January Diagnostic Challenge

[Jeremy airjer W]

1999 Honda Accord 2.3 liter

Customer stated the vehicle had no power when cold. Check engine light is on. Had codes P0302, P0303, and P0304 (#2, #3, #4 cylinder misfires).

What I found

- Engine runs noticeable rough at idle with low RPM's

- Engine bogs down when opening the throttle from idle and will run better at higher RPM's

- cylinders 1,3, and 4 had the correct spark plug application but they where slightly worn.

- #2 cylinder had an incorrect champion double platinum plug.

- All 4 cylinders had good spark and good injector pulse.

- Fuel pressure is correct at 30-38 PSI.

- All four cylinders had 150psi of compression.

- There are no vacuum leaks.

- Upstream O2 sensor is working

- MAP sensor is reading correctly

- Timing is right on

- Vacuum gauge holds steady at 18-19" at idle

- If I disable cylinders 2,3, or 4 the engine will continue to run but there is only a slight, barely noticeable and sometimes unnoticeable RPM change.

- If I disable cylinder 1 the engine will stall.

- If I add a shot of car spray at idle the engine smooths out and the RPM's return to normal.

What do you think?

[cam7069]

How many miles?

[Scott K]

Bad or plugged injectors? Have you checked resistance on the injectors? Spray pattern bad?

[Dave S]

Was there anything done to the car before the issue started? Were plugs and/or wires replaced and not put back on the right cylinders?

[Jeremy airjer W]

How many miles?

160k +

[Jeremy airjer W]

Bad or plugged injectors? Have you checked resistance on the injectors? Spray pattern bad?

I didn't ohm check them but I did do an injector balance test. I could not check them for spray as they are not mechanically attached to the fuel rail.

With the PSI starting at 35psi and using 40 10ms pulses this was the result.

#1 - 31psi

#2 - 32psi

#3 - 32psi

#4 - 32psi

[Jeremy airjer W]

Was there anything done to the car before the issue started? Were plugs and/or wires replaced and not put back on the right cylinders?

Apparently there was some wiring repair for the injectors however I was not able to identify where they made the repair. An injector had also been replaced, unknown which one. The #2 plug had also been replaced when the other repairs where made.