KA24DE

Why bother with a KA24DE?

In the US, the 240SX came with the 2.4-liter KA24DE, while Japan got the SR20DET. Plenty of owners swap to the SR, but the KA has real strengths: a cast-iron block and a bucket-over-cam valvetrain that's tough and reliable. With a turbo and proper engine management, it makes a very capable street engine. This guide covers the 1991 to 1994 S13 KA24DE. Most of it also applies to the S14 engine.

Engine basics

Which Haltech ECU?

• Elite 550: the entry point, and a strong fit for a budget build. It covers everything a simple KA24DE needs.
• Elite 1000: a good street-car choice when you want more inputs and outputs than the 550 without paying for race features.
• Elite 1500: the most capable four-cylinder Elite, for race builds that need every feature available.

If you'd rather not wire from scratch, Haltech's plug-in kits for the S15 and S14A Series 2 also plug into the 1991 to 1994 KA24DE. The Elite 1500 S15/S14A S2 kit is one example, and the adaptor harness is sold on its own for Elite 1000 or 1500 owners. A KA24DE base map is available for these kits.

Crank angle sensor (CAS)

Like most 1990s Nissans, the KA24DE combines the crank and cam signals in one optical sensor inside the distributor. A slotted disk spins past the optics. The outer ring has 360 slots and gives Nissan's "1 degree" signal. The inner ring has 4 slots and gives the "180 degree" signal. Because the distributor turns at cam speed, those 360 slots are spread over 720 crank degrees, so each slot is really two crank degrees.

Running both signals in one shielded cable

Because this CAS supplies both signals from one connector, you can tidy the install by carrying Home+ in the trigger cable. The trigger cable's green Trigger- wire isn't needed with this sensor, so you move it to the Home+ pin at the ECU plug and use it as your Home+ wire. The yellow Home+ wire from the home cable is then retired and insulated.

To release pins, unplug the connector at the ECU and press the large white locking tab until it clicks, which lifts the two small tabs on the other side. After moving the pin, check from the pin face that it sits flush with its neighbors, then push the two tabs back down to lock. From then on, remember that the green wire labeled Trigger- is actually carrying Home+.

We have a reference screenshot of the trigger settings for this CAS. Ask us and we'll send it over with advice for your build.

Ignition

Stock distributor and ignitor

The factory setup is one coil feeding the distributor, which routes spark to each cylinder. The coil's two-pin plug has a black/red switched 12V wire and a green/black wire from the ignitor. The coil has no built-in ignitor, so an external ignitor (usually bolted to the coil bracket) does the switching:

Upgrading to coil-on-plug

For higher horsepower we recommend individual coils. You get more spark energy and the ability to trim each cylinder. Mount the coils, wire cylinder 1 to ignition output 1, cylinder 2 to ignition 2 and so on through 4, then change the ignition mode in the main setup from Distributor to Direct Fire.

A suggested dwell table for the stock coil is available. Ask us and we'll send it over.

Sensors and actuators

Throttle position sensor

Mounted on the throttle body with a short pigtail. Pin 1 is 5V supply, pin 2 is signal and pin 3 is signal ground.

MAP sensor

The KA24DE doesn't have one from the factory. The Elite's internal MAP sensor works for mild builds, and for higher boost you'll want an external sensor such as the 3 bar GM MAP sensor or the 5 bar TI MAP sensor.

Idle valves

There are two separate two-pin idle air valves. Only the larger one is controlled by the ECU. It's a pulsed valve, and more duty means more air and a higher idle. Wire pin A to switched 12V and pin B to any spare DPO. Polarity doesn't matter. The smaller valve is an on/off valve that opens when the A/C clutch engages. It isn't wired to or controlled by the ECU.

Coolant temperature

The S13 has two coolant sensors: a single-wire sender for the dash gauge and a two-wire sensor for the ECU. Use the two-wire one. Connect one pin to a spare AVI with the pull-up enabled and the other to signal ground (either way around). Load the Temperature - Nissan S15 Coolant.cal calibration.

Air temperature

The factory sensor lives in the airbox, and on engines this old it's often broken or gone. The ECU needs one, so either use the sensor that comes with the plug-in kit or fit a Haltech 1/8 NPT air temp sensor. Wire it to a spare AVI with the pull-up enabled plus signal ground (polarity doesn't matter) and load Temperature - Haltech 1/8 NPT HT010304.cal.

Knock sensor

The factory sensor is polarity sensitive and grounds itself internally to the block, which isn't good for a clean signal ground. We recommend replacing it with a Haltech knock sensor. If you do keep the Nissan sensor, pin 2 goes to Knock 1 and pin 1 is left unconnected.

MAF sensor

Most Haltech installs delete the MAF, but you can keep it. On the S13 unit, pin 1 is the 0-5V signal, pin 2 is sensor ground and pin 3 is switched 12V. The pin letters are marked on the sensor body.

Base map

Haltech includes base maps for the Elite adaptor harness kits in the ESP software. Import the map rather than opening it as a file, then confirm trigger, injector and sensor settings against your actual engine before the first start. Our free base maps article explains what a base map will and won't do for you. Factory ECU pinout drawings are available on request.

Troubleshooting

KA24DE FAQ

Is a KA24DE worth turbocharging instead of swapping to an SR20?

For many street builds, yes. The iron block is strong, the engine is common in the US, and a turbo KA avoids the cost and hassle of a swap. Good engine management is the key.

Can I keep the stock distributor?

Yes. It works fine on a mild build. Coil-on-plug is the better choice once you're making serious power.

Planning a KA build? Look at the SR20 and RB guides for comparison, or book a free consultation with us.