2001 4x4 LT random misfire, can barley tell at idle. was driving great even with check engine light on.
Now SES light flashes while driving. also noticed the tach jumps a little bit while driving. replaced cap, rotor, plugs, wires a/c delco. replaced all vacum lines to. also replaced crank sensor. mech said he did the relearn. i noticed the oil level also drops when warm at idle, but goes up when i excelerate. so replace oil filter,oil cooler lines, and oil bypass valve.that didnt change a thing. changing the oil sensor tomorrow. motor doesnt over heat and still drives good. can a bad distibutor have anything in common with oil pressure and random misfire? I dont like the flashing SES light. that prob cant be good. already spent way to much

 

also engine seems to be getting plenty of oil and not making any noise. running out of money just chasing probs

 

Several things can cause a P0300, but the most common cause is a fault in secondary ignition, (plugs, wires, cap, rotor and ignition coil). The plugs, cap & rotor need to be AC Delco. Other causes include worn distributor shaft bushings or gear, incorrect camshaft retard adjustment, low fuel pressure, dirty fuel injectors, lazy or dead oxygen sensors, incorrect crankshaft position sensor relearn data, vacuum leaks, etc, etc. These are all basic things that need to be correct. Except for the oxygen sensors, none of them are directly monitored by the PCM. You need to make sure they are all correct before attempting driveability diagnosis. If all that stuff is OK, and it still misfires, the first step is to find out if it's a rich misfire, or a lean misfire, by checking fuel trims on a capable scan tool. If the trims are positive, it's a lean misfire, if the trims are negative, it's a rich misfire. An example of each is: secondary ignition faults will cause negative trims. Low fuel pressure and vacuum leaks will cause positive trims. And just to throw you for a loop, lazy or dead oxygen sensors will cause positive trims, but the engine will be running rich Post the trims and we can help you analyze them. Check short term trim at idle, long term trim at 2000 rpm.


Try to keep your oil pressure posts together in your other threads

 

Freeze Frame Information
Parameter Description
Results

DTC for which Freeze Frame was Stored
P0304

Fuel System 1 Status
Open Loop

Fuel System 2 Status
Open Loop

Calculated LOAD Value
7.45 %

Engine Coolant Temp
89.60 °F

Short Term Fuel Trim - Bank 1
19.53 %

Long Term Fuel Trim - Bank 1
3.91 %


Parameter Description
Results

Short Term Fuel Trim - Bank 2
2.34 %

Long Term Fuel Trim - Bank 2
3.13 %

Intake Manifold Absolute Pressure
10.96 inHg

Engine RPM
1,137.25 rpm

Vehicle Speed Sensor
6.84 mph

Air Flow Rate Mass Air Flow Sensor
1.64 lb/min

Absolute Throttle Position
0.00 %
Monitor Status
Monitor Name
Monitor
Icon
Status

MIL (Check Engine Light)

ON

Misfire Monitoring

Complete

Fuel System Monitoring

Complete

Comprehensive Component Monitoring

Complete

Catalyst Monitoring

Not complete

Heated Catalyst Monitoring

Not Supported

Evaporative System Monitoring

Complete

NMHC Monitoring

Not Supported


Monitor Name
Monitor
Icon
Status

NOxAdsorber Monitoring

Not Supported

Secondary Air System Monitoring

Not complete

Oxygen Sensor Monitoring

Not complete

Oxygen Sensor Heater Monitoring

Complete

EGR System Monitoring

Not complete

Boost Pressure System Monitoring

Not Supported

Exhaust Gas Sensor Monitoring

Not Supported

PM Filter Monitoring

Not Supported

 

Freeze Frame Information
Parameter Description
Results

DTC for which Freeze Frame was Stored
P0304

Fuel System 1 Status
Open Loop

Fuel System 2 Status
Open Loop

Calculated LOAD Value
7.45 %

Engine Coolant Temp
89.60 °F

Short Term Fuel Trim - Bank 1
19.53 %

Long Term Fuel Trim - Bank 1
3.91 %


Parameter Description
Results

Short Term Fuel Trim - Bank 2
2.34 %

Long Term Fuel Trim - Bank 2
3.13 %

Intake Manifold Absolute Pressure
10.96 inHg

Engine RPM
1,137.25 rpm

Vehicle Speed Sensor
6.84 mph

Air Flow Rate Mass Air Flow Sensor
1.64 lb/min

Absolute Throttle Position
0.00 %
Monitor Status
Monitor Name
Monitor
Icon
Status

