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Old 10-29-2022, 02:35 AM   #1
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Model: Miramar 34.1
State: Arkansas
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THOR #6634
Random/Multiple cylinder misfire detected.

On my 2017 Miramar 34.1 with the Ford Triton V10, I got a Steady (not blinking) Check Engine Light. I hooked it up to a cheap code reader and discovered there were 3 “Random/Multiple cylinder misfires” and one “cylinder 3 misfire” messages stored in my computer.
The light came on while pulling a sizable hill at 65 mph at around 4400 rpm’s
The rig had been running smoothly before the code and continued to run smoothly afterwards. The gauges on the dash were all in good shape. I was 16 miles from my destination so I backed down on the speed and rpm’s and drove in. Other that the troubling light, I could see or hear nothing to indicate a problem. The RV has 27,000 miles and was fully serviced in March.
I was driving an elderly couple to a doctors appointment 3 hours from our home. They, as planned, are staying in a hotel tonight while I’m sleeping in the RV. I need to get this couple home tomorrow but don’t want to damage to my rig. Am I safe to do so?
Thanks
Hugh Chapman

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Old 10-29-2022, 02:56 AM   #2
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I would think with a misfire, you’d know it. Engine miss. Sputter. I’d drive em home.
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Old 10-29-2022, 03:04 AM   #3
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Model: '17-Vegas 24.1
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Sounds to me like “bad gas”
Or
Unsealed gas cap causing a rare mis-fire

I have experienced similar check engine light symptoms on my E450 V-10 when it had abt 12k miles on the clock. Then again at 15k.
Both times at the next stop I removed gas cap & re-tightened.

Both times the check engine light eventually went off after several cycles.

If yours continues to cause problems you probably have no choice but to take to a Ford chassis service repair (dealer or independent)
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Old 10-29-2022, 03:30 AM   #4
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Originally Posted by Jimbo56 View Post
I would think with a misfire, you’d know it. Engine miss. Sputter. I’d drive em home.
Not necessarily with the V10.

I had a similar issue but my misfire was on cylinder 5 (if I remember right). The random multiple misfire is likely generated by just that dingle cylinder as the ECU can not always tell which cylinder is misfiring on the V10 due to the small angular difference between the cylinders..

Between the time I got the first P305 code and when I finally resolved it, I drove the MH probably 500 - 600 miles, clearing the code frequently. It's a miss, not likely to damage the engine unless due to a mechanical issue. Mine was too infrequent and random to be mechanical.

What I found was a rusted spark plug. There is a heater hose transition above the spark plug well that had been broke by Thor during construction and not put back together right some it had a minor coolant drip that collected in the spark plug well. Enough rust and corrosion on the plug and the spark would jump to ground on the outside of the porcelain under load. Replaced the plug, cleaned the well and fixed the leak. No problems since.

You may have a similar issue or maybe a bad coil. Clear the code, swap coils with the neighboring cylinder, drive home and see if the code comes back or does it change cylinders. Do additional troubleshooting/repair at home.
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Old 10-29-2022, 04:06 AM   #5
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THOR #6634
Thanks everyone. One additional question. I read on another board that on the 2017 models the spark plug wires were not heavy enough and would sometimes throw false codes. Has anyone else heard of this?
At any rate, I’m feeling better about tomorrows trip home. Thanks again!
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Old 10-29-2022, 04:20 AM   #6
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I would clear the code and drive home. If the money light comes back on, swap the coil for the affected cylinder with another cylinder and clear the code. If the light comes back with the same cylinder, change the plug. If it moves to the other cylinder, change the coil. If the money light comes back after all that, you will need further diagnostics from a qualified auto tech. I doubt it is the gas cap. On my last trip, I somehow forgot to put the gas cap on at a fuel stop. Senior moment, I guess. Anyway, when I stopped for the night and went to hook up the electric, I noticed it off. During the drive, the coach ran fine and had no lights on the dash.
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Old 10-29-2022, 04:55 AM   #7
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Originally Posted by Moondoggie View Post
Thanks everyone. One additional question. I read on another board that on the 2017 models the spark plug wires were not heavy enough and would sometimes throw false codes. Has anyone else heard of this?
At any rate, I’m feeling better about tomorrows trip home. Thanks again!
Spark plug wires? They're COPs - Coils On Plugs.
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Old 10-30-2022, 01:48 AM   #8
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Hey thanks everybody. I got my friends home today without a hitch. I just cleared the codes and tried to keep a lighter foot, especially on the big hills.
I’ll still be searching for the exact cause of the codes, but in the meantime, I’m happy with the way the rig is performing.
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Old 10-30-2022, 03:40 AM   #9
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I had the same issue with my 2016 Miramar when towing. I found it always happened when using the cruise and just letting the engine rev pulling hills and downshifting rather than braking.

