I had a pretty bad misfire on my 2010 GMC Sierra 5.3. I hooked up my Bi-Directional scan tool and identified that cyl 3 was the culprit. I swapped plugs and coils and the misfire stayed on #3. I swapped wires and the misfire moved with the wire. I went out and bought a new set of Delco Wires. Truck is running very smooth and has noticeable increase in power. I decided to hook up the scan tool and just see how everything is doing. Showed #3 has 2 misfires at idle every few cycles or so. No problem under acceleration. I decided to tweak my HP Tune because I had used it to turn off DOD and to disable flex fuel. Disabling flex fuel would obviously make the truck have to compensate for the 10% ethanol, but I figured it would be well within the PCM's ability to a just the fuel ratio. I decided to tweak it to allow a parameter of 8%-11% ethanol because our fuel is supposed to have no more than 10%. I did this and took it for a drive. Everything sounds and feels good. I hooked up my Bi-Directional scan tool and it bounced around saying I had a couple of misfires per every couple of cycles on 2 and then 5 and then 3 and then 8. It would take a few cycles at idle to show anything. Each cycle was 99 revolutions. it would register a high of 4-6 misfires per cycle and a low of 2 misfires per every couple of cycles. I hooked up my HP Tuners to do a log because I wanted to have a longer history than 99 Revolutions. HP Tuners connected showed absolutely no misfires at all. The O2 sensors on the Bi-Directional scan tool stayed pretty consistent, but the O2 sensors on the HP Tuners showed the values jumping around substantially more. I took the truck for a good long drive with the HP Tuners logging to see if I could find a misfire but after a 20min drive around town and setting the cruise on back roads at different speeds and of course sitting idle still returned no misfires. I did notice the fuel trims also where more consistent although Bank one is always calling for more fuel. Bank 2 normally calls for .8% and bank 1 calls for 5-6%. Is it possible that the Bi-Directional scan tool is wrong. Maybe after changing the flex fuel settings, the trucks ECU needs to sort out what it needs? Any Ideas?
How about, I only have Miss fires at idle and when the A/C is on, the Miss fires increase but runs fine under normal driving conditions. Even full throttle is clean. Im running heads and 228/232 TSP cam and Hinson headers and k&n cold air.
Would have also been useful to use the IR gun to confirm your findings. I've used these PIDs to try to diagnose a slight miss and the scanner didn't really help me. I ultimately ran the engine in pitch black and found sparks around 2 plugs.
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I had a pretty bad misfire on my 2010 GMC Sierra 5.3. I hooked up my Bi-Directional scan tool and identified that cyl 3 was the culprit. I swapped plugs and coils and the misfire stayed on #3. I swapped wires and the misfire moved with the wire. I went out and bought a new set of Delco Wires. Truck is running very smooth and has noticeable increase in power. I decided to hook up the scan tool and just see how everything is doing. Showed #3 has 2 misfires at idle every few cycles or so. No problem under acceleration. I decided to tweak my HP Tune because I had used it to turn off DOD and to disable flex fuel. Disabling flex fuel would obviously make the truck have to compensate for the 10% ethanol, but I figured it would be well within the PCM's ability to a just the fuel ratio. I decided to tweak it to allow a parameter of 8%-11% ethanol because our fuel is supposed to have no more than 10%. I did this and took it for a drive. Everything sounds and feels good. I hooked up my Bi-Directional scan tool and it bounced around saying I had a couple of misfires per every couple of cycles on 2 and then 5 and then 3 and then 8. It would take a few cycles at idle to show anything. Each cycle was 99 revolutions. it would register a high of 4-6 misfires per cycle and a low of 2 misfires per every couple of cycles. I hooked up my HP Tuners to do a log because I wanted to have a longer history than 99 Revolutions. HP Tuners connected showed absolutely no misfires at all. The O2 sensors on the Bi-Directional scan tool stayed pretty consistent, but the O2 sensors on the HP Tuners showed the values jumping around substantially more. I took the truck for a good long drive with the HP Tuners logging to see if I could find a misfire but after a 20min drive around town and setting the cruise on back roads at different speeds and of course sitting idle still returned no misfires. I did notice the fuel trims also where more consistent although Bank one is always calling for more fuel. Bank 2 normally calls for .8% and bank 1 calls for 5-6%. Is it possible that the Bi-Directional scan tool is wrong. Maybe after changing the flex fuel settings, the trucks ECU needs to sort out what it needs? Any Ideas?
Many thanks and regards of México
Great Info , Thank for the vid .
Thanks so much for watching!
Thanks will do this to find my issue
Awesome! Let us know if it's working for you.
Good video. BTW, the part I didn't like: at minute 5:00 you stated ...We start replacing things like coils, plugs, plug wires......
That's right. Thanks for your feedback!
Thanks for the info
Beuller?
How about, I only have Miss fires at idle and when the A/C is on, the Miss fires increase but runs fine under normal driving conditions. Even full throttle is clean. Im running heads and 228/232 TSP cam and Hinson headers and k&n cold air.
mptorecon what was the fix?
I know this is old, but i get the same thing.
My HPTuners doesn't have misfire under Engine
Whats an acceptable amount of misfires on a fbo 6th gen camaro cylinder 3 has 2 counts and cylinder 8 has 1
Why can't I do this for a 2006 f150? When I go to the channels list I don't have the option for individual cylinders only a total misfired channel.
The channels are not universal across all manufacture platforms and ECUs. We suggest contacting support@hptuners.com to see if they can assist.
Any reason why my misfire history wouldn’t be staying nor adding up the amount of total misfires ?
Anything on Gen3 Hemi's?
For some reason my 2006 TBSS with a large cam shows 0 misfires? Is it turned off in the tune?
407ForRent more than likely it is, most tuners will turn misfire counter off due to a big cam.
How much variation between cylinders is conclusive evidence of a misfire? What does a stock engine look like if you ran the same scan?
Would have also been useful to use the IR gun to confirm your findings. I've used these PIDs to try to diagnose a slight miss and the scanner didn't really help me. I ultimately ran the engine in pitch black and found sparks around 2 plugs.
@@MugelloZ06 That was a smart idea looking in the dark for spark jump.