p0300 help

[Gregs]

hey guys i'm having a little trouble with my truck. Leaving a parking lot the truck starts sounding weird and the check engine light comes on. It starts shuddering and the check engine light is flashing so i know that its misfiring. i wasn't able to get up over 20 mph so i pulled to the side of the road. everything looked ok so i started it up again and drive home without any problems. Scanned it and all it has is p0300. watching misfires at idle i have about 4 per cylinder that go away if i make the engine idle up. i'm thinking the misfires at idle are because of my cam. it doesn't have cats so its not like that could be the problem. What do you guys think? I didn't have my v2 with me so i didn't get anything caught on a log. plugs and wires are pretty new and fpr is ok. thinking possible fuel injector hung up? freeze frame showed stft bank 1 at -25 and ltft bank 1 were -3 when the code set. bank 1 is an lc1 simulated nb

i also checked crank angle sensor cal and it was ok

[joecar]

The LTFT at -25% indicates there is too much fuel if the fuel was being burnt properly...

if the fuel was not being burnt properly (as in a misfire) then the NBO2 would see excess oxygen and would cause the PCM to drive the LTFT grossly positive;

so we can say that there is too much fuel on that bank...

[ assuming it is the truck in your sig, it would have a manifold referenced FPR ]

check these:
- remove reference hose from FPR and check for fuel in the hose or fuel coming out of the FPR (if it is then FPR is bad);
- with referenced FPR, rail pressure should vary as MAP or MANVAC vary (i.e. measured rail pressure minus MAP should yield a constant);
- key on engine off (cycle key several times to prime fuel rail), you should see rail pressure maintain steady (if not, the something leaks: injector(s) or FPR).

It's on one bank so it probably isn't FPR... it maybe leaky injector(s) on that bank.

Of course, check plug wires, coils; also check for loss of coolant and do pressure test on cooling system;

how old are the NBO2 sensor(s)...?

[Gregs]

The LTFT at -25% indicates there is too much fuel if the fuel was being burnt properly...

if the fuel was not being burnt properly (as in a misfire) then the NBO2 would see excess oxygen and would cause the PCM to drive the LTFT grossly positive;

so we can say that there is too much fuel on that bank...

[ assuming it is the truck in your sig, it would have a manifold referenced FPR ]

check these:
- remove reference hose from FPR and check for fuel in the hose or fuel coming out of the FPR (if it is then FPR is bad);
- with referenced FPR, rail pressure should vary as MAP or MANVAC vary (i.e. measured rail pressure minus MAP should yield a constant);
- key on engine off (cycle key several times to prime fuel rail), you should see rail pressure maintain steady (if not, the something leaks: injector(s) or FPR).

It's on one bank so it probably isn't FPR... it maybe leaky injector(s) on that bank.

Of course, check plug wires, coils; also check for loss of coolant and do pressure test on cooling system;

how old are the NBO2 sensor(s)...?

yeah i checked the fpr and its fine, bank 1 is a wideband if that matters. wires and plugs are very new. will do a coolant pressure test tonight at work, but i'm not missing any coolant.

the freeze frame only showed
bank 2 stft = -3
bank 2 ltft = -3
bank 1 stft = -25
bank 1 ltft = -3

it runs ok right now. i was thinking that since only bank 1 was very rich that an injector was bad on that side but if it were one bad injector i shouldn't have gotten a random misfire right? shouldn't it have been cylinder specific?

[joecar]

Check also your ground connections.

[nevinsb]

It runs fine with STFT disabled? Looks like you got a 266 cam in there, which isn't all that hot of a cam. Could also be a valve train failure.

[Gregs]

i had the code pop up again, i didn't feel the truck misfire but i saw the light turn on. I got a freeze frame shot and i was scanning when the light turned on. I'm very confused because i don't see anything grossly wrong. Help!


