LIMP MODE HELP, 911!

[WidowMakerTRX]

ah man, not having the stock tb to test with is a bummer, that would have been an easy 15-minute sanity check.

buying it from 797 performance is solid though—they are a very reputable vendor, so you definitely got a legit part. and frp (flyin' ryan) is a highly respected mopar tuner. ryan absolutely knows his way around these hellcats.

honestly, knowing ryan is your tuner makes me lean even harder into dino's point about the hardware being a dud out of the box. if a top-tier tuner is struggling to keep it out of limp mode during a basic 65mph cruise, it usually means the physical hardware is doing something the software simply can't control—like the blade literally getting ripped open by vacuum.

here is the million-dollar question for your 797 invoice: does it just say "nw108" or does it specifically say it's the "boosted" version?

nick williams literally had to release a specific "boosted" version of the 108 with a heavy-duty motor and stiffer internal spring because big blower setups were having this exact flutter issue. with your 2.90 upper, 10% lower, and that killer snout, you are spinning that supercharger incredibly hard at part-throttle. if 797 just sold you the standard nw108, your engine vacuum is completely outmuscling that little electric motor.

shoot that datalog over to ryan. give him the exact timestamp where the "actual" blade position spikes past 30% while his "commanded" throttle stays flat at 2.8%. ask him straight up: "ryan, the log caught the blade getting sucked open by vacuum while cruising. can you bump up the drive-by-wire motor current to fight the flutter, or are those tables already maxed out for this 108?"

he’ll know exactly what he’s looking at when he sees those two lines diverge. you've got the hard data now man! let ryan make the final call on the software side. if he says his tables are already maxed out, you know for a fact you need to get 797 on the phone to warranty out that hardware.

(and idaho, i used paragraphs again, sorry buddy. )

It doesn't say any of that. 797 only had one Nick Williams for the Hellcat on the site... see screenshot. Thats all the info i have.

 

[AZDinoPwr]

I do not have the stock anymore.

The Throttle Body is a brand new Nick Wiliams that i bought from 797 Performance. It says it is the NW108 for the hellcat platform.

My tuner is FRP Tuning...

I might still have my stock one sitting around. Will look when I get home.

I assume this is something that you and your tuner have already discussed at length? I know the 108s are supposed to be plug and play but I had to work through some TB tuning with Dusterhoff in order to get my launch dialed in (tip in at high rates was causing an issue).

 

[Digerati]

It doesn't say any of that. 797 only had one Nick Williams for the Hellcat on the site... see screenshot. Thats all the info i have.

1. What you currently have (Standard Motor):Nick Williams 108mm: https://797performance.com/products/nick-williams-108mm-throttle-body-15-21-hellcat(notice the standard description—nothing about upgraded motors)

2. The "Boosted" Alternatives (High-Torque Motors):Kong Performance 108mm: https://www.kongperformance.com/products/kong-108mm-hellcat-demon-trackhawk-redeye-throttle-body(look at the bullet point in their description: "High torque motor built to last on high boost combinations.")

OR

SDG Motorsports Upgraded 108mm: https://www.sdgmotorsports.com/product-page/williams-108mm-throttle-body-hellcat-demon(look at their description: "Upgraded electronics: Enhanced performance with no closing issues under high boost conditions.")

so, your physical hardware diagnosis remains exactly the same—your massive blower is simply outmuscling the standard electric motor inside that nw108. ironically, you bought your snout from sdg, but your tb from 797. if you had bought the tb from sdg, you probably would have gotten the one with their upgraded electronics!

send the log to ryan first. if he says he can't fix it by bumping up the drive-by-wire current in the tune, you will likely need to ditch the standard nick williams and swap over to the kong or sdg 108mm so you have a strong enough internal motor to physically hold the blade shut.

(idaho, i didn't even use capital letters this time. you're welcome. )

 

[WidowMakerTRX]

1. What you currently have (Standard Motor):Nick Williams 108mm: https://797performance.com/products/nick-williams-108mm-throttle-body-15-21-hellcat(notice the standard description—nothing about upgraded motors)

2. The "Boosted" Alternatives (High-Torque Motors):Kong Performance 108mm: https://www.kongperformance.com/products/kong-108mm-hellcat-demon-trackhawk-redeye-throttle-body(look at the bullet point in their description: "High torque motor built to last on high boost combinations.")

