Code P0300 Cylinder Misfire Detected (Lund E85R)

[blueskies925]

I down shifted hard (MT82), and all of a sudden power was cut from my engine and my CEL started flashing with the engine driving rough. Thought it could have been a dying battery, but my Ngauge says “Random/Multiple Cylinder Misfire Detected”
I reset codes and tried starting again, and it became very rough again so I shut it off right away.

Note: I am tuned by Lund on E85R.
Should I be worried this is something catastrophic? Any advice and help is appreciated thank you.

I also have a few different codes that previously showed up, but was never a bother again (P0017, P0015 camshaft position and timing). I’ve been on E85 for almost a year..

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[ice445]

I'd try a crank relearn and see if that corrects it

 

[Cory S]

Tighten plug gap a bit?

 

[TnWHTMARE]

"Downshifted hard"... can you explain that a little more? Mechanical over-rev?

 

[TexasMetallic5.0]

It doesn't take much to make the knock sensors wig out.

 

[blueskies925]

"Downshifted hard"... can you explain that a little more? Mechanical over-rev?

Yeah mechanical over-rev, but nothing close to redlining or anything.

I'm having the car checked out at a shop to locate the problem, hopefully it's not something serious.

 

[DivineStrike]

Yeah mechanical over-rev, but nothing close to redlining or anything.

I'm having the car checked out at a shop to locate the problem, hopefully it's not something serious.

You can’t mechanically over-rev and not be close to redline. Over-rev is simply exceeding redline lol

 

[blueskies925]

Well... Ford didn't do anything, just "cleared the codes" and it's driving fine now (even though I also cleared the codes in my nGauage but it still was rough idling/driving)? They said I was driving it too hard and the car went into limp mode. Not sure how some 4-5k rpm pulls and downshifts is hard, but okay. Anyways, I think I've made the decision to part with the car considering how the future is not clear with its reliability and now that I am out of warranty. So long Ford? Probably..

 

[LOL WUT]

Verified quality of E85?

 

[aedfam]

Well... Ford didn't do anything, just "cleared the codes" and it's driving fine now (even though I also cleared the codes in my nGauage but it still was rough idling/driving)? They said I was driving it too hard and the car went into limp mode. Not sure how some 4-5k rpm pulls and downshifts is hard, but okay. Anyways, I think I've made the decision to part with the car considering how the future is not clear with its reliability and now that I am out of warranty. So long Ford? Probably..

This is interesting. What did your tuner say? Any feedback from them?

 

[silverbullet85]

Not to be mean but it seems like you don't know enough about your car to be modifying it. How is it unreliable? You probably went from 4th to 1st and the computer went into limp mode. Unhooking the battery or doing a crank relearn or reflashing your tune would fix it.

 

[blueskies925]

Verified quality of E85?

Yup. My last fill (when it happened that I'm still on) was almost 90% alcohol percentage, but the previous one was 70%.

This is interesting. What did your tuner say? Any feedback from them?

They emailed me back saying:
"What does Ford say ? This tune you have is on thousands of cars so this is not normal

Engine could have bore scoring on the cylinder walls stemmed from Ford manufacturing to have misfires like this on a stock intake tune . Its not normal . Ford had had engine issues on early 18s "

Not to be mean but it seems like you don't know enough about your car to be modifying it. How is it unreliable? You probably went from 4th to 1st and the computer went into limp mode. Unhooking the battery or doing a crank relearn or reflashing your tune would fix it.

I've had this car for 3 years, I went from 3rd to 2nd lol. I have a MGW shifter, so those mis-shifts don't/can't really happen unless I want it to. I did a reflash of my tune and crank relearn after I got it back, we'll see. I drove it hard to test it right after, so far so good, but I'm not hopeful..

 

[aedfam]

Check your battery it could be you may need a new battery. My friend had a similar issue with tune not loading properly. During the load process of car turning on and off battery will drain and not complete the tune (his car would also die quickly and need a jump if he had the car key on for 5/10 min). He looked at his battery and saw it was leaking and figured it may could had been the tune not loading properly due to insufficient charge. He took it to Ford to get a new battery and get the stock tune loaded back from Ford. This is why when I'm loading a tune I hook a charger to the battery to make sure I don't lose voltage/charge during tuning cause it could lead to something worse.

Also I had another friend who had a similar issue after installing a new intake manifold. It was running rough and he was getting all kinds of codes and what it turned out to be was he forgot to put the gaskets in place so it had a vacuum leak. Maybe this could be a vacuum leak somewhere?

 

[blueskies925]

Check your battery it could be you may need a new battery. My friend had a similar issue with tune not loading properly. During the load process of car turning on and off battery will drain and not complete the tune (his car would also die quickly and need a jump if he had the car key on for 5/10 min). He looked at his battery and saw it was leaking and figured it may could had been the tune not loading properly due to insufficient charge. He took it to Ford to get a new battery and get the stock tune loaded back from Ford. This is why when I'm loading a tune I hook a charger to the battery to make sure I don't lose voltage/charge during tuning cause it could lead to something worse.

Also I had another friend who had a similar issue after installing a new intake manifold. It was running rough and he was getting all kinds of codes and what it turned out to be was he forgot to put the gaskets in place so it had a vacuum leak. Maybe this could be a vacuum leak somewhere?

Interesting you say that because I was already considering needing a new battery as my car recently keeps saying "system off to save battery" or something like that when I get in the car after several days of no driving. However, the voltage levels aren't that low, yet, but do seem to be fluctuating. It's something I will get checked out asap now too!

 

[Cory S]

Interesting you say that because I was already considering needing a new battery as my car recently keeps saying "system off to save battery" or something like that when I get in the car after several days of no driving. However, the voltage levels aren't that low, yet, but do seem to be fluctuating. It's something I will get checked out asap now too!

After 24 hours of sitting, your battery should read 12.45-12.6V at rest with no load.

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