I stopped using cruise when towing and generally drive in a way to keep the rpms below about 3,000. I haven't had an issue in 3 years since changing my driving habits.
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Old 10-30-2022, 02:09 PM   #10
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Years ago, on a 1996 Allegro on a Chevy P30 chassis I had a similar problem. The engine would misfire and backfire through the throttle body during acceleration and hill climbing. The problem ended up being the sparkplug wires. I also replaced the distributer cap and rotor. Once I replaced them the problems when away. Yes, I know the Ford V10 does not have a distributer. FWIW the cheapest thing you can do after resetting the code is to replace the SP wires.
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Old 10-30-2022, 02:50 PM   #11
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Quote:
Originally Posted by Moondoggie View Post
On my 2017 Miramar 34.1 with the Ford Triton V10, I got a Steady (not blinking) Check Engine Light. I hooked it up to a cheap code reader and discovered there were 3 “Random/Multiple cylinder misfires” and one “cylinder 3 misfire” messages stored in my computer.
The light came on while pulling a sizable hill at 65 mph at around 4400 rpm’s
The rig had been running smoothly before the code and continued to run smoothly afterwards. The gauges on the dash were all in good shape. I was 16 miles from my destination so I backed down on the speed and rpm’s and drove in. Other that the troubling light, I could see or hear nothing to indicate a problem. The RV has 27,000 miles and was fully serviced in March.
I was driving an elderly couple to a doctors appointment 3 hours from our home. They, as planned, are staying in a hotel tonight while I’m sleeping in the RV. I need to get this couple home tomorrow but don’t want to damage to my rig. Am I safe to do so?
Thanks
Hugh Chapman
You could just replace the coils to be safe, when an engine misfires raw gas is dumped into the catalytic converter, Catalytic converters usually run at 1200 to 1600 degrees Fahrenheit. Raw fuel in the presence of oxygen will cause the converter catalyst to overheat and melt
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Old 11-02-2022, 08:28 PM   #12
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I had the same problem with check engine light and other than check engine light did not notice the misfire. Found out I had a critter living on engine block over the winter and had chewed 2 of the wires leading to fuel injectors luckily the Mechanic had a couple of these off another vehicle and haven't had a problem since.
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Old 12-04-2022, 07:53 PM   #13
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What’s a good code reader for v10s?
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Old 12-04-2022, 08:24 PM   #14
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Originally Posted by Chipper10 View Post
What’s a good code reader for v10s?
V10 is not a code reader selection criteria. All code readers use the OBD2 interface in all autos since the late 90s. Codes are easy to read with the cheapest code reader, but how they interpret those codes, and other functions such as initiating diagnostics, displaying real time data, and changing settings is where the differences lie.

Other criteria may include Phone-Based interface vs stand-alone interface, wired vs wireless (bluetooth), and WIFI connection to the Internet. Of course features come with a price. "Code Readers" can range from under $20 to over $3000.

So, narrow your wish list and you'll probably get some good recommendations.
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Old 12-04-2022, 11:09 PM   #15
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What’s a good code reader for v10s?
I have a low priced Blue driver and it worked great and give you information on what it thinks is wrong. I also have a Innova that is around 300 dollars, it also allows you to subscribe and find out what's wrong
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