Check engine light

[nickstobias]

Any guesses, just got a tune up last week , drove it last night all of a sudden car starting running rough exhaust tone got strangely louder, check engine light came on and flashed then went off as I kept it out of boost. Its at shop now, possible plug or coil issue? Owner said the plugs were gapped properly at 028

 

[13COBRA]

Who knows. Could just be bad gas.

 

[nickstobias]

Misfire in cylinder 8 heading compression test but he thinks it’s a nukedpiston,the funny thing is the car was running fine beforehand


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[SCGallo2]

Could be a coil pack not fully seated on the plug, loose spark plug blowout (unlikely), or loose coil pack connector if not reinstalled correctly. I take my time and pay close attention to detail when replacing my spark plugs. Check electrical and vacuum connections on your CAI and anything else removed during recent maintenance.

If cylinder damage, this would be your second hurt motor, right? A quality tune and fresh top-tier octane are essential for a happy engine. If fuel sits in my tank for over a month, I burn it all out and fill up with fresh Shell 93 octane before going WOT.

 

[nickstobias]

Yep, he says he thinks the piston is nuked. He says it’s a fuel issue. He said also because I put 373s in it because I’m getting on the car it’s making the car work harder and leaning it out.


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[nickstobias]

Which is odd because I’m not even getting on the car that hard with the new gears


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[2011 gtcs]

Yep, he says he thinks the piston is nuked. He says it’s a fuel issue. He said also because I put 373s in it because I’m getting on the car it’s making the car work harder and leaning it out.


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3.73s doesn't make the car work harder, if anything it makes it easier on everything. 3.08s would be a different story.

What all do you have done to the car? What fuel are you using? Sounds like your tuner didn't know what he was doing if you "nuked a piston"

 

[nickstobias]

Have had the same tune since 2018 with same mods Gen 2R stainless works Long tubes 67TB JLT all the usual parts was a conservative tune as well


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[nickstobias]

The car ran fine until I took it in for a tuneup after I took it in for a tuneup. That’s what the issue happened.


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[Bullitt1448]

The 3.73 thing is bullshit, he don’t want to pay for an engine so he’s looking to find an excuse you’ll swallow. 3.73 should help the car move easier not harder. If it’s a damaged piston odds are it was the tune, don’t let him alter the tune without you present would be my advice.

 

[nickstobias]

I just had him putting gears feel filter oil, change and spark plugs the performance tune and was in the car since 2018 and I’ve had no issues up until after this stuff was done


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[nickstobias]

It’s so bizarre that the car was running just fine but a week later after being in the shop this happens I didn’t notice when I got it from the shop that it was running. The idle was a little different, but I didn’t think anything of it. I thought the computer was adjusting to it.


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[Vinnie_B]

I would recommend finding someone who has access to FORD IDS to find this issue for your cylinder 8 misfire.

It can only be 3 things:

*Fuel Injector
*Coil/Bad Spark plug
*Cylinder Issue (Piston,Valve or cylinder)

Tests to run:


Misfire Test to confirm the cylinder



Fuel injector Test (Bad injector and/or electrical harness or PCM issue)



Cylinder Power Balance Test (How much each cylinder contributes. If the failing cylinder isn't fuel related run COP (Coil on plug) test to check for a faulty coil.



Compression Test (If a cylinder fails in this test confirm with a manual gauge compression and leak down test)




I've run these tests frequently for many customers. A qualified auto electrician should be able to have you answers on how and what failed in 5 hours or less.

 

[DSG2003Mach1]

Seeing how it felt off immediately after could be a coil didnt fully seat, connector was loose etc. I’ve done that to myself before

 

[nickstobias]

Picture of my plug


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[nickstobias]

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[DSG2003Mach1]

weeell ****, thats not good

 

[nickstobias]

Nope


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[1Kona_Venom]

**see other thread

 

[2011 gtcs]

View attachment 1836507


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I'd borescope that cylinder and see what's going on in there.