misfire. 101 (only under load,) did you know spark plugs that are really bad , always fail under load (high cylinder pressures, do that) This can be demonstrated in old days we had a tester that did that test, to prove to tight wad customers (1960s we had it), see, your plug here fail. see it misfire in this nice DELCO tester?(bench)
we have spark plugs here (oem stock) sold in stores here, for $1.49 cents. its called a no-brainer tuneup, harmless , easy fast and can be magic. (by not means fixes them all)
bullet list.
code 12s while it misfires? and while driving, do know that you can drive for a week, with 12s flashing , with no harm at all.
after all it might pop a code from CMP? be super important to know that for sure.
misfire has over 50 causes. (parts bad and more) but in Physics pure far less and even less doing 1 to 10 tests.
is car a daily driver.?
was it a BARN FIND? parked for years.
or just old "Nelly Bell", that is the farm used, stump puller.? only.
or a trailer-ed only , offroad only machine, that sits all winter in a garage?
ever do the 60k mile (repeats) full tune up in the last decade? if no ,why delay this?
misfire pure physics we do tools way more easy, (scanners , 3 gauges, and tools, meters etc)
misfire 101:
1-bad fuel
2-never ever tuned up, spark parts, air /fuel filters.?
3-the EFI is is not getting full 12vdc power all the time (bad wiring to power source battery, called 12vdc power drop out, and cuts spark dead in 1 nanosecond fast. instantly.
4: engine compression low, x4 , or the crank pulley never torque to 17mm large bolt at 94ft/lbs (or 128-N/M) and the crank snot is now wrecked
5: Spark failing, plugs , HV wire set bad, cap , rotor? see #2.
6: bad fueling (called high AFR) , flooding, and spark tips black? fuel pressure wrong, 02 bad.?
7: TPS bad causing Tip -in acceleration lean outs and misfire.? will do it, car moving at any time right foot moves.
8: weak maf, or air leaks past it making it read wrong. clean the hot wire from 150mm distant, using maf cleaner safe for plastics. only.
9: air leaks to the engine Plenum , will go lean and bog or feel like its starving for fuel, vacuum leaks small are corrected by working 02 , larger are not and goes lean on all vacuum leaks.
10: scans show the 02 sensor (Front) is stuck? exhaust leaks near it , is hopeless.
11; low fuel pressure, it must be at spec, and the FPR tests must all pass, (vacuum over fuel pressure bar tests) if not the FPR IS BAD. most now are failing BTW. to old to be any good.
12: the main AIR intake on our 16v has this huge pipe that an leak air. seen them crack or seals there fail. lots. it must not be allowed to leak. air.(suck air from non maf end)
13: A WONKY CMP , cam sensor , never fails on ours. ever. but the wires to it x10 more likely. bad wiring, to all EFI parts same deal. HALL Sensors RULE !
that it. hope it helps in some small way.
good luck.
we have spark plugs here (oem stock) sold in stores here, for $1.49 cents. its called a no-brainer tuneup, harmless , easy fast and can be magic. (by not means fixes them all)
bullet list.
code 12s while it misfires? and while driving, do know that you can drive for a week, with 12s flashing , with no harm at all.
after all it might pop a code from CMP? be super important to know that for sure.
misfire has over 50 causes. (parts bad and more) but in Physics pure far less and even less doing 1 to 10 tests.
is car a daily driver.?
was it a BARN FIND? parked for years.
or just old "Nelly Bell", that is the farm used, stump puller.? only.
or a trailer-ed only , offroad only machine, that sits all winter in a garage?
ever do the 60k mile (repeats) full tune up in the last decade? if no ,why delay this?
misfire pure physics we do tools way more easy, (scanners , 3 gauges, and tools, meters etc)
misfire 101:
1-bad fuel
2-never ever tuned up, spark parts, air /fuel filters.?
3-the EFI is is not getting full 12vdc power all the time (bad wiring to power source battery, called 12vdc power drop out, and cuts spark dead in 1 nanosecond fast. instantly.
4: engine compression low, x4 , or the crank pulley never torque to 17mm large bolt at 94ft/lbs (or 128-N/M) and the crank snot is now wrecked
5: Spark failing, plugs , HV wire set bad, cap , rotor? see #2.
6: bad fueling (called high AFR) , flooding, and spark tips black? fuel pressure wrong, 02 bad.?
7: TPS bad causing Tip -in acceleration lean outs and misfire.? will do it, car moving at any time right foot moves.
8: weak maf, or air leaks past it making it read wrong. clean the hot wire from 150mm distant, using maf cleaner safe for plastics. only.
9: air leaks to the engine Plenum , will go lean and bog or feel like its starving for fuel, vacuum leaks small are corrected by working 02 , larger are not and goes lean on all vacuum leaks.
10: scans show the 02 sensor (Front) is stuck? exhaust leaks near it , is hopeless.
11; low fuel pressure, it must be at spec, and the FPR tests must all pass, (vacuum over fuel pressure bar tests) if not the FPR IS BAD. most now are failing BTW. to old to be any good.
12: the main AIR intake on our 16v has this huge pipe that an leak air. seen them crack or seals there fail. lots. it must not be allowed to leak. air.(suck air from non maf end)
13: A WONKY CMP , cam sensor , never fails on ours. ever. but the wires to it x10 more likely. bad wiring, to all EFI parts same deal. HALL Sensors RULE !
that it. hope it helps in some small way.
good luck.
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