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Thread: 2016 Scat Pack 2 bar MAP scaling issues

  1. #1
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    2016 Scat Pack 2 bar MAP scaling issues

    I have a 2016 Challenger R/T Scat Pack Auto here that the customer installed an Edelbrock supercharger on, which he took off his previously owned 2014 R/T before he traded it in for the Scat Pack. I had previously tuned his 2014 R/T with the Edelbrock on it, and he brought the Scat Pack to have tuned as well after installing the Edelbrock on it. I am having issues getting the MAP/BARO Sensor to read correctly after imputing the slope and offset for 2 bar. The car immediately goes into limp mode when you start it (only has 3rd gear, throttle light blinks, check engine light, limited to ~2000rpm, runs terrible), and has a check engine light for p0129 - Baro pressure too low.

    What i am using for a 2 bar sensor:
    MAP Sensor Linear - 46.38
    MAP Sensor Offset - 4.8

    With this data, i can get the MAP to read correctly with key on engine off for our atmosphere (around 90KPA ; 12.8 - 13.0 PSI), but the Baro pressure does not read correctly. It reads 14.1-14.2 PSI key on engine off. I have tried playing with the slope, offset, minimum MAP and Baro voltages and such, but nothing seems to work correctly. If i lower my offset to get the baro sensor to read correctly (~90kpa), then my MAP sensor will read much lower than atmosphere (~85KPA). If i raise the offset back up to get the MAP to read correctly, then my Baro will be way high (~97-98KPA)

    I cant seem to get the baro and map to read the same with key on engine off.

    I even stole a 3 bar MAP sensor we have on a 2014 turbo jeep here at the shop and plugged that in and inputted the correct slope (61.85) and offset (6.8) for that sensor and it does the exact same thing, except the Baro will read even higher (~110 KPA), while the MAP is reading correctly (90KPA), which rules out bad MAP sensor in my opinion.

    The only way i can get the car to idle and run correctly with no check engine lights and baro and Map to read correctly is to put the stock sensor back on and put stock values into slope and offset.

    Is there something different about 2016 MAP sensor and/or data that i am unaware of? What am i doing wrong? These values are the exact same values that i used for the same Map sensor on his 2014 R/T and they worked perfectly. Anyone have any ideas or have had the same problem? I have attached my tune file, along with the stock tune file, and a quick key on engine off scan. As you can see i have every baro PID open that i could find lol.

    Thanks,
    Attached Files Attached Files
    Last edited by totalengine; 04-25-2016 at 06:27 PM.

  2. #2
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    Quote Originally Posted by totalengine View Post
    I have a 2016 Challenger R/T Scat Pack Auto here that the customer installed an Edelbrock supercharger on, which he took off his previously owned 2014 R/T before he traded it in for the Scat Pack. I had previously tuned his 2014 R/T with the Edelbrock on it, and he brought the Scat Pack to have tuned as well after installing the Edelbrock on it. I am having issues getting the MAP/BARO Sensor to read correctly after imputing the slope and offset for 2 bar. The car immediately goes into limp mode when you start it (only has 3rd gear, throttle light blinks, check engine light, limited to ~2000rpm, runs terrible), and has a check engine light for p0129 - Baro pressure too low.

    What i am using for a 2 bar sensor:
    MAP Sensor Linear - 46.38
    MAP Sensor Offset - 4.8

    With this data, i can get the MAP to read correctly with key on engine off for our atmosphere (around 90KPA ; 12.8 - 13.0 PSI), but the Baro pressure does not read correctly. It reads 14.1-14.2 PSI key on engine off. I have tried playing with the slope, offset, minimum MAP and Baro voltages and such, but nothing seems to work correctly. If i lower my offset to get the baro sensor to read correctly (~90kpa), then my MAP sensor will read much lower than atmosphere (~85KPA). If i raise the offset back up to get the MAP to read correctly, then my Baro will be way high (~97-98KPA)

    I cant seem to get the baro and map to read the same with key on engine off.

    I even stole a 3 bar MAP sensor we have on a 2014 turbo jeep here at the shop and plugged that in and inputted the correct slope (61.85) and offset (6.8) for that sensor and it does the exact same thing, except the Baro will read even higher (~110 KPA), while the MAP is reading correctly (90KPA), which rules out bad MAP sensor in my opinion.

    The only way i can get the car to idle and run correctly with no check engine lights and baro and Map to read correctly is to put the stock sensor back on and put stock values into slope and offset.

    Is there something different about 2016 MAP sensor and/or data that i am unaware of? What am i doing wrong? These values are the exact same values that i used for the same Map sensor on his 2014 R/T and they worked perfectly. Anyone have any ideas or have had the same problem? I have attached my tune file, along with the stock tune file, and a quick key on engine off scan. As you can see i have every baro PID open that i could find lol.

