Misfire on PCM H5

[nathandantzler]

Cylinder 1 Misfire on PCM H5DI 5.3L — DTC 1311 & DTC 301




Hey everyone. I have a 2018 Nautique G21 with the PCM H5DI 5.3L direct injection engine and I'm chasing down a cylinder 1 misfire. Looking for anyone who's dealt with something similar.




THE ISSUE:

Engine runs fine at idle and low RPM, but after about 5 minutes of running under load at higher RPM, I get two fault codes:

- DTC 1311 — Cylinder 1 Misfire Detected

- DTC 301 — Cylinder 1 Emissions Catalyst Damaging Misfire




The fault log shows this code has occurred 127 times, so it's clearly been happening for a while.




WHAT I'VE ALREADY CHECKED:

- Replaced the spark plug on cylinder 1 — plug looked clean and dry, no fouling or oil

- Inspected and cleaned the spark plug wire with contact cleaner

- Plug well looked normal




BACKGROUND:
I recently bought this boat, knowing that had an issue with the NSS, which turned out to be the LINC panoray set to the wrong boat model. (I suspect the screen had been replaced before)
I also previously had DTCs for high side injector faults on multiple cylinders, which turned out to be caused by corrosion on a single pin on the ECM connector. Cleaned it up and that resolved those codes. Not sure if this current misfire is related or not — all the other ECM pins look completely clean, so it may be a separate issue.




MY CURRENT THEORY:

Given that it only misfires under load at higher RPM and runs fine at idle, I'm leaning toward either a weakening coil pack that can't keep up at higher firing frequency, or corrosion in the wiring between the ECM and the coil pack on cylinder 1. The boat has a history of water/storm damage so corrosion throughout the electrical system is a known issue.




Has anyone experienced this specific misfire pattern on the H5DI? Any tips on testing the coil pack or the signal wire without pulling the intake manifold would be greatly appreciated.




Thanks

[JayG80]

I’d swap the plug and wire with another cylinder and see if the misfire follows. Do you have the diagnostic manual?

https://skidim.com/gcp-4g-diagnostic-manual/

[core-rider]

You’ve already changed the plug so no real reason to swap it. Swap the coil and plug wire to another cylinder and see if the issue follows to the new cylinder. That will easily rule out those parts or not. If no change, then could be wiring going to the coil or maybe an issue with the injector. I’m not real familiar with the DI stuff so diagnostics for it is out of my pay grade.

[Scooter G]

Last time I threw those codes on my '16 G23, I changed out the #1 plug, and was hoping it wasn't the coil pack. I was looking at that project, and as I remember, you have to pull the exhaust manifolds to get to the pack. The code still presented itself. I changed out the other 7 plugs and it went away.
Hmm, maybe just got lucky.

[nathandantzler]

Yes, I'm hoping for the same outcome, I replaced all 8 plugs, but haven't been able to test on the water yet. this is what all 8 plugs looked like.

[mlange]

From the PCM Diagnostic Service Manual

DTC 1311 - Misfire Detected Cylinder #1

SPN - 1323; FMI - 11

• Cylinder #1 Misfire Detected - Driveability/Performance

• Check Condition - Key On, Engine Running

• Fault Condition - Misfire occurrences higher than allowed for each operating condition calibrated at a

level that can result in poor driveability but not necessarily catalyst damage

• Corrective Action(s) - Illuminate MIL and/or sound audible warning or illuminate secondary warning lamp,

disable adaptive learn fueling correction for key-cycle, and disable closed-loop fueling correction during

active fault.

• Emissions related fault


The ECU is capable of detecting combustion misfire for certain crank-cam software modules. The ECU

continuously monitors changes in crankshaft angular velocity, comparing acceleration rates on a cycle-to-cycle

basis and determining if a given cylinder’s rate of change is abnormal compared to other cylinders.

This method of detection is better known as Instant Crank Angle Velocity (ICAV).


Misfire is of concern for four main reasons: 1) damage can occur to after treatment systems due to the

presence of unburned fuel and oxygen causing chemical reactions resulting in extremely high temperatures

causing irreversible damage to catalytic coatings and/or substrates, 2) exhaust emissions increase during

misfiring, 3) the engine’s driveability suffers due to inconsistent operation, and 4) fuel economy suffers due

to the need for higher power operating conditions to achieve the same brake torque. The GCP has two

stages of misfire faults 1) emissions/catalyst damaging misfi re detected and 2) driveability or general misfire

detected.


