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So I just read that in order for a misfire DTC to be set the Mode 6 misfire count has to exceed the threshold which IIRC was 65,535 misfires.
 

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Discussion Starter #102
Got my tune revision installed no more miss fire on #6 but the boost is down to 15psi now which is a loss of 6psi over last tune file
 

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Discussion Starter #104
I do not try user blackhawk77
 

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Do any of you have a stock HPTuners read for a MKZ 3.0 by any chance?
If you get one, let me know what the engine size is in the general table.
 

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So I just read that in order for a misfire DTC to be set the Mode 6 misfire count has to exceed the threshold which IIRC was 65,535 misfires.
This is not true. The misfire monitor watches the number of misfires that occur during a 200 and 1000 RPM period, then based on the rate of misfire, will set a DTC. The 200 RPM period is basically used to determine if the catalyst will be damaged by the number of misfires in that period and whether a DTC needs to be set or the cylinder disabled. It also uses the 200 RPM monitor under high load conditions. The 1000 RPM period is more for emissions related/slight misfires that will not cause catalyst damage. At 2000 RPM with a dead miss, you'd have to drive for 30 minutes to set a misfire code with a threshold 65,535 misfires! Lol
 

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Discussion Starter #107
I do not think my methanol is working correctly as my data log has a 4.1 knock reading on my test run this morning
 

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This is not true. The misfire monitor watches the number of misfires that occur during a 200 and 1000 RPM period, then based on the rate of misfire, will set a DTC. The 200 RPM period is basically used to determine if the catalyst will be damaged by the number of misfires in that period and whether a DTC needs to be set or the cylinder disabled. It also uses the 200 RPM monitor under high load conditions. The 1000 RPM period is more for emissions related/slight misfires that will not cause catalyst damage. At 2000 RPM with a dead miss, you'd have to drive for 30 minutes to set a misfire code with a threshold 65,535 misfires! Lol
I have read several times that it takes a long time of misfiring for the actual DTC to be set. As you recall before I'd get severe misfiring and shuddering (same symptoms as the F-150s) along with stallouts but never once did a DTC get set. I've had the DTC set before for random misfires P0300 and random P030x on my 2000 Crown Vic with aftermarket cams but those symptoms weren't nearly as bad as that on the Fusion Sport, and it took a long time (as in number of drive cycles) before those DTCs would set. I've heard the misfiring detection system referred to as a neural network as far back as in the late 90s/early 00's by Ford powertrain engineers.
 

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I have read several times that it takes a long time of misfiring for the actual DTC to be set. As you recall before I'd get severe misfiring and shuddering (same symptoms as the F-150s) along with stallouts but never once did a DTC get set. I've had the DTC set before for random misfires P0300 and random P030x on my 2000 Crown Vic with aftermarket cams but those symptoms weren't nearly as bad as that on the Fusion Sport, and it took a long time (as in number of drive cycles) before those DTCs would set. I've heard the misfiring detection system referred to as a neural network as far back as in the late 90s/early 00's by Ford powertrain engineers.
Yeah, a DTC will not usually set unless the misfire is severe and persists. If you have a couple hiccups for couple seconds like we’re experiencing, a DTC will be pending but won’t set as a hard fault unless the misfire continues to occur. Since the misfire goes away fast, no DTC is set. The information I posted is from the 2019 Ford OBD Theory and Operations manual, it’s a giant manual that explains how all the emissions systems function.
 

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Discussion Starter #110
How much does a miss fire effect KR ?
 

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Not as much as a bad timing chain, guides, and tensioners. :)
 

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Discussion Starter #112
I should not have that problem at 24k miles
 

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I should not have that problem at 24k miles
No,but its a crab shoot. I,ve done 3.5's with less than 100,000, and one with 280,000. I would hope Ford figured out the weak link and didn't design a repeat of the 3.5 when they came up with the 2.7
 

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Discussion Starter #114
I am gonna compression test the #6 cylinder tomorrow just in case , can one of the member please post compression test specs for the 2.7
 

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I am gonna compression test the #6 cylinder tomorrow just in case , can one of the member please post compression test specs for the 2.7
I looked through the FSM and could only find a generic chart. "The indicated compression pressures are considered within specification if the lowest reading cylinder is at least 75% of the highest reading. Refer to the Compression Pressure Limit Chart."
 

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Discussion Starter #116
thanks Metro
 

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No problem, hopefully that made sense. It wasn't as easy to find as I'd hoped and it didn't make sense to me. But I am curious what you find out since cylinder #6 seems to be prone to misfires on my engine as well.
 
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