[PCM INFO]
VIN=2GCEK19T531248207
OS=12579405
Stream=LS1B

[PCM CVN]
12579405=A583
12577861=D700
12579437=23F6
12572447=FFD4
12570845=7739
12578354=82D4
12572573=78D8
12572533=C012

[System Readiness Tests]
MIL=ON
DTC_CNT=1
MIS=Ready
FUEL=Ready
CCM=Ready
CAT=Pending
HCAT=N/A
EVAP=Pending
AIR=N/A
ACRF=N/A
O2S=Pending
HTR=Ready
EGR=N/A

[DTCs EPA Current]
P0300=PCM,--------

[DTCs EPA Pending]
P0300=PCM,--------

[DTCs Enhanced]
P0300=PCM,MF-HX--I

[PCM Freeze Frame 0]
<0002>=0x0300
FUELSYS.FUELSYS1=CL
FUELSYS.FUELSYS2=CL
LOAD_PCT=10.2%
ECT=91°C
SHRTFT1=0.8%
LONGFT1=-2.3%
SHRTFT2=7.0%
LONGFT2=0.0%
MAP=54kPa
RPM=1434rpm
VSS=16kmh
MAF=25.3g/s
TP=21.2%
STATE02.TCCPWM=Inactive
STATE02.EBPSW=Inactive
STATE02.LD=Inactive
STATE02.CBPSW=Inactive
STATE02.TCCSOL=Inactive
STATE02.VATFD=Inactive
STATE02.TRACSTAT=Inactive
EGRS=0.000V
FTEMP=63°C
FTPS=1.647V
EGR=0.0%
ECT1ST=86°C
IDLEDES=5rpm
EGRDES=0.0%
BARO_B=98.9kPa
<119E>=0x92
RUNTIME=29600s
MFCSTAT.MFC2ND=None
MFCSTAT.MFC1ST=None
ODOFIRST=15km
ODOLAST=15km
FFCOUNT=1Count
FFPASS=0Count
FFNOTRUN=0Count
IBPW1=5.7ms
IBPW2=6.2ms
ETCPED=5.9%
ETCTP=21.6%
E85PCT=0.0%
TPDES=22.0%
APP=19.9%
<139C>=0x00
<139D>=0x0000
TSTATE33.GEAR_X=No
TSTATE33.GEAR_P=No
TSTATE33.GEAR_R=No
TSTATE33.GEAR_N=No
TSTATE33.GEAR_D=No
TSTATE33.GEAR_3=No
TSTATE33.GEAR_2=No
TSTATE33.GEAR_1=No
TOS=409rpm
GEAR=Second
<0002>=0x0300

[PCM Freeze Frame 1]
<0002>=0x0300
FUELSYS.FUELSYS1=CL
FUELSYS.FUELSYS2=CL
LOAD_PCT=10.2%
ECT=91°C
SHRTFT1=0.8%
LONGFT1=-2.3%
SHRTFT2=7.0%
LONGFT2=0.0%
MAP=54kPa
RPM=1434rpm
VSS=16kmh
MAF=25.3g/s
TP=21.2%
STATE02.TCCPWM=Inactive
STATE02.EBPSW=Inactive
STATE02.LD=Inactive
STATE02.CBPSW=Inactive
STATE02.TCCSOL=Inactive
STATE02.VATFD=Inactive
STATE02.TRACSTAT=Inactive
EGRS=0.000V
FTEMP=63°C
FTPS=1.647V
EGR=0.0%
ECT1ST=86°C
IDLEDES=5rpm
EGRDES=0.0%
BARO_B=98.9kPa
<119E>=0x92
RUNTIME=29600s
MFCSTAT.MFC2ND=None
MFCSTAT.MFC1ST=None
ODOFIRST=15km
ODOLAST=15km
FFCOUNT=1Count
FFPASS=0Count
FFNOTRUN=0Count
IBPW1=5.7ms
IBPW2=6.2ms
ETCPED=5.9%
ETCTP=21.6%
E85PCT=0.0%
TPDES=22.0%
APP=19.9%
<139C>=0x00
<139D>=0x0000
TSTATE33.GEAR_X=No
TSTATE33.GEAR_P=No
TSTATE33.GEAR_R=No
TSTATE33.GEAR_N=No
TSTATE33.GEAR_D=No
TSTATE33.GEAR_3=No
TSTATE33.GEAR_2=No
TSTATE33.GEAR_1=No
TOS=409rpm
GEAR=Second
<0002>=0x0300

[PCM Freeze Frame 2]
; Freeze Frame Empty.

