2013 Roush Raptor misfire at higher levels of boost

wvaboy

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Before I take my baby to the shop........ any thoughts. There are no codes, It will not misfire in neutral and revving the engine, it will not misfire under light load.

It only misfires when boost gauge gets over 4. so from 5-7, gets worse and more violent as you get closer to 6-7. Can put in back in neutral rev all you want and everything is fine. So under any type of "heavy" load on engine it misfires no matter what speed. again throwing no codes and I have put several different gas refills in tank so it's not gas.

Anything to check first? Start with plugs and work out?
 

MTF

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My first concern would be,

Weak battery? Anything under 12.7 volts when truck is off is a NO GO!
Loose and corroded connections all the way down to the starter!!!!
The Roush SC will never need more fuel pressure than the stock fuel pump can deliver.
But I would check fuse #27
Have you done the TSB relocation for fuse 27?

Mass air flow sensor clean?
Check and tighten all intake tubes!!!
How many miles on the spark plugs?
What are they gap at?

Are you using the highest octane fuel you can find and do you trust them? but you tried a few places you stated.
Bad and/or cheap gas will do that!!!
If you think you may have gotten a bad tank full of gas,
I would run some ethanol enzyme fuel treatment and injector/full system cleaner.
I do this two to three times a year myself.

What heat exchanger do you have?
Heat, heat causes miss fires, check all fluids.
Check thermostat or use a colder one, I run a 170 and you don't need to change it for the winter months.
 
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CoronaRaptor

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My first concern would be,

Weak battery? Anything under 12.7 volts when truck is off is a NO GO!
Loose and corroded connections all the way down to the starter!!!!
The Roush SC will never need more fuel pressure than the stock fuel pump can deliver.
But I would check fuse #27
Have you done the TSB relocation for fuse 27?

Mass air flow sensor clean?
Check and tighten all intake tubes!!!
How many miles on the spark plugs?
What are they gap at?

Are you using the highest octane fuel you can find and do you trust them? but you tried a few places you stated.
Bad and/or cheap gas will do that!!!
If you think you may have gotten a bad tank full of gas,
I would run some ethanol enzyme fuel treatment and injector/full system cleaner.
I do this two to three times a year myself.

What heat exchanger do you have?
Heat, heat causes miss fires, check all fluids.
Check thermostat or use a colder one, I run a 170 and you don't need to change it for the winter months.
What fuel injector cleaner do you use, I've never done that yet and would like to start doing it :)
 

wvaboy

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My first concern would be,

Weak battery? Anything under 12.7 volts when truck is off is a NO GO!
Loose and corroded connections all the way down to the starter!!!!
The Roush SC will never need more fuel pressure than the stock fuel pump can deliver.
But I would check fuse #27
Have you done the TSB relocation for fuse 27?

Mass air flow sensor clean?
Check and tighten all intake tubes!!!
How many miles on the spark plugs?
What are they gap at?

Are you using the highest octane fuel you can find and do you trust them? but you tried a few places you stated.
Bad and/or cheap gas will do that!!!
If you think you may have gotten a bad tank full of gas,
I would run some ethanol enzyme fuel treatment and injector/full system cleaner.
I do this two to three times a year myself.

What heat exchanger do you have?
Heat, heat causes miss fires, check all fluids.
Check thermostat or use a colder one, I run a 170 and you don't need to change it for the winter months.
for sure not the battery or connections. have not relocated tsb for fuse 27, tbh not sure what that even does but i'll look into that.
77k on the plugs so that's where i'll be starting i guess and be sure they are gapped correctly. have never had any issues what so ever until this. 93 octane is the only gas that has ever been run in it.

under heavy pedal load, the truck does it at high boost only with and without being warm/cold so it's not a heat or thermostat issue
the only time it does it is at 5-7 boost. if i switch to neutral and rev the engine there is no issue what so ever no matter how high the rpms go.......only under load with boost. tuner says he believes it's probably plugs......or possibly a bad coil
 

moog5050

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for sure not the battery or connections. have not relocated tsb for fuse 27, tbh not sure what that even does but i'll look into that.
77k on the plugs so that's where i'll be starting i guess and be sure they are gapped correctly. have never had any issues what so ever until this. 93 octane is the only gas that has ever been run in it.

under heavy pedal load, the truck does it at high boost only with and without being warm/cold so it's not a heat or thermostat issue
the only time it does it is at 5-7 boost. if i switch to neutral and rev the engine there is no issue what so ever no matter how high the rpms go.......only under load with boost. tuner says he believes it's probably plugs......or possibly a bad coil
On my 2019, I was recently having intermittent misfires under heavy load. Changed plugs and gapped them. No more problems. Good luck.
 

bubblehead93

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On my 2019, I was recently having intermittent misfires under heavy load. Changed plugs and gapped them. No more problems. Good luck.
This, common 03-04 Cobra issue, too much gap, hence only under boost... I'm sure there is some supercharged Raptor tribal knowledge... but if you are running the factory gap on your plugs in a supercharged application... likely the problem... you want the most gap you can get away with without the boost blowing out the spark (figuratively)... if you are only seeing it on one cylinder, then it could just be that plug or coil...
 
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