Hi all,
I am in upstate NY I have a 2000 Blazer ZR2 4.3 Engine code W, with an NV3500 5 speed. My issue is unique, I have searched for the last couple of months here and elsewhere. I have read the P series help section as well the really long post dealing with the P0300. I have an alldatadiy.com account and an ACTRON CP9580. Now I bought this truck last year and have fixed 23 codes. From secondary air system, EVAP, P series, ETC. My issue is a mild to at times I think the engine is about to explode missfire. It happens with the TPS % is at less than 10. So only when I am maintaing speed at 1800 RPM and up. At first it only did this in the morning when the temp was below 40. Now it does it all the time and the temps have gotten into the 70's. I get a P0300 first thing about 5 miles into my morning drive. By noon I have started and turned off my vehicle three additional times and the code clears itself. To date I have replaced the plugs(checked the gap several times, also not rich or lean) wires, rotor, cap, coil, IC module, Pre CAT, Cat, O2 sensor 3, Air filter, PCV valve, all vacuum lines, all vent lines, EVAP Canister, Fuel Filter, Gas Cap, Purge valve and solenoid, entire secondary air system, alternator, battery and a couple of random relays. I have recked my wires, plugs, rotor, cap, IC and Module. The fuel is clean, the tank is always above half, the fuel pressure is between 59-61. I have 64 Frames of data I recorded and my short term fuel trim peaks at 49 and bottoms at -94.6. Im pretty sure that doesnt sound good but I dont know what it means. I thought the trim was supposed to be between -10 and 10. I can post the Data if someone needs it, I didnt want to take up 10 pages with it. Also The parts I replaced needed to be replaced, I wasnt just throwing money at it. Thanks in advance.

 

What does the ignition advance and knock sensor active count do during this misfire condition? STFT's shouldn't swing that much...

 

