1987 Toyota Camry Cylinders 2 and 3 Not Firing: Causes and Diagnostic Approach

When cylinders 2 and 3 quit firing on a 1987 Toyota Camry, it can feel like the car is messing with you. The engine runs rough, power drops off, and no matter how many ignition parts you’ve just replaced–wires, cap, rotor, plugs–it still won’t smooth out. That’s usually the moment you realize this isn’t just an ignition problem. Something’s keeping those two cylinders from getting fuel, and on this car that often points to the injector signal not making it where it needs to go.

A quick, real-world picture of how the system works

Your Camry’s fuel injection setup is basically a coordinated handoff between sensors, the ECU (engine computer), and the injectors themselves. Sensors tell the ECU what the engine is doing–speed, position, load–then the ECU decides when each injector should open. When it’s time, the ECU sends a pulse to the injector, the injector pops open for a split second, and fuel gets sprayed into the intake so the cylinder has something to burn.

So if cylinders 2 and 3 are dead while the others are working, the engine is practically shouting one thing: those injectors aren’t being triggered (or they can’t respond even if they are).

What usually causes “only 2 and 3” to fail

This is where things get surprisingly specific. Two cylinders dropping out together often means they share something in common–wiring, a connector, a ground path, or a driver inside the ECU.

Here are the most common culprits:

1. Wiring or connector trouble

The harness to the injectors lives a hard life–heat, vibration, oil, moisture. A cracked wire, a loose pin, or corrosion in a connector can easily cut the ECU’s signal off. And yes, it can happen in a way that only affects two injectors.

1. ECU failure (or partial ECU failure)

People hesitate to blame the ECU because “everything else still works.” But ECUs can fail in sections. One injector driver can die while the rest of the computer continues operating like nothing’s wrong.

1. Injector driver circuit issues

Inside the ECU are circuits that actually “switch” the injectors on and off. If the driver for #2 and #3 is damaged, those injectors won’t get the pulse they need, even if the ECU is otherwise awake and communicating.

1. Ground problems

Injectors need solid electrical paths to work correctly. A weak ground won’t always kill the whole engine–it can knock out a pair, especially if they share grounding points or wiring routes.

1. Sensor inputs that confuse timing

If the ECU loses a clean crank/cam signal (or gets a distorted one), injector timing can go sideways. Usually that causes broader symptoms than just two cylinders, but it’s still on the list–especially if the problem comes and goes.

How a good technician typically tracks it down

Pros don’t guess–they confirm. The process usually looks like this:

• Start with a careful visual inspection of injector connectors and the harness. Broken insulation, green corrosion, bent pins, loose clips–small stuff matters here.
• Pull ECU fault codes (if available) to see whether the computer is flagging an injector circuit, sensor issue, or internal malfunction.
• Test power and continuity with a multimeter. The goal is to prove whether the injector is getting voltage and whether the ECU control wire is intact.
• Check injector pulse with a noid light or, even better, a scope. This tells you instantly whether the ECU is attempting to fire injectors 2 and 3.
• Verify grounds under load, not just visually. A ground can look fine and still fail electrically.

Easy mistakes that waste time

• Assuming new ignition parts mean the misfire can’t be fuel-related. Ignition and fuel problems can feel identical from the driver’s seat.
• Writing off the ECU too quickly–or refusing to consider it at all. ECUs can fail in narrow, frustrating ways that only affect certain outputs.

Tools and parts that usually come into play

Diagnosing this properly often involves:

• A scan tool (or code-reading method for older systems)
• A multimeter
• A noid light or oscilloscope
• Possible connector or harness repair parts
• In some cases, injectors or a replacement/known-good ECU

Bottom line

If cylinders 2 and 3 aren’t firing on your ’87 Camry and you’ve already handled the ignition side, the smart money is on a missing injector signal–or the electrical conditions needed for that signal to work. Focus on the wiring and connectors first, then confirm injector pulse, then consider grounds and ECU driver failure. Once you find what’s breaking the chain, the fix becomes a lot more straightforward–and the engine can finally run the way it’s supposed to.