6.1 with magnuson and hellcat TB opening tps too fast

Hi,

I'm sorry for the long message but I was wondering if you guys could help me with a question

I'm trying to tune a 6.1 hemi with a magnuson on 14 psi and hellcat throttle body. I've tried everything I can't think of with the pedal power tables, desired throttle along with throttle body airflow and I can't seem to keep the tps percent from jumping up from 22% to 35% rapidly. The throttle ramps in smoothly up till 22% but after that it opens quickly. It also causes map to jump from 60 kpa to low boost without moving the pedal much at all, like fractions of a volt. It seems even if i slowly press on the pedal it hits a point where it just wants to open the throttle. I've asked others tuners about this issue and they have said they have experience the same issue with no solutions.

I reviewed the last 6.1 I did but with stock throttle body and it had a similar issue but that car was procharged and on lower boost so it wasn't as noticeable. It also waited till 90kpa and 29% throttle before it happened.

I'm wondering if this is just inherent to these cars or if I'm missing something. I was hoping for some advice or just wondering if anyone has experienced this issue before and if they were able to solve it.

Please help

No, it is not an inherent problem and you can get them to be as smooth as glass.
Post up your tune and a log and see if we can't help find the issue..

Dude I tried what you posted from before about how it works. It's already improving. I think I'll be able to get it tomorrow. Problem was the previous tuner used a stock hellcat tb airflow table which jacked airflow model. Also looking at tps % vs airflow on the desired airflow table I saw huge jumps in desired tps vs airflow. So I raised the airflow axis in the .6-1.0 volts area, effectively making it want less tps for given airflow. End result, I see how it works now. I CANT THANK YOU ENOUGH!!!!!!!!

Also look at the flywheel power table.
It takes your pedal/desired throttle % and relates it to torque at flywheel vs rpm.
An NA is gutless at 1500rpm so 40% pedal gets about 70-80%TB opening to make it respond nice.
With a blower, this makes it very abrupt.
So reduce the low rpm area and then add some as rpms rise to keep the blower fed.
So basically a flatter table. This table can be very helpful in smoothing the power response vs rpm.
The DS guys never use this table because in DS it doesn't work....
That is one part of the reason they say you cannot sort em out....

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Originally Posted by Hemituna

Also look at the flywheel power table.
It takes your pedal/desired throttle % and relates it to torque at flywheel vs rpm.
An NA is gutless at 1500rpm so 40% pedal gets about 70-80%TB opening to make it respond nice.
With a blower, this makes it very abrupt.
So reduce the low rpm area and then add some as rpms rise to keep the blower fed.
So basically a flatter table. This table can be very helpful in smoothing the power response vs rpm.
The DS guys never use this table because in DS it doesn't work....
That is one part of the reason they say you cannot sort em out....

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That's new, Where is the Flywheel power table?

Engine/Airflow/Electronic throttle/Power % Request(flywheel)

The system works like this.
1. Pedal % request table. Pedal voltage vs NVRatio requests a power %
2. Power % request flywheel. Takes the power % request number and applies it to RPM.

So say you are in gear 1, NVRatio is 255 and pedal is at 1.50v
Power % request table is say.....40% as an example.
Take that 40% over to the flywheel table and you will see at different rpm this table requests different % to the power table.
This allows us to tailor the engine response and Tq thru the rpm range
So you can hold it on the dyno at 1.5v Pedal and slowly ramp it thru rpm.
You can use the flywheel table to smooth the TQ curve.
More power % down low and less up top or vise versa if it has a blower etc.

You can get them to hold a tq number from 1.5k - 6.5k if you mess around enough.
So if you hold the pedal at 1.5v 40% pwr request it can make say 300lb tq from 1.5 - 6.5k.
Go to 2v and 60% and it can do 400lb from 1.5 - 6.5k.
2.5v 75% and 500lb etc etc.

Then you can also use the Pedal % request vs NVRatio to get the right pedal/power response per gear.
So as to calm powerful cars down in the lower gears but be responsive to pedal in top gear.
Using NVR, you can feed in more power % request as it works up thru gears to allow for loss of tq multiplication.

Nice system really once you get your head around it. :)

I'm noticing where theres a jump in tps it goes from 1.0 tps volts up to 1.2 sharply but whats most interesting is at that point airflow drops to zero, then creeps back up. Whats the deal with that?

Its funny because i don't see any other dips in load, torque, ve or fuel mass so i don't understand where its calculation comes from

I'll post my tune and a scan when i get the fuel and timing dialed in.

Attachment 68807

current tune, not fully dialed in yet so be nice.

Attachment 68808

i realize the desired throttle table doesn't match the throttle body airflow table but it doesn't seem to make a difference other than making the numbers line up. what are your thoughts on the jump in throttle and airflow drop? i'll post a better tune file and scan tomorrow with a ramped in throttle scan. We're also installing a restrictor in blower bypass valve for a slower response on the blower which should help a little but i realize it's only a mask for an underlying issue. Let me know please.

Couple of things to try.
Move the FA WOT Threshold up from .8v to 2 - 2.5v
Smooth the Pedal request table as it jumps up quickly and maybe add some more TB airflow below .9v.
Hellcat TB is large so it needs to be opened nice and smooth.
On a blower tune you want to use more of the pedal range.
You are probably getting boost with very little pedal and this just makes things awkward.
You dont want much boost till 1.25 - 1.5v usually.
Then PE follows at around 2-2.5v when you have a little boost and WOT will be at 3.5-3.6v
Try and make it more linear and also the trans will appreciate the longer pedal.

Ok I'm trying a coupe thing tomorrow. I will post a new tune and log tomorrow night.

Fixed the problem, I adjusted the voltage of desired tps vs airflow table. Its a pita and definitely has a learning curve but once figured out its not that hard. I just had to play with all the tables one by one to really understand what they would affect. We really need a better way to log airflow.

Quote:

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Originally Posted by GPGTP

Fixed the problem, I adjusted the voltage of desired tps vs airflow table. Its a pita and definitely has a learning curve but once figured out its not that hard. I just had to play with all the tables one by one to really understand what they would affect. We really need a better way to log airflow.

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can you share how the best way you found to log airflow?

Quote:

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Originally Posted by boostlife

can you share how the best way you found to log airflow?

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there really isn't but total airflow and engine torque should get you were you need to be