datalogging random misfire
10-30-2014, 09:34 PM
#1
datalogging random misfire
I am using the Diablo itune datalog option to find a random misfire on a 2008 LS3 with 40K miles, original plugs. I am able to record some misfire counts and I have been able to use the diablo as a passthrough device to watch for misfires on the laptop with cylinder midfire history counts. No check engine light or codes have been logged due to a misfire because the count is too low. I have changed wires, it made no difference. I get most frequent misfire counts on cyl 2 and 8. Both have logged up to a 4 count and other cylinders have shown only a 1 or 2 misfire count. I did swap coils on cylinder 2 and 8 with 4 and 6 coils. The misfire counts did not move with the coil swap. Perhaps I am looking for nothing that needs to be corrected, but I can feel the misfires at random. Perfect idle for 5 to 10 seconds and then 2 to 4 recorded misfires and it can be felt in the idle. I did record a short acceleration and hiway drive and the engine feels as if it has no hard misfires.
Am I trying to solve a non-issue? What is normal on a cylinder history misfire count?
Am I trying to solve a non-issue? What is normal on a cylinder history misfire count?
11-10-2014, 10:45 PM
#4
I wasn't sure what the last post was about until I saw the members name.
In case anyone searches for this same issue, I will respond with an update. Replaced the coil that recorded the most misfires. Engine runs smoother at idle and misfire on cyl 8 is gone.
In case anyone searches for this same issue, I will respond with an update. Replaced the coil that recorded the most misfires. Engine runs smoother at idle and misfire on cyl 8 is gone.
11-13-2014, 01:50 PM
#5
what about the other misfires? I have seen some random misfires on mine, and have a neighbor with an ls1 thats been chasing the same damn thing... same deal with swapping the coils not changing anything
maybe the coils just need to all be replaced at once when this situation arises?
maybe the coils just need to all be replaced at once when this situation arises?
11-13-2014, 09:18 PM
#6
I bought a Borg Warner coil from advanced auto. It was in an ac delco bag inside the BW box. About $54 after discounts. I do not want to replace the other 7 coils.
I had the car at the dealer a few months back for another warranty issue and I asked them to check into a possible misfire with no CEL. They found nothing with the GM tool so using the Diablo intune is not going to be any better. It won't do half of what the GM test equipment tools will do. I did change the plug wires, I knew better but did it anyway. Blindly swapping parts is not the way to find an issue. Right now it runs fine so I'm not going to keep looking for such a minor issue.
I had the car at the dealer a few months back for another warranty issue and I asked them to check into a possible misfire with no CEL. They found nothing with the GM tool so using the Diablo intune is not going to be any better. It won't do half of what the GM test equipment tools will do. I did change the plug wires, I knew better but did it anyway. Blindly swapping parts is not the way to find an issue. Right now it runs fine so I'm not going to keep looking for such a minor issue.
11-22-2014, 12:03 AM
#7
Le Mans Master
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St. Jude Donor '13-'14-'15
The main issues about misfires is to find out for sure if in fact they are
"real OR false" If real then you can sort out a plug--wire--coil--injector- wiring---If you deem that it is False---a false misfire is very common with any LS engine that has been modded----These false mis-fires can be eliminated with tuning---but NOT a handheld---either HP or EFILIVE--
"real OR false" If real then you can sort out a plug--wire--coil--injector- wiring---If you deem that it is False---a false misfire is very common with any LS engine that has been modded----These false mis-fires can be eliminated with tuning---but NOT a handheld---either HP or EFILIVE--