katleman
San Mateo
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Been up in Alaska all summer, my 2016 E450 Ford V10 (26,000 miles) has had the CEL on for the past five weeks. According to my OBD2 scanner, it first started throwing P0300 (generic misfire), then it claimed cylinder 2 was the culprit (P0302)
Replaced the air filter as it was filthy. Nope.
At the point its flagging 4 different cylinders, split between the two sides, had a mechanic diagnose it, suggested bad fuel or water. Tossed in SeaFoam and iso Heat. Nope
Refusing to believe it’s the plugs/coils on 4 cylinders, as they are good for 100k miles, tried replacing the MAF sensor. Nope.
Bit the bullet and replaced all the plugs and coils. Nope.
All through this period of misfires, which was flashing the CEL once a mile, no loss of power, no loss of fuel economy, drove just as it always has.
So I’m heading homeward with the CEL flashing, run out of things to check or replace. Stumped every mechanic I have consulted.
* This post was
edited 08/20/23 11:07pm by katleman *
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zigzagrv
Nazareth, PA
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Did you check your battery voltage? Had a similar situation once where after I would stop for a short while and when restarted, it would run rough and throw codes till I got up to speed. Turned out battery was bad and till the alternator built up voltage, this would happen. New battery solved the problem.
Ron
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katleman
San Mateo
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zigzagrv wrote:Did you check your battery voltage? Had a similar situation once where after I would stop for a short while and when restarted, it would run rough and throw codes till I got up to speed. Turned out battery was bad and till the alternator built up voltage, this would happen. New battery solved the problem.
Battery is new this season, replaced proactively, not out of need.
The codes are thrown at idle, up hills, down hills, doesn’t appear to vary with load.
* This post was
edited 08/21/23 08:37am by katleman *
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Grit dog
Black Diamond, WA
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^Very frustrating when competent diagnosis fails. Good news is it runs just fine I suppose.
Your rig is new enough that chaffed wires, corrosion etc are lower on the list of possible causes, but if there’s any areas on the injector, coils and or main ECM harness you haven’t checked, including unplugging all harnesses and just looking for visual damage to the pins or connections, that’s where I’d likely go next.
And it’s not out of line that you may have picked up a furry traveler along the way who likes multicolored licorice (wire insulation) or spent a night or 2 in pack rat country and they snacked on some wires.
If you have camped where it looks like everyone is working on their engines (hoods up), they’re not. You’re in packrat country. And those things are pure evil to vehicles and other things.
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bobndot
USA
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CEL can light-up due to a bad or dirty electrical connection from the ECU to the sensor.
My mechanic always checked that at my service intervals.
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katleman
San Mateo
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bobndot wrote:CEL can light-up due to a bad or dirty electrical connection from the ECU to the sensor.
My mechanic always checked that at my service intervals.
And specifically throw only cylinder misfire codes (P0300 & P030X), no other codes?
We’re talking once a mile or so.
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Krusty
Calgary, Alberta,Canada
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katleman wrote:bobndot wrote:CEL can light-up due to a bad or dirty electrical connection from the ECU to the sensor.
My mechanic always checked that at my service intervals.
And specifically throw only cylinder misfire codes (P0300 & P030X), no other codes?
We’re talking once a mile or so.
Check and make sure the center bolt holding your harmonic balancer on has not come loose
Krusty
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Valpo Camper
Valpo, Indiana
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Well I can do quite a bit under the hood of a car but this job kicked my butt and humbled me to applying the credit card wrench to it. 3 different cylinders were misfiring plus random misfire code is what the shop came up with. Replaced all 10 plugs and coils and did a fuel system cleaning. Runs like a big heavy smooth box again.
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opnspaces
San Diego Ca
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Sometimes you just gotta bite the bullet. But at least it's fixed. Now on to life's other adventures.
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