Hellcat with Magnuson 2650 idle hangs after hard acceleration

Working on a Hellcat with a Magnuson 2650
Previously had a modified stock blower and drove around with a vacuum leak for about a year, (a few hundred miles, vehicle is rarely driven). So while it was apart the owner wanted to switch blowers.

Manual Trans
93 oct (100 oct after issues are sorted)
Magnuson 2650 with the smallest of the 3 available pulleys installed
Stock TB
Stock Intake
Stock Pumps
ID1000's
American Racing Longtube Headers

Just started tuning the new setup and have two issues:

1. The vehicle wants to run severely negative timing (-64 degrees) on cold start so I set the minimum timing in the spark section to -5 degrees on cold start to try and remedy this. Is there a better fix for this?

2. The idle hangs up around 3000rpm after any hard acceleration. I'm not sure what to modify to remedy this.

The cal file and a log are attached.

If anyone has any ideas or has ran into this before let me know!

Thanks!

Attachment 78523

Attachment 78524

Looks like the supercharger flow table is *very* high for the amount of boost being seen... stock peak kpa is what, 180kpa? 200kpa seen here, so the supercharger table maybe only needs to be increased by 15-20%-ish,

The bypass flow table isn't really going to be able to drive the bypass to open fully... you want that bypass all the way open when it needs to be... whats the bypass setup on the Magnuson? is it a stock hellcat bypass or is it something aftermarket?

Looking at the install sheet, it appears the stock bypass is used and it isn't shrouded or otherwise having anything that may interrupt its flow, so the bypass table shouldn't need to be changed at all....
http://www.magnusonsuperchargers.com...%202015-18.pdf

Thanks for the reply,
Yes, the stock bypass is re-used.
I'll make changes to the Supercharger airflow table, revert the bypass table to stock, and do some additional testing.

you will still have to change the supercharger airflow table... BUT, the % you change it is related to the absolute KPA increase, NOT the relative PSI increase.

Made progress on the RPM's hanging after acceleration. Drops slowly now and hangs to around 2k rpm, I'm going to try opening the bypass further.

Vehicle also has a 5" aftermarket intake now instead of the stock airbox.

Updated tune and log is attached.

Attachment 78702

Attachment 78703

I still need to figure out why it won't cold start without limiting the minimum idle spark to -5 degrees.

Also, does anybody have an idea what could cause this? The MAP reading is freaking out mid-pull (pink in the log), maybe a pinched wire or loose connection?
I need to add some fuel to WOT but the car pulls strong and smooth, I don't "feel" anything wrong in the problem area.

Attachment 78713

Log all of the MAP sensors to see if they match. I can't see anything like happening unless there is a bad electrical connection. IMO it's not possible for manifold pressure to actually change that quickly. If it did, you would feel it.

Also, I didn't see the -64 degrees of timing in the log?

I normally see that KOEO when you start scanning before you start the vehicle so I would think that's normal.

I would have to check, but is your injector data correct?

Quote:

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Originally Posted by Jay@HAP

Log all of the MAP sensors to see if they match. I can't see anything like happening unless there is a bad electrical connection. IMO it's not possible for manifold pressure to actually change that quickly. If it did, you would feel it.

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Good idea, I'll log the other sensors too. That's exactly what I was thinking it doesn't lose power and a 3 kpa reading would be an extremely powerful vacuum not even possible with a boost leak or deep deceleration.

Quote:

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Originally Posted by Jay@HAP

Also, I didn't see the -64 degrees of timing in the log?

I normally see that KOEO when you start scanning before you start the vehicle so I would think that's normal.

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I have not uploaded a log with the stock minimum timing otherwise it won't stay running. All of the calibration files and logs I have uploaded have minimum spark set to -5 degrees in idle regions so it will stay running.

Quote:

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Originally Posted by Jay@HAP

I would have to check, but is your injector data correct?

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I used ID's latest data and double checked everything, but of course I could still could have missed something.

ID states in their data sheet "If any table has more cells than noted here, duplicate the last values for the additional cells." So I had to do that in the Mass vs Pulse Width tables and the inverse but nothing else special.

ANNNND another thing, Has anyone ever had to change the PRatio Max on a NN tune above 15 psi?

The stock values are 2.08 which is around 15 psi assuming you are around sea level (inlet pressure ~14.7 psi)

Quote:

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Originally Posted by VodeAn

Also, does anybody have an idea what could cause this? The MAP reading is freaking out mid-pull (pink in the log), maybe a pinched wire or loose connection?
I need to add some fuel to WOT but the car pulls strong and smooth, I don't "feel" anything wrong in the problem area.

Attachment 78713

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Believe that is normal when sensed MAP is disabled, once you are above the sensed map rpm/kpa (not visible in most HP Tuner views) it will begin to sample real MAP versus sensed (calculated) MAP. The peaks are the actual, the low spots are the calculated. Try to log the non-SAE PID of MAP sensor and you should get a better, cleaner log.

Could also be baro testing too. Not 100% sure.

Thanks, I'll log some of the other PIDs. This is on hold for a week or so; one of the pullies started making more noise than the usual cog dive whine.

The hellcat gets wonky if you dont raise the testing windows/limits. Stock sensors are good for 225kpa?... so yeah raise limits. If not it will take the wheel and do what it wants. I resorted to Map SAE. Put a 2.4 on two cats one with a different os letter and it set a code and mine did not. Had to set a test window slightly higher on that cat versus the one that just didnt set the code.