Cylinder misfire spark
how many miles on the odometer, mines 95k.
ah a v6, P0306 is #6 misfiring. 2.5L V6
300 is all 6 misfiring.... oops.
it is. for sure.
misfire is cause by many things, only 3 in physics, but many real world. (compression + spark +fuel rates)
i works this easy, way.
i have a full scan tool not just a code reader (near useless it)
i make sure my V6 (I have an 04) holds closed loop at idle and 2500 rpm. i f not , fix that first.
easy, it is. just look, bingo, Open loop, (out of control)
fueling is out of control.
but, first i do that tune up. in the manual, 60k , 120k, 180k, see?
do that first. , spark plugs dont last foreever nor filters.
then i replace both front 02 sensors at 100k miles. there design life.
V6 has 2 front sensors. (rear can , just sit and be ignored)
if it misfires. now, i toss a coin.
compression or fuel pressure.
i can do both in 30min flat but i toss coin lands on fuel.
i check fuel pressure and its.
60psi, fuel regulator is bad,
20psi, same, or bad pump or bad 12vdc to pump, 8v to pump is bad wiring.
one thing that helps is to find out if the engine is running too rich or too lean.
and if there are cracks in the exhuast near the 02 sensors.
i force the EFI rich and lean watching both 02 sensors in my scan tool
to see if i can force them lean or rich.
on the v6, we can introduce air leaks, to the plenum.
this will cause lean, and the o2 most react to my lean forcing
or its dead.
i can force richer, if i suspect lean or 02 shows lean, by
removing the Fuel pump regulator hose (vac) and plugging hose fast.
this causes the FPreg to go to high pressure. max.
i watch the 02 and see it go rich, if not the 02 is bad or you have exhaust leaks, or dead cylinder causing the 02 to fib.
you have 2 banks, and both banks are running off 1 MAF
so you can look at both 02 sensors (front) B1S1 and B1S2
and see if both react the same. to my forcing's.
i dont think you have 3 bad cops out 6. no.
if any cylinder misfires on bank one, then bank 1 o2 goes nuts
same with the Bank 2. this can aid troubleshooting having 2 banks.
the MAF can not lie for 1 cyclinder nor one bank
the 02s can lie for each bank,
both are key to diagnosis.
let me give an example say
injector 1 leaks.
this is your lay out.
my guess is its not lost compression (no test guess, mostly useless)
not 2 bad cops one on each side will cause 300s
not one bad cop. as other side would be ok.
not one bad injector.
my guess, is fuel pressure is way off.
or maf running lean (dirty, spary clean it 12inches away not close)
low fuel pressure
too high fuel pressure.
all comments are for engine with 60k mile service done,
60k, 12ok, etc.
Jan 13, 2014 |
2002 Suzuki Grand Vitara