Is This a Normal Misfire History Pattern?

[TommyGloves]

So on my SSEi with the VS cam, I've always set the P0300 code regularly after a week or so of setting the code (past 3 years, plugs did not matter). Anyway, I've never logged the misfire history until this past month.

I'm curious, is this a normal misfire history? (I never see, or at aleast recorded, any misfires under throttle. These all seem to have happened where Throttle % = 0)

This is the cumulative totals for the past 30 days or so. I've had two instances where #4 misfires immediately at start-up. Immediate counts got up to ~200 until I put it into gear.

1 5292 2 584
3 10748 4 25941
5 5543 6 122

I'm going to be swapping out plugs this weekend (its time).

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[Alacran]

i thought with certain cams you had to disable the missfire codes. Is it actually missing?

 

[Turbocharged400sbc]

So on my SSEi with the VS cam, I've always set the P0300 code regularly after a week or so of setting the code (past 3 years, plugs did not matter). Anyway, I've never logged the misfire history until this past month.

I'm curious, is this a normal misfire history? (I never see, or at aleast recorded, any misfires under throttle. These all seem to have happened where Throttle % = 0)

This is the cumulative totals for the past 30 days or so. I've had two instances where #4 misfires immediately at start-up. Immediate counts got up to ~200 until I put it into gear.

1 5292 2 584
3 10748 4 25941
5 5543 6 122

I'm going to be swapping out plugs this weekend (its time).

yes thats normal missfire counts are usually counting up on the adjacent firing order cylinders, the highest count is the cylinder that is missfiring.
the pcm looks at the 18x reference pulses for the misfire data and it has nowhere near the resolution of the newer 36x (or 36-1) reluctors so the counts will rise for the cylinders firing closest to the major counts.

when you pull out the #4 plug check for carbon or soot that will lead to a carbon tracking (side jumping) spark, if it's worse than the rest you may want to do a hot and cold engine leakdown test to check ringseal.

dont forget to play frankenstein and run yer hand along the wire while it's running cold and see if you feel any voltage leakage
it's better than coffee

 

[TonzKnock-G]

I forgot what i had on the GTP but I know that 3 & 4 was the highest.

 

[Angus]

dont forget to play frankenstein and run yer hand along the wire while it's running cold and see if you feel any voltage leakage
it's better than coffee

did that with my bimmer to find why it was misfiring. Yep the wires were shot and my arm didn't feel right the rest of the day...

 

[Ron Vogel]

yes thats normal missfire counts are usually counting up on the adjacent firing order cylinders, the highest count is the cylinder that is missfiring.
the pcm looks at the 18x reference pulses for the misfire data and it has nowhere near the resolution of the newer 36x (or 36-1) reluctors so the counts will rise for the cylinders firing closest to the major counts.

when you pull out the #4 plug check for carbon or soot that will lead to a carbon tracking (side jumping) spark, if it's worse than the rest you may want to do a hot and cold engine leakdown test to check ringseal.

dont forget to play frankenstein and run yer hand along the wire while it's running cold and see if you feel any voltage leakage
it's better than coffee

I prefer to mist water on them in a dark garage...less painful and it's a cool light show. I never did get why #4 always misfires more than others. It happens on almost every L67 I've scanned.

 

[Turbocharged400sbc]

I prefer to mist water on them in a dark garage...less painful and it's a cool light show. I never did get why #4 always misfires more than others. It happens on almost every L67 I've scanned.

guess which cylinder gets more oil thrown onto the cylinder walls than any other....GM needed to go with an oil ring bigger than 3mm or at least do like i did and drill more holes through the skirt for better scraping

 

[02BlueGT]

guess which cylinder gets more oil thrown onto the cylinder walls than any other....GM needed to go with an oil ring bigger than 3mm or at least do like i did and drill more holes through the skirt for better scraping

I remembered when you explained this..... Now we know how to test if you install a small baffle there if it helps any

 

[Turbocharged400sbc]

I remembered when you explained this..... Now we know how to test if you install a small baffle there if it helps any

i know it'll help...#4 pistons always come out with clean oil in the #1 and #2 compression ring grooves...oils def getting past the oil ring...

 

[02BlueGT]

i know it'll help...#4 pistons always come out with clean oil in the #1 and #2 compression ring grooves...oils def getting past the oil ring...

I know, but if it shows a significant drop, you can tell say look at this, and not have to tear open the block to find oil on the compression rings...... I don't mean to prove to you, but to prove to any naysayers

 

[Turbocharged400sbc]

I know, but if it shows a significant drop, you can tell say look at this, and not have to tear open the block to find oil on the compression rings...... I don't mean to prove to you, but to prove to any naysayers

who cares about naysayers? most live in their own "you cant make any improvements... the oems do it perfect" world lol

 

[02BlueGT]

who cares about naysayers? most live in their own "you cant make any improvements... the oems do it perfect" world lol

Wait oem isn't perfect