Random Misfire

(_P1300_) or (_P0301 through P0304_)
The scan tool indicates Diagnostic Trouble Code (DTC) P1300 or some of P0301 - P0304: Random misfire.

Description
Misfire detection is accomplished by monitoring the crankshaft speed with the crankshaft speed fluctuation sensor which is attached to the crankshaft.
If misfiring strong enough to damage the catalyst is detected, the MIL will blink during the time of its occurrence, and DTC P1300 or some of DTCs PO3Ol through P0304 will be stored. Then, after misfire has ceased, the MIL will come on.
If misfiring that increases emissions is detected during two consecutive driving cycles, the MIL will come on, and DTC P1300 or some of DTCs P0301 through P0304 will be stored.

NOTE:
- If some of the DTCs listed below are stored at the same time as a misfire DTC, troubleshoot those DTCs first, then troubleshoot the misfire DTC.

P0106 - MAP sensor
P0171, P0172 - Fuel metering
P0505 - Idle Control System
P1361, P1362 - TDC sensor
P1381, P1382 - CYP sensor
P1508 - IAC valve

Possible Cause
- Fuel pump insufficient fuel pressure, amount of flow
- Fuel line clogging, blockage, leakage
- Fuel filter clogging
- Fuel pressure regulator stuck open
- Distributor malfunction
- Ignition coil wire open, leakage
- Ignition control module malfunction
- MAP sensor range/performance, poor response
- Valves carbon deposit
- Compression low
- IAC valve malfunction
- Fast idle thermo valve malfunction
- Fuel does not meet Owner's Manual spec., lack of fuel
- VTEC system malfunction

Troubleshooting
By test-driving, determine the conditions during which misfire occurs. Depending on these conditions, test in the order described in the table below.

NOTE:
- If misfire doesn't recur, some possible causes are fuel that doesn't meet Owner's manual spec, lack of fuel, carbon deposits on spark plug, etc.