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Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!

Problem child

  • welj31
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4 years 7 months ago #47703 by welj31
Problem child was created by welj31
2004 Tahoe z71 z flex fuel. Cant seem to be able to copy and paste all info here but have added screen shots.
P0300 is only code.
Tested all the usual stuff again would post results but copy and paste not working.

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4 years 7 months ago #47704 by welj31
Replied by welj31 on topic Problem child
Screen shots after warmed up
Attachments:

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4 years 7 months ago #47706 by Paul P.
Replied by Paul P. on topic Problem child
Reset your fuel alcohol with your scan tool, and perform a Crank Variation relearn with your scan tool.

Do you feel misfires, cause your counters don't show any. Do you own a scope?
Never stop Learning.

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4 years 7 months ago #47707 by Tyler
Replied by Tyler on topic Problem child
Thanks for the screenshots! Much appreciated.

Do any of the Misfire History Cylinder __ PIDs show counts? They should since the P0300 is stored.

Speaking of, when does the Freeze Frame data say the code set? Idle, WOT, cruise? Cold, hot?

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4 years 7 months ago #47708 by welj31
Replied by welj31 on topic Problem child
yes you can feel the mis fires less so after warm but still present. no scope

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4 years 7 months ago #47709 by welj31
Replied by welj31 on topic Problem child

Tyler wrote: Thanks for the screenshots! Much appreciated.

Do any of the Misfire History Cylinder __ PIDs show counts? They should since the P0300 is stored.

Speaking of, when does the Freeze Frame data say the code set? Idle, WOT, cruise? Cold, hot?

i am not sure how to get to FF data but here is count

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4 years 7 months ago #47713 by welj31
Replied by welj31 on topic Problem child
RELEARN HELPED SMOOTH OUT A LITTLE BUT STILL MISFIRING

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4 years 7 months ago #47714 by Tyler
Replied by Tyler on topic Problem child
Were there any history miss counts on cylinder #7 or #8? If not, it sure looks like #5 is the main offender. Does the #5 Current counter tick up at idle, or while driving?

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4 years 7 months ago #47716 by welj31
Replied by welj31 on topic Problem child
Just swapped coils around again and misfire remains in 8/6.

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4 years 7 months ago #47717 by welj31
Replied by welj31 on topic Problem child

welj31 wrote: Just swapped coils around again and misfire remains in 8/6.

this is #8 plug

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4 years 7 months ago - 4 years 7 months ago #47718 by Tyler
Replied by Tyler on topic Problem child

welj31 wrote: Just swapped coils around again and misfire remains in 8/6.


Sorry, I was misreading Giotto. :blush: So the miss counts are on #6 and #8.

Watch the Current miss counts to see under what conditions they tick up.

EDIT: Never mind. That plug sure looks like a dead misfire.

Are you able to do a relative compression test? Or, do you know what to listen for when doing a clear flood crank?
Last edit: 4 years 7 months ago by Tyler.

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4 years 7 months ago #47719 by welj31
Replied by welj31 on topic Problem child
#5 ?

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4 years 7 months ago #47720 by welj31
Replied by welj31 on topic Problem child

Tyler wrote:

welj31 wrote: Just swapped coils around again and misfire remains in 8/6.


Sorry, I was misreading Giotto. :blush: So the miss counts are on #6 and #8.

Watch the Current miss counts to see under what conditions they tick up.

EDIT: Never mind. That plug sure looks like a dead misfire.

Are you able to do a relative compression test? Or, do you know what to listen for when doing a clear flood crank?

will do thanks for the help

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4 years 7 months ago #47722 by welj31
Replied by welj31 on topic Problem child

Tyler wrote:

welj31 wrote: Just swapped coils around again and misfire remains in 8/6.


Sorry, I was misreading Giotto. :blush: So the miss counts are on #6 and #8.

Watch the Current miss counts to see under what conditions they tick up.

EDIT: Never mind. That plug sure looks like a dead misfire.

Are you able to do a relative compression test? Or, do you know what to listen for when doing a clear flood crank?

will do thanks for the help
pic one is at 600 rpm
pic two is at 1000 rpm
pic three is at 1500 rpm

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4 years 7 months ago #47723 by welj31
Replied by welj31 on topic Problem child
no i dont know what to listen for ?
basic compression test showed
1=165
2=175
3=170
4=180
5=170
6=180
7=170
8=175
just swapped plug around its good

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4 years 7 months ago #47725 by VegasJAK
Replied by VegasJAK on topic Problem child
That #8 plug looks pretty wet. Is it oil or fuel?
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does

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4 years 7 months ago #47726 by welj31
Replied by welj31 on topic Problem child
it is wet but i cant tell what it it. smells odd not like fuel or coolant

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4 years 7 months ago #47727 by VegasJAK
Replied by VegasJAK on topic Problem child
Clear flood test... Hold accelerator to floor while cranking engine. Listen to rythem of starter motor. Should be consistent rem rem rem starter sound. Any hick ups tells you one or more cylinders has a problem.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does

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4 years 7 months ago - 4 years 7 months ago #47729 by welj31
Replied by welj31 on topic Problem child
i swapped plug 8 with plug 2. no scanner says misfire is in cylinder 1/6 WTH? will try the flood crank now.......cranks normal no odd ups or downs
BTW it starts on the 3 rotation
Last edit: 4 years 7 months ago by welj31.

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4 years 7 months ago #47730 by VegasJAK
Replied by VegasJAK on topic Problem child
Hmmm. Has to be oil then. Compression on #8 looks Ok, but if oil is in the cylinder you will get a high compression rate as a posed to a dry cylinder. Does the pressure bleed off?

Put your thumb over plug hole and crank. Can you tell now if oil or ?
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does

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