I dont think the scanner is capable of checking the knock count. I will check though. It looks like the advance goes up as the trim goes down. Sorry don't know if this is to much or too litle data, I have another 54 frames but its all pretty much the same.
Record Data
FRAME: 0 TM: 0.0
MIL STATUS Off ABSLT TPS(%) 0.0 ENG SPEED(RPM) 989 CALC LOAD(%) 5.5 MAF(LB/M) 1.26 MAP("HG) 9.7 COOLANT(°F) 106 IAT(°F) 73 IGN ADV(°) 5.5 SECOND AIR UPSTR ST FTRM1(%) 0.0 LT FTRM1(%) 3.1 ST FTRM2(%) 0.0 LT FTRM2(%) 3.1 VEH SPEED(MPH) 0 FUEL SYS 1 OPEN FUEL SYS 2 OPEN O2S11(V) 0.125 ST FTRM11(%) -80.5 O2S13(V) 0.160 O2S21(V) 0.180 ST FTRM21(%) -71.9 PTO STATUS Dise OBD2 STAT CA
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FRAME: 1 TM: 2.5
MIL STATUS Off ABSLT TPS(%) 0.0 ENG SPEED(RPM) 974 CALC LOAD(%) 5.5 MAF(LB/M) 1.25 MAP("HG) 9.7 COOLANT(°F) 106 IAT(°F) 73 IGN ADV(°) 4.5 SECOND AIR UPSTR
ST FTRM1(%) 0.0 LT FTRM1(%) 3.1 ST FTRM2(%) 0.0 LT FTRM2(%) 3.1 VEH SPEED(MPH) 0 FUEL SYS 1 OPEN FUEL SYS 2 OPEN O2S11(V) 0.120 ST FTRM11(%) -82.0 O2S13(V) 0.160 O2S21(V) 0.160 ST FTRM21(%) -74.2 PTO STATUS Dise OBD2 STAT CA
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FRAME: 2 TM: 4.9
MIL STATUS Off ABSLT TPS(%) 0.0 ENG SPEED(RPM) 980 CALC LOAD(%) 5.5 MAF(LB/M) 1.25 MAP("HG) 9.7 COOLANT(°F) 106 IAT(°F) 73 IGN ADV(°) 4.0 SECOND AIR UPSTR ST FTRM1(%) 0.0 LT FTRM1(%) 3.1 ST FTRM2(%) 0.0 LT FTRM2(%) 3.1 VEH SPEED(MPH) 0 FUEL SYS 1 OPEN FUEL SYS 2 OPEN O2S11(V) 0.125 ST FTRM11(%) -81.3 O2S13(V) 0.150 O2S21(V) 0.165 ST FTRM21(%) -75.0 PTO STATUS Dise OBD2 STAT CA
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FRAME: 3 TM: 7.4
MIL STATUS Off ABSLT TPS(%) 0.0 ENG SPEED(RPM) 976 CALC LOAD(%) 5.5 MAF(LB/M) 1.25 MAP("HG) 10.3 COOLANT(°F) 108 IAT(°F) 73 IGN ADV(°) 1.5 SECOND AIR UPSTR ST FTRM1(%) 0.0 LT FTRM1(%) 3.1 ST FTRM2(%) 0.0 LT FTRM2(%) 7.0 VEH SPEED(MPH) 0 FUEL SYS 1 OPEN FUEL SYS 2 OPEN O2S11(V) 0.960 ST FTRM11(%) 49.2 O2S13(V) 0.975 O2S21(V) 0.300 ST FTRM21(%) 39.1 PTO STATUS Dise OBD2 STAT CA
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FRAME: 4 TM: 10.0
MIL STATUS Off ABSLT TPS(%) 0.0 ENG SPEED(RPM) 2038 CALC LOAD(%) 5.9 MAF(LB/M) 1.25 MAP("HG) 5.9 COOLANT(°F) 108 IAT(°F) 73 IGN ADV(°) 0.0 SECOND AIR UPSTR ST FTRM1(%) 0.0 LT FTRM1(%) 3.1 ST FTRM2(%) 0.0 LT FTRM2(%) 3.1 VEH SPEED(MPH) 0
FUEL SYS 1 OPEN FUEL SYS 2 OPEN O2S11(V) 0.885 ST FTRM11(%) 33.6 O2S13(V) 0.225 O2S21(V) 0.930 ST FTRM21(%) 43.8 PTO STATUS Dise OBD2 STAT CA
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FRAME: 5 TM: 12.7
MIL STATUS Off ABSLT TPS(%) 0.0 ENG SPEED(RPM) 936 CALC LOAD(%) 4.7 MAF(LB/M) 1.11 MAP("HG) 9.7 COOLANT(°F) 108 IAT(°F) 73 IGN ADV(°) 6.5 SECOND AIR ATMOS ST FTRM1(%) 0.8 LT FTRM1(%) 3.1 ST FTRM2(%) 0.8 LT FTRM2(%) 3.1 VEH SPEED(MPH) 0 FUEL SYS 1 OPEN FUEL SYS 2 OPEN O2S11(V) 0.825 ST FTRM11(%) 32.0 O2S13(V) 0.195 O2S21(V) 0.330 ST FTRM21(%) -57.8 PTO STATUS Dise OBD2 STAT CA
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FRAME: 6 TM: 15.4
MIL STATUS Off ABSLT TPS(%) 0.0 ENG SPEED(RPM) 945
CALC LOAD(%) 5.1 MAF(LB/M) 1.14 MAP("HG) 9.7 COOLANT(°F) 108 IAT(°F) 73 IGN ADV(°) 6.5 SECOND AIR ATMOS ST FTRM1(%) 0.8 LT FTRM1(%) 3.1 ST FTRM2(%) 3.1 LT FTRM2(%) 3.1 VEH SPEED(MPH) 0 FUEL SYS 1 OPEN FUEL SYS 2 OPEN O2S11(V) 0.845 ST FTRM11(%) 32.8 O2S13(V) 0.165 O2S21(V) 0.860 ST FTRM21(%) 13.3 PTO STATUS Dise OBD2 STAT CA
---------------------
FRAME: 7 TM: 18.1
MIL STATUS Off ABSLT TPS(%) 0.0 ENG SPEED(RPM) 963 CALC LOAD(%) 5.1 MAF(LB/M) 1.15 MAP("HG) 9.7 COOLANT(°F) 108 IAT(°F) 73 IGN ADV(°) 6.0 SECOND AIR ATMOS ST FTRM1(%) 1.6 LT FTRM1(%) 3.1 ST FTRM2(%) 2.3 LT FTRM2(%) 3.1 VEH SPEED(MPH) 0 FUEL SYS 1 OPEN FUEL SYS 2 OPEN O2S11(V) 0.825 ST FTRM11(%) 30.5 O2S13(V) 0.165
O2S21(V) 0.235 ST FTRM21(%) -65.6 PTO STATUS Dise OBD2 STAT CA
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FRAME: 8 TM: 21.0
MIL STATUS Off ABSLT TPS(%) 0.0 ENG SPEED(RPM) 971 CALC LOAD(%) 5.1 MAF(LB/M) 1.82 MAP("HG) 11.8 COOLANT(°F) 111 IAT(°F) 73 IGN ADV(°) 17.5 SECOND AIR ATMOS ST FTRM1(%) 3.1 LT FTRM1(%) 6.3 ST FTRM2(%) 3.9 LT FTRM2(%) 7.0 VEH SPEED(MPH) 0 FUEL SYS 1 OPEN FUEL SYS 2 OPEN O2S11(V) 0.880 ST FTRM11(%) 39.1 O2S13(V) 0.880 O2S21(V) 0.930 ST FTRM21(%) 45.3 PTO STATUS Dise OBD2 STAT CA
---------------------
FRAME: 9 TM: 24.1
MIL STATUS Off ABSLT TPS(%) 3.1 ENG SPEED(RPM) 1227 CALC LOAD(%) 9.0 MAF(LB/M) 2.03 MAP("HG) 11.5 COOLANT(°F) 111 IAT(°F) 70
IGN ADV(°) 18.5 SECOND AIR ATMOS ST FTRM1(%) 0.8 LT FTRM1(%) 6.3 ST FTRM2(%) -2.3 LT FTRM2(%) 7.0 VEH SPEED(MPH) 2 FUEL SYS 1 OPEN FUEL SYS 2 OPEN O2S11(V) 0.925 ST FTRM11(%) 44.5 O2S13(V) 0.865 O2S21(V) 0.955 ST FTRM21(%) 46.9 PTO STATUS Dise OBD2 STAT CA
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FRAME: 10 TM: 26.9
MIL STATUS Off ABSLT TPS(%) 0.0 ENG SPEED(RPM) 899 CALC LOAD(%) 5.1 MAF(LB/M) 1.16 MAP("HG) 10.6 COOLANT(°F) 111 IAT(°F) 70 IGN ADV(°) 5.0 SECOND AIR ATMOS ST FTRM1(%) -3.9 LT FTRM1(%) 3.1 ST FTRM2(%) -5.5 LT FTRM2(%) 3.1 VEH SPEED(MPH) 0 FUEL SYS 1 OPEN FUEL SYS 2 OPEN O2S11(V) 0.055 ST FTRM11(%) -91.4 O2S13(V) 0.130 O2S21(V) 0.110 ST FTRM21(%) -83.6 PTO STATUS Dise OBD2 STAT CA

 

You have to watch the data as it is coming in. Freeze frame data really doesn't tell you a whole lot, IMO. You can ignore FTRM11 & FTRM21 values. What you need to watch are the FTRM1 & FTRM2 values.