Pattern to random cylinder misfires
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4th Gear
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Pattern to random cylinder misfires
Hoping someone may have experienced a similar strange behavior checking cylinder misfires and could provide some explanation…
Following a break-down on my motorhome I started monitoring cylinder misfires and I’ve noticed a pattern to the random misfires. On three test drives about 60 miles. Using Torque Pro for mode06 info I finished up with a test results scan to retrieve the misfire information. On all three tests I had 5 cylinders with misfire counts. Each test drive had a different 5 cylinder combination. In all three test drives the number of misfires was either 64 or 65, or a multiple of 65.. i.e.; 3 cylinders @ 65, 1 @ 130 and 1 @ 260. Or another test returned 2 cylinders @ 64 and 3 @ 129, but so far always a total of 5 different cylinders reporting.
I’m beginning to wonder if there is an interference issue causing this. At no time do I “feel” the misfire.. all smooth running.
2003 Ford F53 motorhome chassis, 6.8 V10 35,000 miles
BAFX bluetooth OBD2 scanner ~ Torque Pro on Android tablet
Following a break-down on my motorhome I started monitoring cylinder misfires and I’ve noticed a pattern to the random misfires. On three test drives about 60 miles. Using Torque Pro for mode06 info I finished up with a test results scan to retrieve the misfire information. On all three tests I had 5 cylinders with misfire counts. Each test drive had a different 5 cylinder combination. In all three test drives the number of misfires was either 64 or 65, or a multiple of 65.. i.e.; 3 cylinders @ 65, 1 @ 130 and 1 @ 260. Or another test returned 2 cylinders @ 64 and 3 @ 129, but so far always a total of 5 different cylinders reporting.
I’m beginning to wonder if there is an interference issue causing this. At no time do I “feel” the misfire.. all smooth running.
2003 Ford F53 motorhome chassis, 6.8 V10 35,000 miles
BAFX bluetooth OBD2 scanner ~ Torque Pro on Android tablet
Fleet Owner
Joined: Aug 2010
Posts: 21,253
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From: Reynoldsburg, Ohio
I am totally guessing here but could this Bluetooth OBD-ll be the cause of what we might call signal interference? If not could the PCM be having issues causing all this?
When if ever were the spark plug boots checked/replaced as needed?
If you're not feeling a multiple-cylinder misfire and they're not setting confirmed codes that's highly curious.
When if ever were the spark plug boots checked/replaced as needed?
If you're not feeling a multiple-cylinder misfire and they're not setting confirmed codes that's highly curious.
FTE Community Team
Joined: Jan 2019
Posts: 10,739
Likes: 1,497
Hoping someone may have experienced a similar strange behavior checking cylinder misfires and could provide some explanation…
Following a break-down on my motorhome I started monitoring cylinder misfires and I’ve noticed a pattern to the random misfires. On three test drives about 60 miles. Using Torque Pro for mode06 info I finished up with a test results scan to retrieve the misfire information. On all three tests I had 5 cylinders with misfire counts. Each test drive had a different 5 cylinder combination. In all three test drives the number of misfires was either 64 or 65, or a multiple of 65.. i.e.; 3 cylinders @ 65, 1 @ 130 and 1 @ 260. Or another test returned 2 cylinders @ 64 and 3 @ 129, but so far always a total of 5 different cylinders reporting.
I’m beginning to wonder if there is an interference issue causing this. At no time do I “feel” the misfire.. all smooth running.
2003 Ford F53 motorhome chassis, 6.8 V10 35,000 miles
BAFX bluetooth OBD2 scanner ~ Torque Pro on Android tablet
Following a break-down on my motorhome I started monitoring cylinder misfires and I’ve noticed a pattern to the random misfires. On three test drives about 60 miles. Using Torque Pro for mode06 info I finished up with a test results scan to retrieve the misfire information. On all three tests I had 5 cylinders with misfire counts. Each test drive had a different 5 cylinder combination. In all three test drives the number of misfires was either 64 or 65, or a multiple of 65.. i.e.; 3 cylinders @ 65, 1 @ 130 and 1 @ 260. Or another test returned 2 cylinders @ 64 and 3 @ 129, but so far always a total of 5 different cylinders reporting.
I’m beginning to wonder if there is an interference issue causing this. At no time do I “feel” the misfire.. all smooth running.
2003 Ford F53 motorhome chassis, 6.8 V10 35,000 miles
BAFX bluetooth OBD2 scanner ~ Torque Pro on Android tablet
I'd check fuel pressure while this is happening. If it is getting low enough then it will run a little bit lean and could cause misfires.
FTE Community Team
Joined: Jan 2019
Posts: 10,739
Likes: 1,497
Remote possibility in my book.
I think this is a good path, especially on @Wmcrinc's 2003 model year V-10 that's been lugging a giant box around its whole life.
If the misfires are minor and random, the weight of the vehicle will often mask them with the added momentum and the higher engine speeds. The older 6.8s just about never run slowly while putting out power (as they sometimes get the opportunity to in pickups), and the weight of the motorhome won't slow as easily for misfires (masking the seat-of-pants feeling of misfires), especially when the higher engine speed is masking them.
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