488 GTB Misfire at WOT High RPM – Seeking Ferrari Expertise

I recently picked up a 488 GTB, and I’m chasing a gremlin that’s got me stumped. I own Firepunk LLC, a diesel performance shop with a chassis dyno, so I’m no stranger to diagnostics and tuning—diesels are my wheelhouse. That said, the Ferrari platform is new to me, and I need some 488-specific expertise to steer me toward the next steps for diagnosing and fixing this issue.
The Problem:
The car runs and drives perfectly—smooth as silk—except under a hard WOT pull. After a few seconds at full boost, I get a misfire. It’s stock except for catless Capristo downpipes and a full exhaust.
What I’m Seeing:

• WOT runs shifting at 6500 RPM? Flawless, no hiccups, holding 20 psi boost.
• Let it auto-shift at 7500 RPM? Misfire hits between 6500-7500 RPM, CEL blinks, and I’ve pulled misfire codes for cylinders 3, 5, and 7 (P0303, P0305, P0307) on separate runs.
• My Launch scan tool shows knock detected via the ION module during these events.
• Bank 2 MAF readings are consistently lower than Bank 1.

Steps I’ve Taken:

• Boost Leak Check: Pressurized the intercooler system to 5 psi with a fog machine—no leaks. I’m confident there’s no major boost leak, unless something is developing at 20psi I don't see at 5psi
• Spark Plugs: Swapped in fresh OEM-spec plugs.
• Air Filter: Installed a new high-flow BMC filter.
• MAF Sensors: Swapped Bank 1 and Bank 2 sensors—lower readings stayed with Bank 2, so the sensors aren’t the issue.
• Turbos: Pulled the intake elbows—wheels look clean, no shaft play, no housing contact.
• Burned 400 miles of Gas through to make sure I have fresh 93 Octane I'm running

My Thoughts:
I initially figured a boost leak was causing a lean condition, triggering knock and misfire. The 5 psi test says otherwise, but I’m open to ideas. I’m wondering if this could be bad coil packs, an ION module quirk, or something tied to the catless exhaust. I’ve got the tools and know-how to dig deeper, but I lack the Ferrari experience to pick the right path.
Any 488 gurus out there who can point me in the right direction? I’d love some insight on what to check next—whether it’s dyno data, fuel system, or something else entirely. Appreciate the help!

https://photos.app.goo.gl/tDPneutxJuuHny7HA This is a link to a video of a hard pull, it pulls perfect the first two gears, the third gear shift/full boost is where I feel/hear the misfire.
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I swapped Mass Air Flow on the intakes Left to Right and nothing changed.
Here's the readings I have on Lambda
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I had it tuned by Matt at HD Tuning, He also returned the ECU to stock for me to confirm its not tuning related and the problem still exists with the OEM tune and I get Catalyst codes without the tune because of the catless downpipes.

Rail pressure follows commanded pressure perfectly, had that problem on my 458 so I feel confident the high pressure pump is holding rail.

 

what is involved in pulling injectors and cleaning, is it a surface/carbon build up cleaning or more involved? Is there any way to dianose whether that is the problem before digging into the project?

 

ok, thanks for your insite. I'm in central Ohio. Do you know a recommended fuel system shop that would be familiar with this platform in my area?

 

Would the ION module cause this misfire without throwing any fault codes pointing to the ION module?

 

Is there any way to determine if my problem is in the OIN module or whether its in the injectors? Noone has suggested a Coil issue, i'm assuming if a coil is bad, its bad, and wouldn't only cause a problem at full load/high rpm? I would love to diagnose this accurately without just throwing parts at the car.

 

Can anyone shed some insight on pulling the injectors? My workshop manual I have doesn't give me any information, It looks like there is a coolant hard line that will keep the rail/injectors from coming out, so i'm assuming drain coolant and remove coolant line? Do you generally remove the intake plenums or just work in a tight space? If anyone that has done the job before could shed some tips, that would be amazing, otherwise, i'll dive in and learn as I go.

 

Coupe

 

Great news Gentleman! Sent injectors to injectorexperts.com just north of me in Ohio and cleaning/balancing the injectors fixed my problem!

Thank you everyone for the advice.