CEL flashing
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Trailering
Joined: Jul 2023
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CEL flashing
I have the 2017 F250 6.2l 110,000 miles
So I have changed all 16 plugs, wires & boots. I previously was getting the p0301 or p0305 code. So I had it looked at by a local reputable shop, he said variable misfire and suggested to replace all of the coil packs ughhhh 110,000 miles, really..... so I bit the bullet $800 later (OEM FOMOCO coils), I have driven it about 350 miles no CEL "yet"
But weird deal.
so the truck really only purpose is to pull my jayco camper. It is not a daily driver. Camper is 10,500lbs. I was pulling this past weekend and was climbing a good hill, tranny downshifted to about 3rd gear was running about 55-60mps. The CEL started flashing, as soon as I crested the hill, got off the throttle, about 10 sec later it stopped flashing. This happened to me a total of 4 times, once there and 3 times returning. Each time was when I was going heavy on throttle, uphill. I looked at a few forum posts, nothing conclusive yet. I do know that a flashing CEL isn't good. It generally means a cylinder is dumping raw fuel into catalytic converter.. The CEL has not illuminated steady on, thankfully. I have not had the OBD2 read as of yet. But the CEL is not illuminated.
Any idea, or has this ever happened to any of you. SO frustrating..... I really don't want to take it to dealer. But I need a reliable truck to pull my camper.
Mike
So I have changed all 16 plugs, wires & boots. I previously was getting the p0301 or p0305 code. So I had it looked at by a local reputable shop, he said variable misfire and suggested to replace all of the coil packs ughhhh 110,000 miles, really..... so I bit the bullet $800 later (OEM FOMOCO coils), I have driven it about 350 miles no CEL "yet"
But weird deal.
so the truck really only purpose is to pull my jayco camper. It is not a daily driver. Camper is 10,500lbs. I was pulling this past weekend and was climbing a good hill, tranny downshifted to about 3rd gear was running about 55-60mps. The CEL started flashing, as soon as I crested the hill, got off the throttle, about 10 sec later it stopped flashing. This happened to me a total of 4 times, once there and 3 times returning. Each time was when I was going heavy on throttle, uphill. I looked at a few forum posts, nothing conclusive yet. I do know that a flashing CEL isn't good. It generally means a cylinder is dumping raw fuel into catalytic converter.. The CEL has not illuminated steady on, thankfully. I have not had the OBD2 read as of yet. But the CEL is not illuminated.
Any idea, or has this ever happened to any of you. SO frustrating..... I really don't want to take it to dealer. But I need a reliable truck to pull my camper.
Mike
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From: Stephensville WI
It honestly could be one of seventy five different issues. Get a code reader and find out what codes have been stored. Doing anything else at this point is a waste of money.
Incidentally, any shop that tells you to replace all 16 coils because of a variable misfire is not a “reputable shop.” I hope they didn’t charge you much for that bad advice.
Incidentally, any shop that tells you to replace all 16 coils because of a variable misfire is not a “reputable shop.” I hope they didn’t charge you much for that bad advice.
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Trailering
Joined: Jul 2023
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thx for the quick response.
Regarding the shop, I have used them for several years for different vehicles. Always fair upfront w/ needed repairs. I have been to "bad shops " before. So I was ok w/ the dx. I was in fact having misfires and it was random. I had previously tried swapping coils to isolate the issue. If I had to replace a coil, I guess my thinking was at least they will remain consistent. I saved the old coil packs and labeled them at to which cylinder they were on. He tested the fuel pressure at the time and indicated no issues w/ low fuel pressure at the injectors. also no issues w/ O2 sensors. I agree there are so many potential issues. But without the CEL being illuminated, I wasn't sure if a code would be stored, just from the flashing CEL.
\
Mike
Regarding the shop, I have used them for several years for different vehicles. Always fair upfront w/ needed repairs. I have been to "bad shops " before. So I was ok w/ the dx. I was in fact having misfires and it was random. I had previously tried swapping coils to isolate the issue. If I had to replace a coil, I guess my thinking was at least they will remain consistent. I saved the old coil packs and labeled them at to which cylinder they were on. He tested the fuel pressure at the time and indicated no issues w/ low fuel pressure at the injectors. also no issues w/ O2 sensors. I agree there are so many potential issues. But without the CEL being illuminated, I wasn't sure if a code would be stored, just from the flashing CEL.
\
Mike
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Only codes that are immediate issues set the CEL, but other codes that clear up do not set a CEL but are stored in keep alive memory, KAM.
Hate to say this, but hard acceleration like going up a hill with a misfire can trigger what you see. It is possible you are still getting a misfire. With new coil packs, insulators and plugs, that leaves a bad injector, or bad wiring to the coil packs.
Hate to say this, but hard acceleration like going up a hill with a misfire can trigger what you see. It is possible you are still getting a misfire. With new coil packs, insulators and plugs, that leaves a bad injector, or bad wiring to the coil packs.
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Trailering
Joined: Jul 2023
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Only codes that are immediate issues set the CEL, but other codes that clear up do not set a CEL but are stored in keep alive memory, KAM.
