Cold Start misfire Civic SI

[jeff smith]

Good Morning community,
I need some assistance troubleshooting an intermittent misfire on a 2014 honda civic si 115,000miles code P0301.
Misfire happens early in the cold start, changed spark plugs and swapped the cold pack, it takes about 2 weeks for the code to pop up after i clear it. Here’s a freeze frame for the pros.
Any help will be greatly appreciated.

DTC that caused required freeze frame data storage P0301
Fuel system 1 status CL
Fuel System 2 status —
Calculated Load Value 25.5 %
Engine Coolant Temperature 31 °C
Short Term Fuel Trim -Bank 1 -7.0 %
Long Term Fuel Trim – Bank 1 -0.8 %
Intake Manifold Absolute Pressure 38.0 kPa
Engine RPM 1482 rpm
Vehicle Speed Sensor 8 km/h
Ignition Timing Advance for #1 Cylinder 19.0 °
Intake Air Temperature 16 °C
Air Flow Rate from Mass Air Flow Sensor 7.37 g/s
Absolute Throttle Position 16.5 %
Time Since Engine Start 40 sec
Commanded Evaporative Purge 0.0 %
Fuel Level Input 65.9 %
Barometric Pressure 101 kPa
Control module voltage 12.225 V
1
Absolute Load Value 21.6 %
Commanded Equivalence Ratio 0.999
Relative Throttle Position 6.7 %
Absolute Throttle Position B 33.3 %
Accelerator Pedal Position D 18.8 %
Accelerator Pedal Position E 9.4 %
Commanded Throttle Actuator Control 7.5 %
Type of fuel currently being utilized by the vehicle GAS

Topic

[Richard Kirshy]

If the miss fire is consistent on cold startups.
Might try testing for vacuum leak on the intake

[jeff smith]

Yea I will try the propane test.

[Bang Klas]

By the way, do not forget that the air intake is also selected based on the brand of engine. That is why it is necessary to choose it very carefully, so that there would not be any complaints and comments about the fact that it is somehow crooked and so on. For example, I read about Best Cold Air Intake For 6.0 Vortec https://boostyourengine.com/cold-air-intake-for-6-0-vortec/ and it helped me to decide when I needed an air intake, which was exactly what I needed. So keep your eyes open.

[Billy]

Swap injectors with another cylinder, then compression and leakdown. Any coolant loss?

[jeff smith]

Update. So I swapped injectors. Issues came back. But since its been warm the issue hasnt came back in a week. I will keep my eye out but no coolant leaks. Car is completely stock.

New issue is that after I get off the throttle the car goes into Open Loop Drive and lunges me forward for a second. It might be a throttle position sensor issue because I did open the thottle body flap and wiped it down. Tired to relearn the thottle body but issue is still there. Might have to buy a new thottle body

[Author]

Replies