About the Alpha engine
The Alpha family is Hyundai's small four-cylinder from the 1990s. It shows up in the Excel (X3) and S Coupe, and it's the heart of the Excel racing classes. All versions share a 1-3-4-2 firing order, but there are meaningful differences between the single-cam and twin-cam engines, so identify yours before you start wiring.
Variants and displacements
| Code | Displacement | Layout | Notes |
|---|---|---|---|
| G4EH | 1,341 cc (1.3L) | - | Smallest version |
| G4EE | 1,399 cc (1.4L) | - | - |
| G4EK | 1,495 cc (1.5L) | SOHC, 12 valves | MAF, EV1 injectors, 10.0:1 compression |
| G4EK Turbo | 1,495 cc (1.5L) | SOHC, 12 valves | 7.5:1 compression, Garrett T15 turbo |
| G4FK | 1,495 cc (1.5L) | DOHC, 16 valves | TMAP, EV6 injectors, 10.0:1 compression |
| G4ED | 1,599 cc (1.6L) | DOHC, 16 valves | 10.0:1 compression |
Which car has which engine
- Excel X3, 1994 to 1996: G4EK 1.5L
- Excel X3, 1997 on: G4FK 1.5L
- S Coupe: G4EK
- S Coupe Turbo, 1992 to 1994: G4EK Turbo
Crank and cam triggers
The crank wheel is part of the crankshaft near the flywheel end and uses the common 60-2 pattern: sixty tooth positions with two left out to mark a reference point. The cam has a single tooth, read by a sensor at the flywheel end of the head. The crank uses a magnetic reluctor sensor and the cam uses a Hall effect sensor, so they wire differently.
| Sensor | Sensor pin | Function | Haltech wire |
|---|---|---|---|
| Crank (reluctor) | 1 (D) | Reluctor positive | Trigger cable, yellow |
| 2 (E) | Reluctor negative | Trigger cable, green | |
| 3 (F) | Shield | No Haltech connection | |
| Cam (Hall effect) | 1 (A) | Switched 12V supply | Home cable, red |
| 2 (B) | Home signal | Home cable, yellow | |
| 3 (C) | Signal ground | Home cable, blue |
If you get RPM but it's jumpy or drops out at higher speed, swap the reluctor positive and negative wires first. A reversed reluctor is the most common crank signal fault we see. Our Hall effect or reluctor article explains the difference.
Ignition
The coil pack is a waste-spark design, meaning cylinders 1 and 4 share one coil and 2 and 3 share the other. The coils need an external igniter, because on the factory setup the igniter lives inside the OEM ECU. Haltech's dual channel igniter (HT-020002) is a good match.
| Coil pack pin | Function |
|---|---|
| 1 | Negative for the cylinder 1 and 4 coil (to igniter channel) |
| 2 | Negative for the cylinder 2 and 3 coil (to igniter channel) |
| 3 | Switched 12V |
Dwell data for this coil is available as a reference chart. Ask us and we'll send it over with advice for your build.
Air, throttle and idle
Throttle position
These engines use a cable throttle body with a conventional throttle position sensor.
MAF or MAP?
Early G4EK engines came with a MAF. Some later variants use a MAP sensor bolted to the plenum instead, and the G4FK uses a combined temperature and pressure (TMAP) sensor, so check which parts your engine actually has. Most Haltech installs delete the MAF. If you keep it, the wiring is:
| MAF pin | Function | Haltech connection |
|---|---|---|
| 1 | Output signal | A spare AVI |
| 2 | Switched 12V | - |
| 3 | Sensor ground | Signal ground (black/white) |
| 4 | Power ground | - |
For load sensing we'd use the ECU's internal MAP sensor on a naturally aspirated engine. On a boosted engine, fit an external sensor like the 3 bar GM MAP sensor on a spare AVI.
Idle valve
Idle air is handled by a three-pin bypass air control valve that the ECU drives with two outputs, one to open and one to close.
| Valve pin | Function | Haltech connection |
|---|---|---|
| 1 | Open coil | Spare output |
| 2 | Supply | Switched 12V |
| 3 | Close coil | Spare output |
Temperature and knock sensors
The coolant and air temperature sensors are both two-wire and not polarity sensitive. Connect one pin to a spare AVI and the other to signal ground. Use an AVI with a selectable pull-up and turn it on. If your AVI has no pull-up, add an external 1k resistor from the signal to 5V. MAP-equipped variants have a second air temp sensor built into the MAP sensor body.
There's one knock sensor: pin 1 is the knock signal and pin 2 goes to signal ground.
Oxygen sensors
From the factory these cars use a four-wire narrowband sensor:
| Wire | Role | Haltech connection |
|---|---|---|
| Black | Sensor signal | AVI 1 or AVI 6 |
| Gray | Signal return | Signal ground (black/white) |
| White | Heater supply | Switched 12V |
| White | Heater ground | Chassis ground (not signal ground), or a spare output |
Many OEM ECUs pulse the heater ground rather than tying it straight to ground, and a Haltech can do the same using a spare injector or stepper output. Heaters are commonly 12 W or 18 W. With an 18 W heater, keep duty to about 50% or less so you don't overload the ECU output. For a post-cat sensor, don't turn the heater on until the engine is fully warm. Water in a cold exhaust can crack a hot heater element, which is why factory strategies often wait until the car has been driven for a while.
For tuning, we strongly recommend a WB1 single-channel CAN wideband kit, with its Bosch LSU 4.9 sensor going in place of the pre-cat sensor. The sensors take a 22 mm (7/8 in) wrench or socket.
Injectors
Flow figures are taken with the injector held wide open. If your fuel system uses a fixed pressure that isn't referenced to manifold pressure (common on returnless systems), the effective flow changes with boost or vacuum, so it has to be mapped against manifold pressure for accurate fueling. The stock G4EK injectors flow roughly 172 cc/min (about 16 lb/hr). Common Bosch parts for these engines:
| Bosch part | Fitted to | Flow (cc/min) | Approx. lb/hr |
|---|---|---|---|
| 0-280-150-773 | 1.5L | 150 | 14.3 |
| 0-280-150-776 | 1.5L | 192 | 18.3 |
| 0-280-150-742 | 1.5L and 1.6L | 192 | 18.3 |
| 0-280-150-745 | 1.6L | 235 | 22.4 |
Published dead time data for these injectors isn't available. Our injector dead time guide walks through finding it on the car.
Factory ECU pinouts
If you're building a plug-in style adapter or tracing an existing loom, you'll want the OEM ECU pinouts for the 1994 to 1996 G4EK Excel and the 1998-on G4FK Excel. They're diagrams, so we don't reproduce them here. Ask us and we'll send them over with advice for your build.
Alpha engine FAQ
Do I need a new igniter to run a Haltech on a G4EK?
Yes. The factory igniter is inside the OEM ECU, so once that ECU is gone the coils need an external igniter.
Can I tune an Excel with the stock narrowband sensor?
Not properly. A narrowband only tells you rich or lean of stoichiometric. Fit a wideband for tuning and keep the narrowband only if you need it for emissions.
Wiring an Excel race car? Book a free consultation and we'll help you pick the right ECU.