Hate to say this, but hard acceleration like going up a hill with a misfire can trigger what you see. It is possible you are still getting a misfire. With new coil packs, insulators and plugs, that leaves a bad injector, or bad wiring to the coil packs.
Hate to say this, but hard acceleration like going up a hill with a misfire can trigger what you see. It is possible you are still getting a misfire. With new coil packs, insulators and plugs, that leaves a bad injector, or bad wiring to the coil packs.
Cargo Master
Joined: Aug 2003
Posts: 3,263
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From: BC Canada
putting aside the poor advice you received, of replacing ALL Coils and plugs, I would have done 2 tests:
Connect a scope and investigate the coil and injector ramps, check the fuel trims at speed, loaded. Lets get some true DATA.. no guessing..
A flashing CEL is indicative of a miss fire which may cause damage to the emissions (CAT)
Connect a scope and investigate the coil and injector ramps, check the fuel trims at speed, loaded. Lets get some true DATA.. no guessing..
A flashing CEL is indicative of a miss fire which may cause damage to the emissions (CAT)
Lead Driver
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Thx for the response. Regarding bad wiring, you know I knew I had a misfire on #1 because I would at times hear an obvious ticking (arcing sound), the sound of an arc. I popped the hood one night, and actually saw the blue spark arcing from the connector to a nearby piece of metal. I have seen and heard this 2 times. this is what made me decide to go ahead and change the coils. I was definitely thinking it was a defective coil causing the arc. Now, I am truly wondering if this is in fact a bad wire connector. I sure would like to be able to test for that. Any Ideas of how I can troubleshoot to see if it does have a sporadic arc?
Get a spray bottle filled with water and mist the coils, wiggle the wires while at it. You will know which one is bad when it starts to misfire due to a bad wire harness. The alternative is if you want to do it yourself is to buy a scan tool to do like suggested above. I bi-directional one can be had for under $500 on Amazon, Launch 431 is a decent tool but takes time to understand how to use it. I bought one and have saved several hundred $ in doing my own diagnostics.
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Trailering
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Get a spray bottle filled with water and mist the coils, wiggle the wires while at it. You will know which one is bad when it starts to misfire due to a bad wire harness. The alternative is if you want to do it yourself is to buy a scan tool to do like suggested above. I bi-directional one can be had for under $500 on Amazon, Launch 431 is a decent tool but takes time to understand how to use it. I bought one and have saved several hundred $ in doing my own diagnostics.
I had a cheap one, that petered out. It would at least point me in right direction.
I was actually looking to purchase another one, as I generally diy all of my auto repairs/maintenance.
I'll definitely look into this one, so "bi-directional" is what I need to be looking for?
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TYPICALLY a flashing CEL is an active misfire situation. It doesn't always.
Regardless, before doing any more repairs a check of what codes are stored is imperative.
At 110k miles on a coil-on-plug motor, it's very possible the coils were going bad, but it is ALSO possible you got ANOTHER bad coil, especially if you didn't go with performance or OEM coils.
If you saw an arc at one of the coil's connectors, that would have been the 1st place to start - either the connector is bad or the wiring is bad, and needs to be repaired. A quick test would be to wrap the area that was arcing in electrical tape or dab some dielectric grease on it and see if the problem goes away.
Regardless, before doing any more repairs a check of what codes are stored is imperative.
At 110k miles on a coil-on-plug motor, it's very possible the coils were going bad, but it is ALSO possible you got ANOTHER bad coil, especially if you didn't go with performance or OEM coils.
If you saw an arc at one of the coil's connectors, that would have been the 1st place to start - either the connector is bad or the wiring is bad, and needs to be repaired. A quick test would be to wrap the area that was arcing in electrical tape or dab some dielectric grease on it and see if the problem goes away.
Thread Starter
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Trailering
Joined: Jul 2023
Posts: 17
Likes: 2
TYPICALLY a flashing CEL is an active misfire situation. It doesn't always.
Regardless, before doing any more repairs a check of what codes are stored is imperative.
At 110k miles on a coil-on-plug motor, it's very possible the coils were going bad, but it is ALSO possible you got ANOTHER bad coil, especially if you didn't go with performance or OEM coils.
If you saw an arc at one of the coil's connectors, that would have been the 1st place to start - either the connector is bad or the wiring is bad, and needs to be repaired. A quick test would be to wrap the area that was arcing in electrical tape or dab some dielectric grease on it and see if the problem goes away.
Regardless, before doing any more repairs a check of what codes are stored is imperative.
At 110k miles on a coil-on-plug motor, it's very possible the coils were going bad, but it is ALSO possible you got ANOTHER bad coil, especially if you didn't go with performance or OEM coils.
If you saw an arc at one of the coil's connectors, that would have been the 1st place to start - either the connector is bad or the wiring is bad, and needs to be repaired. A quick test would be to wrap the area that was arcing in electrical tape or dab some dielectric grease on it and see if the problem goes away.
so i did replace the coils w/oem motorcraft coils. along with motorcraft wires, boots, and plugs.
At least 2x I saw a strong blue arc from coil #1, also the obvious arcing sound.
The electrical tape and dielectric Grease are good options.
I had a cheapo code reader, am looking at a good quality reader, as I am typically a diy repair person,if it is something I can handle, on all of my vehicles.
thx again
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