Replaced spark plugs,replaced injector #5 cyl, switched plug wires between different cylinders and miss did not move with wires. Switched plug wires on coil between cyl 2 & 5 but miss did not move. have 170 lbs compresion. no abnormal engine noise. Sets code P0300 and scan tool shows #5 missfire.Am suspecting intake gaskets but not sure.
Sometimes, you can use a digital multimeter to find spark misfire. Engine idling in park, touch the spark plug wires, one at a time. You DON'T take the spark plug wire loose or penetrate the insulation, it's an inductive reading. If the misfire is present at idle? Some of the readings I've seen in the past is like .6 or .7 volt, not even a full volt. But if that reading is bouncing off zero, you found it. I haven't really check into your ignition coil or module?
Did you use a gage and check proper fuel pressure, my info says 56--62 psi, key on engine off. As far as compression tests, compare readings from one cylinder to the others. All readings should be within 70--75% of each other, from the highest to the lowest. Just my opinion.
Sounds like the only thing left is the valve lash. If the intake gasket was bad, it would most likely cause a vacuum leak and effect the overall performance of the engine. You may also notice some oil consumption as well. Also, verify the firing order is correct.
SOURCE: cylinder 5 missfire 1999 tahoe
How is the pressure in the fuel rail? a low pressure will cause erratic firing of the injectors - the further down the rail u get usually the worse the problem. If the fuel filter was not changed regularly or if the vehicle stood for a while, dirty fuel/standing fuel at some time in the recent past, this **** will accumulate in tyhe injectors. To avoid spending a loada cash, swap a few injectors around and see if the problem moves with the injector.
SOURCE: 2000 Chevy Venture with a code reading " #1 cylinder missfire"
Remove the large hose that is coming from the air filter at the throttle body. There is a large butterfly inside that is open when you push on the gas pedal. Get some carb cleaner and clean this as good as you can. See if this helps or cures your problem
SOURCE: 2005 5.3 1500 pickup multi cylinder misfar
Just so I learn something
Spark plugs -wear ,seldom misfire
Injectors and Coils-need to be component
tested,before I would replace
Testing-- is using a meter,oscilloscope,etc.
Same on O2 Sensor,scope is only way to
see switching time.
I would suggest something common to
multi cyl misfires.
Because you get a code for #1,doesn't mean
that coil is bad. You may have to walk a new
coil from one cyl to the next.
CPS Sensor ?
Is there a cam sensor on that engine?
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