[PCM Freeze Frame 3]
; Freeze Frame Empty.

[PCM Freeze Frame 4]
; Freeze Frame Empty.

[PCM Freeze Frame 5]
; Freeze Frame Empty.

[MODE05]
; Mode $05 data could not be retrieved.

[MODE06]
;ID MinLimit Value MaxLimit Units Result
;----- -------- -------- -------- -------- ------
0204.L= 0, 0, -, ,OK ,"EVAP Canister Loading Test"
0266.H= -, 1.3, 7.0,inH2Ov ,OK ,"EVAP Excess Vacuum Test 1"
0236.H= -, 0.0, 0.0,s ,OK ,"EVAP Excess Vacuum Fail Test 2"
0206.L= 0.0, 0.0, -,int-s ,OK ,"EVAP Excess Vacuum Pass Test 2"
0250.L= 11.0, 1.5, -,inH2Ov ,LOW ,"EVAP Weak Vacuum Pass Test 1"
0260.H= -, 35.0, 35.0,int-s ,OK ,"EVAP Weak Vacuum Fail Test 1"
0230.L= 0.0, 0.0, -,s ,OK ,"EVAP Weak Vacuum Test 2 Vacuum"
0240.L= 0.0, 0.0, -,s ,OK ,"EVAP Weak Vacuum Test 2 Vapor"
0211.L= 0.0, 0.0, -,s ,OK ,"EVAP Purge Leak Pass Test"
0221.H= -, 0, 0,s ,OK ,"EVAP Purge Leak Vapor Fail Test"
0271.H= -, 0.0, 0.0,inH2Ov ,OK ,"EVAP Purge Leak Vacuum Fail Test"
050A.H= -, 461, 1450,Samples ,OK ,"Post Catalyst Sensor Open Test - B1S2"
054A.H= -, 0, 1450,Samples ,OK ,"Post Catalyst Sensor Open Test - B2S2"
0A09.H= -, 0.000, 0.000,:1 ,OK ,"EONV NV .020},Test"
0C60.H= -, 0.000, 0.035,s ,OK ,"Catalyst Test Bank 1 (Using OSC Compensation Units)"
0C70.H= -, 0.000, 0.030,s ,OK ,"Catalyst Test Bank 2 (Using OSC Compensation Units)"
0E11.H= -, 9, 8,Samples ,HIGH ,"Oxygen Sensor Heater X/Y Samples Test - B1S1"
0E12.H= -, 9, 8,Samples ,HIGH ,"Oxygen Sensor Heater X/Y Samples Test - B1S2"
0E21.H= -, 0, 8,Samples ,OK ,"Oxygen Sensor Heater X/Y Samples Test - B2S1"
0E22.H= -, 9, 8,Samples ,HIGH ,"Oxygen Sensor Heater X/Y Samples Test - B2S2"

[Gregs]

Tested fuel pressure and its good, injectors ohmed out good, pressure tested coolant and it was good, and chemical block tested it and it was good too

[Motorzane]

Check for a vacuum leak. Possible intake gasket.

[Gregs]

Tested intake gaskets and ther're good. Engine compression is also good. I dont know where to go from here

[joecar]

What is rail pressure with reference hose removed...?

What is rail pressure with reference hose attached (subtract MAP from this, do you get the same value as above...?)...?

Check spark plugs and wires again... is the ground connection at the rear of the driver side head good and connected...?

Check that each coil body has zero volts compared to engine block (i.e. are coils grounded good)...?

Check coils for cracks or external carbon tracking.

Check that wires click onto plugs and into coils securely.

Does it get worse with heat...?