intermittent misfire

[Thatguy6627]

my 2017 mustang gt manual has a misfire on 2 and 4 only under certain load conditions usually during hard driving. If i hold it anywhere above 3000 rpm for more then 30 sec or so well driving the misfire appears. If i continue to drive the same it goes away usually after about 30 secs or so if i let the rpms fall by either pushing in the clutch or by shifting into a higher gear it happens slightly fast usually without hard setting the cel and if it does set it most of the time the next time i start it its gone. this is what i have tried so far i moved coil packs and injectors to different cylinders and it consistent on 2 and 4 not sure what the next step is Please help

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[ORRadtech]

Milage, mods, tune, vehicle history???
Random, though this isn't really, misfires can be so many things that saying you've switched coil packs and injectors tells us nearly nothing.
Have you at least pulled the plugs and compared/checked condition?

 

[Ramairetransam]

try a crank relearn

 

[coyote550]

What are the codes exactly? Just the misfire or something else with it? Any crank/cam related codes by chance?

 

[Ramairetransam]

I had a miss that was wot only above 100 on a bone stock 18+ . Tried 87 and 93 and hot weather and cold weather. Always a flashing cel for a p0300. Then bought a sct and crank sensor. Did the crank relearn first and it solved the issue.

 

[Thatguy6627]

the motor got replaced under warranty about 6000 miles ago. the car has 82000mi on it. i have checked and replaced plugs in those holes. i have the ford power pack 2 on it which is the gt350 cold air and throttle body with the ford tune and a x pipe. have also done the crank relearn multiple times and it stops it for about 300 miles then it starts again

 

[Thatguy6627]

p302 and 304 codes

 

[coyote550]

Try replacing the crank sensor and doing a relearn again. Might be a faulty sensor. Also, test the compression on those two cylinders and compare it to the others.

 

[Thatguy6627]

So i replaced the crank sensor and did a relearn no change. Also pulled the plugs all are comparable well i had them out did a compression test just to eliminate that as a possibility all were within 2psi of each other with an average of 210psi

 

[drive_55_not]

Look for vacuum leaks ...

Did you get a new intake with the engine change or did they reuse to old one?


.

 

[Thatguy6627]

They reused they intake i will check for a vacuum leak

 

[Cobra Jet]

The easiest thing to have done would be swap coil packs with another cylinder you know has no issues. That would determine if you have a bad coil pack (which is common)…. Because if for instance the issue resolved on 3 but was now present on 5, that wouid point to a failing coil pack.

Throwing parts at the car is not a way to solve an issue without properly diagnosing.

Have you pulled the plugs to read them?

 

[ZLwhat]

Did this guy ever fix his issue?

 

[TonyT930]

my 2017 mustang gt manual has a misfire on 2 and 4 only under certain load conditions usually during hard driving. If i hold it anywhere above 3000 rpm for more then 30 sec or so well driving the misfire appears. If i continue to drive the same it goes away usually after about 30 secs or so if i let the rpms fall by either pushing in the clutch or by shifting into a higher gear it happens slightly fast usually without hard setting the cel and if it does set it most of the time the next time i start it its gone. this is what i have tried so far i moved coil packs and injectors to different cylinders and it consistent on 2 and 4 not sure what the next step is Please help

Im thinking start with spark plugs and then coil packs especially if your vehicle has higher mileage

 

[ZLwhat]

Im thinking start with spark plugs and then coil packs especially if your vehicle has higher mileage

What if those have both been replaced?

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