Mode 6 Question
Thread Starter
5 Year Member
Joined: Mar 2013
Posts: 117
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From: El Paso, TX
Mode 6 Question
OK I am a little stumped on this one. I have a 2003 F150 SCrew 4wd with the 5.4l motor. I use Forscan to monitor my truck as I drive. The other day it developed a misfire, and according to the mode 6 test there was a 12.26% misfire detected on cylinder 5. I investigated it today and it had a partially broken wire on the COP connector. I replaced the connector as well as the COP and the plug while I was there.
Then I went for a test drive and no misfire was detected and no misfire percentage on cylinder 5. But there is now a 12.26% misfire detected on cylinder 7!
Often times when I start my truck in the morning a single misfire will be detected. I then drive to work and it doesn't detect anymore than that. Between this and the exact same misfire percentage .owing from cylinder to cylinder leads me to believe that maybe the data isn't accurate from Forscan.
Anyone ever experienced something like this? The perfectionist in me wants there to be no misfire or percentage detected at all, but not sure I will ever see that.
Then I went for a test drive and no misfire was detected and no misfire percentage on cylinder 5. But there is now a 12.26% misfire detected on cylinder 7!
Often times when I start my truck in the morning a single misfire will be detected. I then drive to work and it doesn't detect anymore than that. Between this and the exact same misfire percentage .owing from cylinder to cylinder leads me to believe that maybe the data isn't accurate from Forscan.
Anyone ever experienced something like this? The perfectionist in me wants there to be no misfire or percentage detected at all, but not sure I will ever see that.
5 Year Member
Joined: May 2015
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Well you're correct because there's always misfires. That's a consequence of trying to control the O2 ratio where it needs to be. But it is typically very low and unnoticeable . That's why there has to be a threshold at where the computer flags it as a problem, basically at several percent. It counts the misfires routinely when the monitor runs and only flags it when it's high enough to be considered a problem .
But you should go ahead and solve the problem on number 7.
But you should go ahead and solve the problem on number 7.
Senior Member
Joined: Mar 2021
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If the Ignition has not had any service for a long time, the coils, boots, moisture in the wells needs attention and clean up. The coil boots don't seal all that well.
My 02 ran over 321k miles without any continuous misfires set in mode 6, test 53.
When they did occur, it was the Coil or boot and was cleared with service done.
My 2018 5L runs with no misfire registrations, so far.
Only other time is with bad gas in any engine.
Having a Scanner to take a look now and then detects a misfire problem before they get to the point of a hard misfire and a code set.
My 02 ran over 321k miles without any continuous misfires set in mode 6, test 53.
When they did occur, it was the Coil or boot and was cleared with service done.
My 2018 5L runs with no misfire registrations, so far.
Only other time is with bad gas in any engine.
Having a Scanner to take a look now and then detects a misfire problem before they get to the point of a hard misfire and a code set.