MIL (Check Engine Light)

ON

Misfire Monitoring

Complete

Fuel System Monitoring

Complete

Comprehensive Component Monitoring

Complete

Catalyst Monitoring

Not complete

Heated Catalyst Monitoring

Not Supported

Evaporative System Monitoring

Complete

NMHC Monitoring

Not Supported


Monitor Name
Monitor
Icon
Status

NOxAdsorber Monitoring

Not Supported

Secondary Air System Monitoring

Not complete

Oxygen Sensor Monitoring

Not complete

Oxygen Sensor Heater Monitoring

Complete

EGR System Monitoring

Not complete

Boost Pressure System Monitoring

Not Supported

Exhaust Gas Sensor Monitoring

Not Supported

PM Filter Monitoring

Not Supported

 

thats the info I just got off my annova 3100g abs canOBD2 Diagnostic tool.
MIL DTC P0304

STORED CODES P0304, P0334

PENDING CODES P0304
Not sure what to do next? please help

 

Both of those were set while in open loop. Oxygen sensor data is ignored by the PCM in open loop because it's unreliable. Short term fuel trim for bank 1 is indicating a lean condition, but it can't be trusted due to the open loop status.


Get some fuel trim numbers when it's in closed loop. Coolant at operating temperature, trans in neutral or park, all accessories turned off, hold rpm steady at ~2000 for a few seconds and mark down long and short term trims for both banks while at 2K rpm.

 

Captain Hook, You are amazing. Thank you for helping me out. I sorry I know you have to be sick of me by now. I have no idea what im doing, but trying to learn. Thank you for all the help. I did like you said and here is what I came up with.

 

That gives us a little more to go on


Bank 1 short term is OK.
Bank 1 long term is indicating that it is running slightly lean.


Bank 2 long and short term are both maxed out trying to lean the mixture out.


We are looking at a seriously rich condition on bank 2. P0304 is a misfire on cylinder #4, which is in bank 2.


Here are some things to test:
Spark plug & wire on #4 cylinder.
Fuel pressure, and especially leakdown.
Cylinder contribution test.
Fuel injector balance test.
Compression test, both wet and dry, on all cylinders.


Also, the MAP sensor is indicating 0" which is obviously incorrect, (it will not run at 1200 rpm with 0" of vacuum). I would suspect a glitch in the scan tool software.

 

a Vacum line was off. So I re tested.. so sorry.
Transmission Diagnostic Trouble Code Information MIL DTC P0304 Cylinder 4 Misfire Detected View Stored Codes P0304 Cylinder 4 Misfire Detected View P0335 Crankshaft Position Sensor Circuit Malfunction View Pending Codes P0304 Cylinder 4 Misfire Detected View Freeze Frame Information
Parameter Description
Results

DTC for which Freeze Frame was Stored
P0304

Fuel System 1 Status
Open Loop

Fuel System 2 Status
Open Loop

Calculated LOAD Value
6.67 %

Engine Coolant Temp
201.20 °F

Short Term Fuel Trim - Bank 1
0.00 %

Long Term Fuel Trim - Bank 1
0.00 %


Parameter Description
Results

Short Term Fuel Trim - Bank 2
0.00 %

Long Term Fuel Trim - Bank 2
0.00 %

Intake Manifold Absolute Pressure
7.40 inHg

Engine RPM
1,650.75 rpm

Vehicle Speed Sensor
0.00 mph

Air Flow Rate Mass Air Flow Sensor
1.41 lb/min

Absolute Throttle Position
3.53 %


Monitor Status
Monitor Name
Monitor
Icon
Status

MIL (Check Engine Light)

ON

Misfire Monitoring

Complete

Fuel System Monitoring

Complete

Comprehensive Component Monitoring

Complete

Catalyst Monitoring

Not complete

Heated Catalyst Monitoring

Not Supported

Evaporative System Monitoring

Not complete

NMHC Monitoring

Not Supported


Monitor Name
Monitor
Icon
Status

NOxAdsorber Monitoring

Not Supported

Secondary Air System Monitoring

Not complete

Oxygen Sensor Monitoring

Not complete

Oxygen Sensor Heater Monitoring

Not complete

EGR System Monitoring

Not complete

Boost Pressure System Monitoring

Not Supported

Exhaust Gas Sensor Monitoring

Not Supported

PM Filter Monitoring

Not Supported