Any suggestions for this? I already changed plugs and coils but it keeps throwing this. Truck runs fine until around 55 to 60 mph.
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P0301 misfire
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Last: 16 days ago by fixer
What did plug look like? oily? Ashy? water or moisture on it?
Swap the coil with an adjacent one and see if the misfire stays on cylinder 1 or moves to adjacent cylinder.
(Seems like coil manufacturing, or re-manufacturing, is about as solid as lifter manufacturing these days.)
If it stays on cylinder 1 then thoroughly check the wiring and connector.
If connector and wiring are good then re-check spark plug. I've seen many times new plugs have cracked porcelain from being dropped in shipping and inventory. You will see carbon tracking on the porcelain. Look closely.
If plug and wiring are good after thorough inspection then you are into a compression test to see if there is a combustion chamber issue (valve, headgasket, rings).
EDIT: I have also seen the 'driver' module on an ECM fail to fire a coil and also another where it failed to fire an injector on one cylinder. This is rare. I would rule out engine mechanical issues befor going down this rabit hole. You'd be best to find a shop with good scope skills to check this particular failure mode.
If it moves to adjacent cylinder then try another brand of coil.
Swap the coil with an adjacent one and see if the misfire stays on cylinder 1 or moves to adjacent cylinder.
(Seems like coil manufacturing, or re-manufacturing, is about as solid as lifter manufacturing these days.)
If it stays on cylinder 1 then thoroughly check the wiring and connector.
If connector and wiring are good then re-check spark plug. I've seen many times new plugs have cracked porcelain from being dropped in shipping and inventory. You will see carbon tracking on the porcelain. Look closely.
If plug and wiring are good after thorough inspection then you are into a compression test to see if there is a combustion chamber issue (valve, headgasket, rings).
EDIT: I have also seen the 'driver' module on an ECM fail to fire a coil and also another where it failed to fire an injector on one cylinder. This is rare. I would rule out engine mechanical issues befor going down this rabit hole. You'd be best to find a shop with good scope skills to check this particular failure mode.
If it moves to adjacent cylinder then try another brand of coil.
Could also be an injector flaking out depending on engine.
Where'd you get the plugs/coils? Sadly new doesn't mean good these days - especially if the parts came from Amazon or eBay.
What year truck/engine?
What year truck/engine?
3.5 ecoboost. The plugs and coils are motor craft. I'll check the plug and wires again my next set off. Thanks
Check for hairline crack in ceramic on plug.
Different vehicle, but did a tune-up on our Polaris Ranger recently, new plugs, immediately getting misfire codes. Turns out the gap was almost none existent on one plug, so may be worth checking the spark plug gap as well.
On my 2014 5.0 it turned out to be a burnt exhaust valve...
Hope that's not the problem. We changed to plug and swapped the coil, sputters. The transmission had the lead frame changed about a year ago and hasn't ran as before since. It still gets around. Probably going to have to let it go.
Have you done. Cylinder contribution test and a compression test?
No sir I have not. Can you give me information on that. I'm pretty much a basic mechanic, not sure what all that involves.
southernboy1 said:
Hope that's not the problem. We changed to plug and swapped the coil, sputters. The transmission had the lead frame changed about a year ago and hasn't ran as before since. It still gets around. Probably going to have to let it go.
Are you getting the same P0301?
When you swapped the coil do you mean with another cylinder or did you replace it?
I only swapped it. The rest are good according to the obd.
Did code for misfire go to the cylinder you swapped with?
What vehicle? Try swapping coil, if code stays with that cylinder, try swapping fuel injector. If code stays on same cylinder it's not your coil or injector & probably an expensive fix.
No. It stayed on 1. I'm sure it's not the plug or coil at this point. I still need to inspect the wires, just waiting for the time.
Ok thanks for update.
Yeah check wires and connector very carefully.
While you are at it I would check the connector and wires on the associated injector.
So if this issue starts when hitting 55-60 mph then that is when the load on engine is increasing a fair amount , depending on gear.
This could be fuel delivery issue: injector, high pressure fuel pump, or in tank pump.
I would do a compression test to rule out engine issues.
Then you are looking at either swapping fuel injector or getting a scan tool that can check fuel pressure, cylinder balance and fuel injector test, as well as short and long term fuel trims.
Yeah check wires and connector very carefully.
While you are at it I would check the connector and wires on the associated injector.
So if this issue starts when hitting 55-60 mph then that is when the load on engine is increasing a fair amount , depending on gear.
This could be fuel delivery issue: injector, high pressure fuel pump, or in tank pump.
I would do a compression test to rule out engine issues.
Then you are looking at either swapping fuel injector or getting a scan tool that can check fuel pressure, cylinder balance and fuel injector test, as well as short and long term fuel trims.
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