Possible misfires at idle

[Mosey]

Hello, I have noticed possible misfires at idle whenever I tow. Of course I notice this only while in tow-haul mode as the engine does not turn off when at stop lights. Once off idle the engine is smooth. One last observation - whenever I am in tow-haul mode the engine sound is more pronounced, even a bit raspy under load.

My PB just rolled over 50k miles and I am wondering if now is the time to swap out plugs, but before doing that I would like to determine if the ECM is recording misfires. I own an Innova scanner (midlevel model) and I also have Forscan. Will either of these tools let me monitor for misfires in real-time? No DTCs are set.

suggestions? Thanks.

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[RcFlyer330]

Yes, forscan will let you monitor misfires counts live under the dashboard function. The pid was named NM for number of misfires but that was back in 2010 its probally still similar though. This pid would show the total number of misfire counts from all cylinders. If there is a miss then run the mode 6 data test in the tests function of forscan. The mode 6 test will tell you what cylinder is misfiring and its misfire count. I think the mode 6 may also show history misfire count too but dont quote me on that.

 

[Jerome10]

I kinda have this sometimes if engine is actually on at a light.

I’ve read around a bit and it doesn’t seem uncommon with the 3.5L.

I’d be curious about misfires but I kinda think this is one of those slightly annoying “normal” things.

 

[FaaWrenchBndr]

50k is certainly a good time to change plugs.

 

[Jasco]

Hello, I have noticed possible misfires at idle whenever I tow. Of course I notice this only while in tow-haul mode as the engine does not turn off when at stop lights. Once off idle the engine is smooth. One last observation - whenever I am in tow-haul mode the engine sound is more pronounced, even a bit raspy under load.

My PB just rolled over 50k miles and I am wondering if now is the time to swap out plugs, but before doing that I would like to determine if the ECM is recording misfires. I own an Innova scanner (midlevel model) and I also have Forscan. Will either of these tools let me monitor for misfires in real-time? No DTCs are set.

suggestions? Thanks.

Mine does this exact same thing in Tow/Haul mode only, while stopped. In Normal mode stopped idling it is smoother. I’m at 26k miles. Did you figure this out or take it in?

 

[Mosey]

Mine does this exact same thing in Tow/Haul mode only, while stopped. In Normal mode stopped idling it is smoother. I’m at 26k miles. Did you figure this out or take it in?

No, not really a big concern. I plan on changing out the plugs.

 

[Porpoise Hork]

Mine does this too when in tow mode. Has since day 1 actually. Never had any codes and no miss-fire events seen when monitoring the engine with both Forscan and my OBD scan tool.

I just chalked it up to the system likely keeping both the ICE and EV motor engaged at idle to provide as much torque off the line as possible when towing.

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