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+--- Thread: X15 misfire codes 1, 2, 3 (/showthread.php?tid=10092)
X15 misfire codes 1, 2, 3 - Dieseltech53 - 04-27-2025
I have an x15 565 on a diet that keeps throwing misfire codes (attached) cause unknown after driving for cylinders 1,2,3. Won't throw them while idling. Have replaced exhaust gas pressure sensor, injector harness (due to oil in the plug), updated ecm calibration, tried wiggling the harness to see if codes come up, as well as moving injectors with no change. I also has a new head that was put on last fall. It passes injector performance tests. But struggling to find anyone around me with the capability to test injectors. Trying to figure out what my next move should be between getting injectors tested, removing head to inspect valves, or something I'm missing. It started as just cylinder 2 and now has moved to 1 and 3 as well.
RE: X15 misfire codes 1, 2, 3 - Rawze - 04-28-2025
Misfire detection is done via the exhaust gas pressure sensor and its circuit. If the sensor is not OEM brand (purchased at a stealers$it or from cummins themselves), then it will cause ghost mis-fire codes. Dorman, chineesium, and other non oem brands of sensors are notorious for this.
Remove the exhaust gas pressure sensor (exh. manifold pressure sensor) .. and clean out the passageway thru the thermostat housing + the little pipe that goes between the exhaust manifold and the thermostat housing that feeds it. Also ensure you have an OEM-only sensor in there too.
... And ... de-mandate programming can cause issues like this too,.. so if I have not reviewed the program then that is also the place to start. Copy the file out of the ecm and e-mail it to me .. I will review it and tell you exactly what someone did in there.
RE: X15 misfire codes 1, 2, 3 - Dieseltech53 - 04-28-2025
The sensor I got right from cummins. I will try cleaning the tube but I could feel vacuum on the port when it was running so did not assume it was plugged.
RE: X15 misfire codes 1, 2, 3 - Rawze - 04-28-2025
(04-28-2025 )Dieseltech53 Wrote: The sensor I got right from cummins. I will try cleaning the tube but I could feel vacuum on the port when it was running so did not assume it was plugged.
There should be no vacuum at the exhaust manifold pressure sensor port.
I think your missing some relevant info there ... The exhaust man sensor is not only measuring pressure ... but also 'listening' to the sound waves/pulses (popping sound) from each of the cylinders as each exhaust valves open (hence the mis-fire detection). That passage tends to clog or get partially clogged ... throwing off the sounds into the sensor, so it needs to stay clean ... and its notorious for getting dirty over time or the pipe at the manifold getting loose/cracked, etc.
RE: X15 misfire codes 1, 2, 3 - Dieseltech53 - 04-28-2025
I pulled the tube off it was almost spotless. Where the tube goes in the thermostat housing was blocked by some soot. Took brake cleaner and a piece of wire and cleaned it out. Reset injectors and is running great now. Should've checked that sooner. Thanks for your help!