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Discussion Starter #1
This question is for any of the guys out there running boost who have converted from the factory 1 bar Map sensor over to an SRT4 2.25 bar map or the SRT4 3 bar map sensor. I’ve found the offset information for the Map that I have to run for my boosted application (3 bar map). My question is, has anyone modified the stock 5.7/6.4 kpi fields on a GPEC2 PCM to read high then 100kpa for accurate boost reading? I’ve read that the stock PCM (GPEC2)can only recognize up to 15 psi of boost. I want to have my pcm see more than that amount of boost. If possible. I’d like to use Hellcat or Demon settings.


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Have you tried reaching out the the HP community? One guy I can think of that might be able to help is 06300CSRT8. Or Hemituna (Bill...Ben?) and/or Tbrtuning (Travis)
 

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The one thing I can say that I know about it - the scaling numbers along the side are mostly there for you - the tuner. The PCM doesn't do many things differently when you change those numbers - except hit the limit.

Whether it says 100kp or 50kpa, it's going to do whatever is on that line of the table based on map sensor voltage.
 

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The one thing I can say that I know about it - the scaling numbers along the side are mostly there for you - the tuner. The PCM doesn't do many things differently when you change those numbers - except hit the limit.

Whether it says 100kp or 50kpa, it's going to do whatever is on that line of the table based on map sensor voltage.
I have the same understanding, I was actually looking at that yesterday, it costs ~$170 to open the ability to rescale the tables.
 

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The only other issue is related to barometer compensation. And that depends on a lot of things.
 

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Discussion Starter #6
So I have found the information in the HPTuner forums and in the SRTforums. The map sensor I have for reference is

Min Volt .12v
Max Volt 4.80v
Map Lin - 61.85
Map Off - 6.8
Zero Volt - 1.61v

These are the setting for a Mopar 3 bar Map found in 08-10 Calibers. That said I would think that changing the information and the scales is necessary for accurate boost determination. Am I looking at this incorrectly?


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Discussion Starter #7
I have the same understanding, I was actually looking at that yesterday, it costs ~$170 to open the ability to rescale the tables.
MCCloud did you find this information out from HPT? Very interesting that changing the scale doesn’t change things I figured it’s like the injectors. Good data is best. Thanks fellas I’m digging way deeper into the tuning of these Hemi’s with boost now.


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MCCloud did you find this information out from HPT? Very interesting that changing the scale doesn’t change things I figured it’s like the injectors. Good data is best. Thanks fellas I’m digging way deeper into the tuning of these Hemi’s with boost now.


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First pass I looked through here, I was thinking of the scaling based on the device.
 

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It doesn't cost extra to change the column and row axis labels. I do believe there are a few that cannot be changed or that cannot be changed beyond a certain parameter.

To change the axis just right click on the table and go through the pop-up menus.

Choose COLUMN AXIS (top to bottom) or ROW AXIS (left to right) and then choose EDIT.
 

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DakBuilder,

Take a look at the file posted by Hemituna in this thread for an example of map sensor scaling.

 

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Back to what I was saying about the voltage.

In the "olden days" before all of the easy flash tuning and off-the-shelf tuning packages, we used to kludge a lot of stuff.

One method (although flawed for obvious reasons relating to the spark timing map) was to take a vehicle that was equipped with a 1 bar map sensor and exchange it for a 2 bar map sensor and then roughly double the injector size. Then dial it in with something like an Apexi Super AFC that is simply a device that offsets the 5v signal from the load sensor (map or maf) based on an rpm vs tps scale. It worked pretty solidly for fueling, but often resulted in excessive ignition timing at the onset of boost.
 

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DakBuilder,

Take a look at the file posted by Hemituna in this thread for an example of map sensor scaling.

That tune in there is the one I grabbed the air tables from...the throttle response is soooo nice. Also there is almost no lag between commanded and actual FA. Before I used to see knock because boost would kick and took a while for commanded FA to show up...even at 2V WOT threshold. For some reason on my PCM if I tried to bump up FA enrichment rate the injectors would freak-out and car would run pig rich....now back to scaling.
 

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That tune in there is the one I grabbed the air tables from...the throttle response is soooo nice. Also there is almost no lag between commanded and actual FA. Before I used to see knock because boost would kick and took a while for commanded FA to show up...even at 2V WOT threshold. For some reason on my PCM if I tried to bump up FA enrichment rate the injectors would freak-out and car would run pig rich....now back to scaling.
Did you ever try making table 44450 0 instead of 512?
And table 44453 change to just .0006?
 

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Changing 44453 (FA incr) to 0.0006 (although it is currently at 0.0009 on my current tune which I plan to bump back down) is not enough and most tunes have it as much as 0.0100 which does not work for me and will cause the PCM to flag "injectors shorted" DTCs.

Changing 44450 (RPM max) to 512 instead of 8160 does nothing as well.
 

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That tune in there is the one I grabbed the air tables from...the throttle response is soooo nice. Also there is almost no lag between commanded and actual FA. Before I used to see knock because boost would kick and took a while for commanded FA to show up...even at 2V WOT threshold. For some reason on my PCM if I tried to bump up FA enrichment rate the injectors would freak-out and car would run pig rich....now back to scaling.
I tried these adjustments and end up with idle issues.. It hunts, I decided not to drive it like that, doing more research. I'm trying my Percent Request theory today to see how that affects throttle response, if it works like I think I will blend the 3 tables.

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I tried these adjustments and end up with idle issues.. It hunts, I decided not to drive it like that, doing more research. I'm trying my Percent Request theory today to see how that affects throttle response, if it works like I think I will blend the 3 tables.

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Yeah I had to bump up the values at <1V but did not touch the rest. BTW if you plot stock values of all 3 tables you will see they fall on top of each other. I noticed if I adjust small and large pedal too much from the ETC table things get funky in terms of drivability.
 

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Good know thanks, I'll take a look at that...

Hopefully this is helping DakBuilder... I've kind of hijacked his thread...

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Discussion Starter #19
DakBuilder,

Take a look at the file posted by Hemituna in this thread for an example of map sensor scaling.

Will do Spoolboy I’ve been living on HPTuners forums lately


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Yeah I had to bump up the values at <1V but did not touch the rest. BTW if you plot stock values of all 3 tables you will see they fall on top of each other. I noticed if I adjust small and large pedal too much from the ETC table things get funky in terms of drivability.
So did you synch up the numbers with all three tables when you made the changes?
 
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