead 3 | Lead 3 |
| #4 (yellow/green) | A6 / 6 | Trail, rotor 2 | Trail 2 | Trail 1 | Lead 4 |
| #5 (yellow/brown) | A7 / - | - | - | Trail 2 | Trail 1 |
| #6 (yellow/blue) | A8 / - | - | - | Trail 3 | Trail 2 |
| #7 (yellow/violet) | B17 / - | - | - | - | Trail 3 |
| #8 (yellow/grey) | B18 / - | - | - | - | Trail 4 |
3-rotor engines need an Elite 2000 or 2500 for the extra outputs, and 4-rotor support comes from the Elite 2500.
Factory coil packs
- FC RX-7: the lead side is a dual-post coil with a single-channel igniter bolted on. The trail side uses two coils and a "toggle" igniter, where one ECU wire sets the timing and a second wire tells it which coil to fire. Older Haltech ECUs handled it, but the Elite series cannot drive the FC trail igniter. Plan on a modern igniter such as an HPI6 or smart coils. Both factory igniters ground through their cases, so if you keep any of them, bolt them to clean chassis ground.
- FD RX-7: coils sit under the intake with a 3-channel igniter on the inner fender. Lead is a dual-post coil fired in waste spark, trail is two separate coils. The igniter plug's light green wire (pin 3) is the lead trigger and goes to ignition output 1. Brown (pin 8) is trail 1 on output 3, and brown/black (pin 6) is trail 2 on output 4. Pin 5 (black/white) is switched 12V. Configure waste spark, constant charge, falling edge.
- RX-8: four coils with built-in igniters, so they wire straight to the ECU. Pin A is the trigger signal, B grounds to the rotor housing and C is 12V. Use direct fire, constant charge, falling edge.
Dwell should come from the coil's own data. See our dwell time article, and if you're unsure whether a coil has an igniter inside, here's how to tell.
Step 5: injectors and staging
Rotaries run primaries in the intake runners and secondaries that come in with load. Keep the stages in order on consecutive injector outputs: on the Elite 2000/2500, outputs 1 to 4 are pins A19 to A22 (blue, blue/black, blue/brown, blue/red), 5 and 6 are A27 and A28 (blue/orange, blue/yellow), and 7 and 8 are B29 and B30 (blue/green, blue/violet).
- 2-rotor (including the automatic RX-8): primaries on outputs 1 and 2, secondaries on 3 and 4.
- 3-rotor: three primaries on outputs 1 to 3, three secondaries on 4 to 6.
- 4-rotor: primaries on 1 to 4, secondaries on 5 to 8.
- Manual RX-8: six injectors in three stages. Mazda calls them Primary 1, Primary 2 and Secondary. Wire front then rear rotor for each stage: outputs 1-2 are stage 1, 3-4 are stage 2 and 5-6 are stage 3.
Factory injector sizes
| Engine / chassis | Primary | Secondary | Third stage |
|---|---|---|---|
| 12A Turbo, JDM first-gen RX-7 | 800 cc | - | - |
| 13B 6-port NA, US first-gen RX-7 | 720 cc | - | - |
| 13B 6-port NA, FC | 430 cc | 430 cc | - |
| 13B Turbo, FC and JC Cosmo | 550 cc | 550 cc | - |
| 13B Turbo, FD | 550 cc | 850 cc | - |
| RX-8 manual | 290 cc | 380 cc | 380 cc |
| RX-8 automatic | 290 cc | 480 cc | - |
| 20B, JC Cosmo | 550 cc | 550 cc | - |
Step 6: throttle position and MAP
- Series 4 TPS (one sensor only): it hits full scale at roughly 30% real throttle, which makes it useless for serious tuning. Swap to a Series 5 throttle body or sensor setup.
- Series 5 TPS (two sensors): one covers the full range, the other is the same short-range sensor the Series 4 used. The full-range sensor is the one Mazda added for the electronic oil metering. Connect only the full-range sensor to the Haltech.
- FD TPS: signal, 5V and ground are all you need. The idle switch contact isn't used.
- MAP: on the FC we use the ECU's internal MAP sensor. On the FD the factory sensor works, but the internal one is still our first choice.
Common rotary problems
| Symptom | Usually |
|---|---|
| Cranks, RPM shows but no spark on the trail plugs (FC) | Still using the factory toggle igniter, which the Elite can't drive |
| No RPM signal, or it drops in and out (FD) | Ground ref setting doesn't match how the sensor negatives are wired |
| Throttle reads 100% at part throttle | Series 4 short-range TPS, or the wrong Series 5 sensor wired |
| Fuel model way off from the start | Displacement entered as a piston-engine equivalent instead of true swept volume |
| Timing light doesn't match the ECU | TDC angle not confirmed, especially on the RX-8 |
Rotary FAQ
Is there a plug-in option for the FD RX-7?
Yes. We stock the Elite 2500 plug 'n' play kit for the Series 7 and 8 FD, and for FCs there are terminated harnesses like the Elite 1500 13B S4/5 kit.
Can I keep the factory oil metering pump?
It depends on the series and how the pump is driven. Talk to us before you decide, because oil metering mistakes are expensive on a rotary.
Which Elite do I need for a 20B or 4-rotor?
A 3-rotor needs at least an Elite 2000 or 2500 for six ignition and six injector outputs. A 4-rotor needs the Elite 2500. Book a free consultation and we'll spec the rest of the system with you.
