P0300 help
Thread Starter
CF Beginner
Joined: Jan 2018
Posts: 4
Likes: 0
P0300 help
2005 Suburban / 4x4 / 5.3L CID / VIN - Z / no upgrades or mods.
the issue is a p0300 and my scan tool shows misfires on all 8 cylinders.
I did the typical parts toss, replaced plugs and wires, no success.
Randomly the CEL says p0301 so I swapped coil packs with cylinder 3 and still shows p0301.
Compression test shows all cylinders over 155psi.
Long term fuel trim no more than 0-5%
Short term fuel trim no more than 0-5%
Cleaned the throttle body
Cleaned the MAF
Misfire only at idle
I need help
Thank you in advance
the issue is a p0300 and my scan tool shows misfires on all 8 cylinders.
I did the typical parts toss, replaced plugs and wires, no success.
Randomly the CEL says p0301 so I swapped coil packs with cylinder 3 and still shows p0301.
Compression test shows all cylinders over 155psi.
Long term fuel trim no more than 0-5%
Short term fuel trim no more than 0-5%
Cleaned the throttle body
Cleaned the MAF
Misfire only at idle
I need help
Thank you in advance
Thread Starter
CF Beginner
Joined: Jan 2018
Posts: 4
Likes: 0
================================================== =======
Vehicle VIN: 3GNFK16Z25G197571
Vehicle Manufacturer: Chevrolet
Vehicle Calibration ID: 12592618
12594181
1259
Freeze frame information:
------------------
Fuel Status = 0 byte
Engine Load = 34.118 %
Engine Coolant Temperature = 201.2 °F
Fuel Trim Bank 1 Short Term = 0 %
Fuel Trim Bank 1 Long Term = -1.562 %
Fuel Trim Bank 2 Short Term = -3.125 %
Fuel Trim Bank 2 Long Term = 0 %
Intake Manifold Pressure = 6.527 psi
Engine RPM = 739.5 rpm
Speed (OBD) = 3.728 mph
Timing Advance = 17.5 °
Intake Air Temperature = 50 °F
Mass Air Flow Rate = 10.53 g/s
Throttle Position(Manifold) = 17.255 %
End of report.
No misfires while accelerating, only upon deceleration and at idle
yes fuel trim hovers around +/-5%
CF Junior Member
Joined: Apr 2014
Posts: 51
Likes: 0
Misfires on cylinder one high enough to set P0301.
The other cylinder misfires except cylinder eight are low and probably normal.
Since firing order is 1-8, they may be influencing each other or 8 could have actual misfire.
May try swapping 8-6 to see if makes a difference.
Note: reset code and cylinder current/ history counts to get a fresh look.
The P0301 isn't a hard misfire correct? Check engine light doesn't flash?
Since freeze frame shows misfire at light load and cylinder 1 having counts high enough to set P0301 could be injector is over fueling at light loads
Don't know if you can swap injectors.
In addition to very spark isn't leaky to ground you can test by passing a grounded wire along the coil/plug wires to see if attracts spark.
The other cylinder misfires except cylinder eight are low and probably normal.
Since firing order is 1-8, they may be influencing each other or 8 could have actual misfire.
May try swapping 8-6 to see if makes a difference.
Note: reset code and cylinder current/ history counts to get a fresh look.
The P0301 isn't a hard misfire correct? Check engine light doesn't flash?
Since freeze frame shows misfire at light load and cylinder 1 having counts high enough to set P0301 could be injector is over fueling at light loads
Don't know if you can swap injectors.
In addition to very spark isn't leaky to ground you can test by passing a grounded wire along the coil/plug wires to see if attracts spark.
Thread Starter
CF Beginner
Joined: Jan 2018
Posts: 4
Likes: 0
Misfires on cylinder one high enough to set P0301.
The other cylinder misfires except cylinder eight are low and probably normal.
Since firing order is 1-8, they may be influencing each other or 8 could have actual misfire.
May try swapping 8-6 to see if makes a difference.
Note: reset code and cylinder current/ history counts to get a fresh look.
The P0301 isn't a hard misfire correct? Check engine light doesn't flash?
Since freeze frame shows misfire at light load and cylinder 1 having counts high enough to set P0301 could be injector is over fueling at light loads
Don't know if you can swap injectors.
In addition to very spark isn't leaky to ground you can test by passing a grounded wire along the coil/plug wires to see if attracts spark.
The other cylinder misfires except cylinder eight are low and probably normal.
Since firing order is 1-8, they may be influencing each other or 8 could have actual misfire.
May try swapping 8-6 to see if makes a difference.
Note: reset code and cylinder current/ history counts to get a fresh look.
The P0301 isn't a hard misfire correct? Check engine light doesn't flash?
Since freeze frame shows misfire at light load and cylinder 1 having counts high enough to set P0301 could be injector is over fueling at light loads
Don't know if you can swap injectors.
In addition to very spark isn't leaky to ground you can test by passing a grounded wire along the coil/plug wires to see if attracts spark.