Emissions/catalyst misfire is generally thought of as a per “bank” fault as multiple cylinders misfiring on the

same bank cumulatively add unburned fuel and oxygen to that banks after treatment device(s). The catalyst/

emissions fault is configured to set based on one or both of the following conditions:

1) After treatment temperatures experienced during this level of misfire are high enough to cause permanent

damage to emission control components

2) Emissions are higher than allowed by legislation due to the presence or misfire.


Therefore, if two cylinders misfire on the same bank together they both may set the misfi e fault even if

neither cylinder individually exceeds the catalyst/misfi re threshold.

Typically the driveability level is calibrated to set prior to the emissions/catalyst level if a two stage fault

is desired. This fault would set to notify the user of a problem prior to it causing damage to the exhaust

after treatment system.


Misfire is typically a result of one or more factors. These factors can include but may not be limited to: 1) a

fouled or damaged spark plug(s), 2) a damaged or defective ignition coil(s) or coil wire(s) resulting in weak

spark generation, 3) a plugged or contaminated injector(s) that intermittently sticks closed resulting in a

lean cylinder charge, 4) an injector(s) that is stuck open causing an uncontrolled rich cylinder charge, 5) low

fuel supply pressure resulting in multiple lean cylinders, 6) low cylinder compression due to a failed or worn

piston ring(s) or non-seating valve(s) can result in a low cylinder pressure charge that may not be ignited,

and 7) an exhaust leak in close proximity to an exhaust valve permitting uncontrolled amounts of oxygen to

be drawn into a cylinder generating an excessively lean charge either directly resulting in misfire or possibly

causing excessive combustion temperatures resulting in burned valves and loss of compression. Misfire

can be difficult to correct as it may be a function of one or more of the conditions mentioned above and may

require checking and/or changing several components for each cylinder or cylinders affected.


This fault sets if the misfire counter for cylinder #1 exceeds the driveability misfire limit set in the misfire

diagnostic calibration and is based on a percentage of misfire over a certain number of engine cycles.



Diagnostic Aids

NOTE: If any other DTCs are present, diagnose those fi rst.

□ Oxygen Sensor Wire - Sensor may be mispositioned contacting the exhaust. Check for short to

ground between harness and sensor and on sensor harness

□ Oil Level- Many engines have valve trains that utilize lifters that are hydraulically actuated and

require specific levels of oil to maintain proper pressure for lifter actuation. If the engine has

improper oil, insufficient oil level, or has too much oil the hydraulic lifters may not function as

intended causing changes in valve lift and timing. As a result, incomplete combustion may

occur as a result of oil problems. Check engine oil level and oil type according to manufacture

maintenance procedures.

□ Spark Plug(s) – Check for fouled or damaged spark plugs. Replace and regap according to

manufacture recommended procedure(s).

□ Spark Plug Wire(s) – Check that spark plug wire is properly connected to ignition coil and

spark plug. If equipped, ensure that spark plug terminal nut is tight to plug and that there is not

substantial wear on nut. Check for cracks in insulation of spark plug wire or boot. Replace spark

plug wire(s) if deemed necessary according to manufacture recommended procedure(s).

□ Fuel Pressure – Check fuel rail pressure at key-on/engine-off or with External Power-All On test

running. Monitor fuel rail pressure when key is turned off to determine if fuel pressure bleeds

down too quickly. Run an injector fi re test on a couple of injectors to monitor the pressure drop in

the rail for each injector. If an injector appears to fl ow inconsistent compared to others, replace

and retest.

□ Cylinder Check – Run a compression test and cylinder leak test on suspected cylinder(s) to check

mechanical integrity of piston rings and valve seats.

□ Exhaust Leak – Pressurize exhaust system with 1-2 psig of air and check for pressure leaks

around exhaust manifold gasket and pre-catalyst EGO sensor. Replace gasket(s) and tighten

fasteners according to manufacture recommended procedure(s).