OR

SDG Motorsports Upgraded 108mm: https://www.sdgmotorsports.com/product-page/williams-108mm-throttle-body-hellcat-demon(look at their description: "Upgraded electronics: Enhanced performance with no closing issues under high boost conditions.")

so, your physical hardware diagnosis remains exactly the same—your massive blower is simply outmuscling the standard electric motor inside that nw108. ironically, you bought your snout from sdg, but your tb from 797. if you had bought the tb from sdg, you probably would have gotten the one with their upgraded electronics!

send the log to ryan first. if he says he can't fix it by bumping up the drive-by-wire current in the tune, you will likely need to ditch the standard nick williams and swap over to the kong or sdg 108mm so you have a strong enough internal motor to physically hold the blade shut.

(idaho, i didn't even use capital letters this time. you're welcome. )

Ok, youre starting to lose me...and not because i dont understand, but becausesome of this info is incorrect........the upgraded electronics on the SDG unit are to hold the blades OPEN in high boost situations, not keep them FROM opening....this is a scenario when at WOT and getting into higher boost pressure...not at low to no boost at cruising speeds when im not actually building any boost yet.

At idle and even at cruising speeds, I am not building boost....im still pulling slight vacuum or MAYBE at 1 psi boost...

 

[Digerati]

you know what man, you are 100% correct on that and i will gladly eat some crow there. you nailed exactly how they market those upgraded units for wot.

my logic was just based on the physics of a draw-through blower. a high-torque motor provides holding strength in both directions. at wot, it fights the massive air velocity trying to slam the blade shut. at cruise—especially since you are overspinning the absolute hell out of those rotors with a 2.90 upper/10% lower pulley combo—it provides the muscle to fight the massive vacuum trying to suck that giant 108mm sail open when it's clamped 97% closed.

but honestly, we're just splitting hairs over vendor marketing at this point, and you don't need my guesses anymore.

you already did the hardest part. you caught the ghost in the machine on a datalog. you have hard, undeniable proof of the "commanded" throttle sitting perfectly flat at 2.8% while the "actual" blade violently rips open past 30% without permission. that is the holy grail of diag. the physical metal blade moved without the computer telling it to.

since ryan (FRP) is your tuner, you are in the absolute best hands. he is a wizard with the hellcat platform. send him that log, point out the exact timestamp where the actual blade diverges from the commanded, and let him make the final call. he will know instantly if he can clamp that down in the software using the drive-by-wire electrical tables, or if your specific hardware is just a defective dud that needs to be warrantied by 797.

you found the smoking gun, you did the work, and you've got the right tuner to fix it. i'm going to step back and let you and ryan bring this beast across the finish line. keep us posted on what he says, i genuinely want to see this monster back on the road!

(and idaho, i kept it lowercase just for you. )

 

[AZDinoPwr]

Ok, youre starting to lose me...and not because i dont understand, but becausesome of this info is incorrect........the upgraded electronics on the SDG unit are to hold the blades OPEN in high boost situations, not keep them FROM opening....this is a scenario when at WOT and getting into higher boost pressure...not at low to no boost at cruising speeds when im not actually building any boost yet.

At idle and even at cruising speeds, I am not building boost....im still pulling slight vacuum or MAYBE at 1 psi boost...

Agreed. At your mdot air in those conditions it should not be an issue with mechanically overpowering the TB. Still possible to have a bad one out of the box where the gear lash isn’t on PAR. Or you damaged the gear set when doing WOT runs. What I think is more likely is that your airflow sensitivities across load on the motor are too tight. If you start to go outside of the table then it slams the TB shut to protect everything. So tuning would fix it.

Looks like I have my OEM one…just need to pull down a box after dinner. Send me a DM with your address and I can send it to you. You can use it to troubleshoot and then just send it back when done. I specifically kept my stock one because I know how picky these TBs can be.

 

[Digerati]

dino, boxing up your personal stock tb and shipping it across the country to a stranger is an absolute legend move. massive respect for that, that's exactly what makes car forums great.

and honestly, you completely nailed the endgame here. it brings this whole 4-month nightmare down to the final two possibilities: either the airflow sensitivity tables are too tight causing the pcm to slam it shut (which is what we were leaning towards back in post #3), or the physical gearset is just defective/damaged out of the box (like you just mentioned). your point about him possibly damaging the gears during his early wot pulls makes a ton of sense, and perfectly explains why the "actual" blade suddenly slipped open past 30% in his cruise log while the computer was trying to hold it steady at 2%.

@WidowMakerTRX definitely take him up on that offer. bolting that known-good oem unit on for a quick highway test is the ultimate lie detector. if the truck drives perfectly, you know the nw108 is mechanically junk and 797 needs to warranty it. if it still crashes, ryan knows exactly where to loosen up the airflow models in the tune.

you guys have a bulletproof plan now, and i'm officially tapping out to let you put this mystery to rest. definitely update the thread when you test the stock tb, i genuinely want to see this beast fixed!

(and idaho, no bullet points and still lowercase. peace out guys )