cylinder 5 missfire
#1
cylinder 5 missfire
So i have a 2000 chevy 5.3l, swapped into my 79 chevy 4x4.
runs about 50-60 psi depending on the vacuum of the engine.
I just recently started having a missfire, not bad enough to throw the check engine light on, (sometimes it will flash like a missfire should)
today i hooked up efi live, and see that cylinder 5 has 100 missfire counts, so i check volts at the coil pack and at the injector.. both 14.2v
try swapping plug wires, and plugs around and it stays there.
I even swapped coil packs but cylinder 5 still holds that missfire.....
I CAN ONLY THINK A BAD CAM OR CRANK SENSOR..
anyone have any better ideas than i have?
runs about 50-60 psi depending on the vacuum of the engine.
I just recently started having a missfire, not bad enough to throw the check engine light on, (sometimes it will flash like a missfire should)
today i hooked up efi live, and see that cylinder 5 has 100 missfire counts, so i check volts at the coil pack and at the injector.. both 14.2v
try swapping plug wires, and plugs around and it stays there.
I even swapped coil packs but cylinder 5 still holds that missfire.....
I CAN ONLY THINK A BAD CAM OR CRANK SENSOR..
anyone have any better ideas than i have?
#3
i can only think its a ECM problem. because if i had compression missfire i think it would be alot worse than it is.
#4
i swapped a coil from a good cylinder, and it didnt follow. i see 14 volts to the injector and the coil. i wonder if the ground is gone on one of them? where does the ground go?
i can only think its a ECM problem. because if i had compression missfire i think it would be alot worse than it is.
i can only think its a ECM problem. because if i had compression missfire i think it would be alot worse than it is.
#7
i did a compression check and it shot to 150psi almost as soon as it turned over
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#10
#13
pretty much what you do is bring the cylinder up to TDC and the "gauge" has a hose with a set of threads that screw in like a spark plug... you hook the gauge up and zero it out with out having the hose into the cylinder attached... then you hook it up and it will show you the % of leakdown...
#14
pretty much what you do is bring the cylinder up to TDC and the "gauge" has a hose with a set of threads that screw in like a spark plug... you hook the gauge up and zero it out with out having the hose into the cylinder attached... then you hook it up and it will show you the % of leakdown...
i would think if it built 150psi i wouldnt have much leakdown.. but am i wrong?
#15
my motor for instance 2000 ls1 had 165 iirc compression on cylinder 6... it would miss at idle and low rpms...under 1200... once it got above that magic number the miss would stop and she ran good...
turns out i either had a bad seat or bent valve... when i filled the port( cant remember if it was intake or exhaust) with the heads off the motor water leaked thru into what would be the combustion chamber. none of the other valves did that...
so to answer your question... you may have leakdown... I didnt own a leakdown gauge at the time of me diagnoseing my car...
now onto another thought... is this only at idle? or will it occur only under load or is it random?
turns out i either had a bad seat or bent valve... when i filled the port( cant remember if it was intake or exhaust) with the heads off the motor water leaked thru into what would be the combustion chamber. none of the other valves did that...
so to answer your question... you may have leakdown... I didnt own a leakdown gauge at the time of me diagnoseing my car...
now onto another thought... is this only at idle? or will it occur only under load or is it random?
#16
my motor for instance 2000 ls1 had 165 iirc compression on cylinder 6... it would miss at idle and low rpms...under 1200... once it got above that magic number the miss would stop and she ran good...
turns out i either had a bad seat or bent valve... when i filled the port( cant remember if it was intake or exhaust) with the heads off the motor water leaked thru into what would be the combustion chamber. none of the other valves did that...
so to answer your question... you may have leakdown... I didnt own a leakdown gauge at the time of me diagnoseing my car...
now onto another thought... is this only at idle? or will it occur only under load or is it random?
turns out i either had a bad seat or bent valve... when i filled the port( cant remember if it was intake or exhaust) with the heads off the motor water leaked thru into what would be the combustion chamber. none of the other valves did that...
so to answer your question... you may have leakdown... I didnt own a leakdown gauge at the time of me diagnoseing my car...
now onto another thought... is this only at idle? or will it occur only under load or is it random?
i can try leakdown if i can come up with a gauge.. but this was just a all the sudden deal. didnt start over time or anything. one day came to start it and had that issue.
#17
my motor for instance 2000 ls1 had 165 iirc compression on cylinder 6... it would miss at idle and low rpms...under 1200... once it got above that magic number the miss would stop and she ran good...
turns out i either had a bad seat or bent valve... when i filled the port( cant remember if it was intake or exhaust) with the heads off the motor water leaked thru into what would be the combustion chamber. none of the other valves did that...
so to answer your question... you may have leakdown... I didnt own a leakdown gauge at the time of me diagnoseing my car...
now onto another thought... is this only at idle? or will it occur only under load or is it random?
turns out i either had a bad seat or bent valve... when i filled the port( cant remember if it was intake or exhaust) with the heads off the motor water leaked thru into what would be the combustion chamber. none of the other valves did that...
so to answer your question... you may have leakdown... I didnt own a leakdown gauge at the time of me diagnoseing my car...
now onto another thought... is this only at idle? or will it occur only under load or is it random?
also, sometimes my ecm wont even pick up a missfire... even if the wire is disconnected on the coil and injector.. but sometimes it will and will flash as well. which is weird.
even unplug a good running cylinder and it wont pick it up sometimes. swapped crank sensor and still the same
#18
my motor for instance 2000 ls1 had 165 iirc compression on cylinder 6... it would miss at idle and low rpms...under 1200... once it got above that magic number the miss would stop and she ran good...
turns out i either had a bad seat or bent valve... when i filled the port( cant remember if it was intake or exhaust) with the heads off the motor water leaked thru into what would be the combustion chamber. none of the other valves did that...
so to answer your question... you may have leakdown... I didnt own a leakdown gauge at the time of me diagnoseing my car...
now onto another thought... is this only at idle? or will it occur only under load or is it random?
turns out i either had a bad seat or bent valve... when i filled the port( cant remember if it was intake or exhaust) with the heads off the motor water leaked thru into what would be the combustion chamber. none of the other valves did that...
so to answer your question... you may have leakdown... I didnt own a leakdown gauge at the time of me diagnoseing my car...
now onto another thought... is this only at idle? or will it occur only under load or is it random?
hopefully this helps some.
idk what else to do besides maybe a bad ecm