High Mileage!!!!!! code P0300, help

[Christang.GT]

So I have 95k miles on my 2015 Mustang GT PP1, I recently had a check engine light come on an I plugged it in to see what it was and threw up P0300. Now I should also mention that a few weeks ago the code for the canister purge valve came up (P1040 I think) I cleared it but it came back a few days later. Then I decided to just replace the valve with a new one, I installed it and the light was on, I figured it was for the same reason so I didn't bother to check until today. That's when I saw the P0300. I have RELIGIOUSLY done my services and taken good care of my car for the miles it has, its basically stock with only an x pipe and muffler delete but that's been done since 28k miles. I've changed the plugs at 30k, 50k and 70k with NGK. I've done all my oil changes when the car tells me too or if I drive it hard more than usual. I changed my trans fluid, diff fluid, flushed the cooling system (as best I could). Yeah so long story short I'm worried this time it's serious. I was hoping to drive this car till the wheels fell off or even say F it and upgrade some slight internals and go for a engine rebuild to go for a 500 WHP NA car but now I'm afraid it might die. Please help!!!!!!!

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[robwlf]

ive heard theres a runner in the intake manny that can sometimes go causing miss fire codes on multi cyl.. did you clear the code after you replaced the purge valve?

 

[Christang.GT]

ive heard theres a runner in the intake manny that can sometimes go causing miss fire codes on multi cyl.. did you clear the code after you replaced the purge valve?

No, not instantly. That is why I figured it was the purge valve, but I have cleared it now and it hasn't came back, I let drove the car around let it get up to temp and beat on it a bit and nothing, as smooth as butter? then it came on blinking but goes away. When it threw the 1450 code it had also said the purge line was wonky, I didn't replace that, but thats what I am about to do.

 

[robwlf]

yeah id replace that then see whats up .. i know if the runner goes the car will run like crap mostly all the time ,and throw miss fire codes again and again

 

[usgiorgi]

Does it stutter/jerk under very light throttle between 1800 and 2200 rpm? If so, I'm betting it's your runner control valves in the intake manifold like robwlf said.

 

[Christang.GT]

Does it stutter/jerk under very light throttle between 1800 and 2200 rpm? If so, I'm betting it's your runner control valves in the intake manifold like robwlf said.

Okay update, I haven't touched anything and the check engine light went away and the car runs smooth and no stuttering of any kind or power loss at all. BUT when I push it hard the check engine light blinks and it stayed on so I got it checked and it threw it again, Random misfire. I cleared it and nothing again. Runs smooth, drives great so I'm confused on what to do next. Has anyone else had this issue?

 

[Kane]

Okay update, I haven't touched anything and the check engine light went away and the car runs smooth and no stuttering of any kind or power loss at all. BUT when I push it hard the check engine light blinks and it stayed on so I got it checked and it threw it again, Random misfire. I cleared it and nothing again. Runs smooth, drives great so I'm confused on what to do next. Has anyone else had this issue?

Did you find the issue & resolved it?

 

[Skye]

Did you find the issue & resolved it?

The OP was last seen three and a half years ago. While there's hope they are lurking and could reply, you could start a thread with your details. Or bump this one, describing the problem you're having.

 

[Cobra Jet]

A random code like the P0300 is a PIA and no one on here would be able to give you a definitive "it's this part".

However, here's some things you can check:

Check the connector at the MAF and make sure it's totally secured. Make sure you don't have any breaches along the air intake track, or any cracks damages to the intake. Any such breach before or after the MAF is a vacuum issue and will skew signals for incoming air flow monitoring.

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Pull the plugs and post images of what you find for their readings/condition.

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- VCT solenoids - if the solenoids are not operating properly due to debris or they are failing due to age, they can cause such codes. Quite a few threads on here about these prematurely failing and/or how to diagnose.

The culprit here was the VCT solenoid::
https://www.mustang6g.com/forums/th...s-and-cam-retarded-codes.176734/#post-3571964

Here's (2) more threads for VCT info that I had previously posted in other threads:
https://www.mustang6g.com/forums/threads/2015-2021-s550-5-0’s-ssm-50067-vct’s-again-various-dtc-codes.169419/

https://www.mustang6g.com/forums/threads/p0018-code.123932/

- Crank sensor - failure can be the sensor itself, the harness to it or the pins in the connector. If the crank sensor is failing, it also will throw various misfire DTCs. The only time the crank sensor will throw a specific crank DTC is if the sensor is disconnected or it has completely failed. Many have found even with a generic misfire P0300, that the issue was related to the crank sensor. These sensors do not last forever due to their location and under hood heat cycles.
Check this thread:
https://www.mustang6g.com/forums/threads/misfire-at-high-rpm.174380/#post-3531453

AND this one:
https://www.mustang6g.com/forums/th...e-sensor-tone-ring.156234/page-2#post-3197692

The IMRC design has been problematic since the IMRC intake system first debuted in the 1994 Lincoln MKVIII with the 4.6 DOHC (which was then carried into the 1996 Cobra and beyond). Theres MANY threads on here regarding the intake and IMRC system.
https://www.mustang6g.com/forums/threads/possibly-broken-imrc-shaft.183221/#post-3689879

Clutch pedal or brake pedal bumpers deteriorated or missing. It’s a known issue, Ford issued a. NHTSA recall and if either is deteriorated or missing it will cause non-start or drivability issues with the car.
https://www.mustang6g.com/forums/th...edal-bumper-nhtsa-recall.172153/#post-3670904

and
https://www.mustang6g.com/forums/threads/brake-light-switch-near-pedal-failure.122100/

As far as the crank relearn do that again exactly as noted (some people have had to do it 2 or 3x) as well as trying KAM reset too. Here’s a thread I had with details of the crank relearn and KAM resets.
https://www.mustang6g.com/forums/threads/engine-misfire-problems.203556/#post-4075889

Hope something above was helpful.

 

[Kane]

It was crank relearn... I did it 3 times just in case.

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