    Thanks,
    Sounds to me like it could very well have 2 sensors, one of them a standard MAP sensor (which you are already very familiar with) as well as possibly a TIP sensor (Throttle Inlet Pressure). The much older Dodge Neon SRT-4 used 2 sensors like this, and in order to run a 3 bar MAP sensor, you would have to replace both the MAP and the TIP as they both rely on the same calibration settings for kpa/volt, and offset.

  3. #3
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    That very well could be the issue, as i had that same thought the other day. But to my knowledge, a 6.4 only has one sensor... but i could be wrong, maybe the new ones (15+) have two sensors like a hellcat? Does anyone have any info on that? I did take a pretty good look at everything, and there is definitely not a second sensor that i can see from up top. Im having the customer bring by his intake manifold and everything that he took off so we can take a look and see if something is different on it, maybe two sensors?

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    What happens when you leave Baro Learning on? I would also log your MAP voltage, post it up.

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    Leaving Baro Learn on doesnt change anything, still acts and reads the exact same. And i looked for MAP voltage and i couldnt find it. BUT, i just had a really weird thing happen just now, i turned on Baro learning, wrote the tune, it was the same, so i then turned it back off, and wrote the tune again, and it started up and ran perfectly, along with the map sensor reading perfectly at idle(baro was still at 14.1 though, which is wrong). I turned the car off, and then started it right back up, and then it went right back into limp mode, with the MAP not reading correctly at idle (reads 12.8psi at idle), and baro still wrong..... so idk what the heck is going on here. Here is a log of the idle with the 2 bar sensor installed and the two bar tune that i posted above.
    Attached Files Attached Files

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    OK look at this log, i was able to log whats happening now. This is a new development as of today. In the log you will see me start the engine, and the MAP KPA stay at 88kpa while its idling (not correct) and the car is in limp mode, and then i kill the car without stopping the log, and then restart it immediately back up, and bam, all of a sudden the MAP sensor starts reading correctly at idle and the car is no longer in limp mode. I was able to repeat this numerous times by letting the car sit a few minutes before restarting again, and the first time it would always start up and the MAP read wrong at idle (88kpa), and then kill it and immediately restart it and it will read correctly. Now what has always stayed the same is the BARO pressure reading wrong, it always reads 14.1 psi, (should be 12.8-13.0 at my elevation). Also, even after resetting the check engine light numerous times, it always stays on with a p0129 low baro pressure code.
    Attached Files Attached Files

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    Your Map isn't seeing anything in the intake manifold, it's only seeing atmosphere. How is it installed?

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    Its installed directly into the back of Edelbrock. It was installed in the same place when it was installed on his old car. It is seeing manifold vacuum, because it if wasnt then it wouldnt read vacuum after the 2nd start up. If you watch the latest log i posted, after i kill the car and then immediately restart it, it will then start reading vacuum.

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    Was rewiring the sensor pigtail required, or was it a direct fit for the sensor? And even if it was a direct fit, did you verify the pin-out information on it?

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    The kit came with an extension harness to reach to the location where the sensor pops into the supercharger, and it is a direct fit. Tomorrow i plan to try to rig something up to where i can eliminate the extension harness all together and plug the sensor directly into the factory harness plug and run a hose to the supercharger to get vacuum. I have seen extension harnesses be bad, but at the same time, i really dont think its bad because the factory map sensor works perfectly when plugged into the extension harness, but ill try it anyways and see what happens. When i robbed the 3 bar off the 14 SRT Jeep to try it on this car, i checked the factory harness on the jeep to find out what each of the 3 wires did, and compared that to this challenger, and the wiring was exactly the same. I dont remember what each was now, but i do remember the middle wire was ground. We also checked the extension harness, and each wire has continuity from end to end, and none of them were crossed in the harness.

  11. #11
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    Definitely still sounds like a mechanical / electrical problem versus a tune issue though. Fact that it will read baro pressure at idle when it should be reading vacuum tells you the signal it is reporting isn't right. Double check all your grounds too around the back of the motor.

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    Well, i eliminated the extension harness and plugged the map sensor directly into the stock harness plug, and ran a hose from the sensor to the supercharger to get a reading. It didnt change a dang thing, still exactly the same. First start up the map will read 90 kpa while idling, then by killing the car and immediately restarting, the map will magically start reading correctly. The customer brought me a brand new 2 bar sensor just to try, and it didnt change anything at all.... After a day full of testing, I have come to the conclusion that it has to be something tune/software related. In my opinion, the map sensor is outputting the correct voltage to the computer at all times, whether it be key on engine off, idling, or just light throttle, but the computer is not interpreting the voltage correctly it seems. After testing the stock 1 bar map sensor, and seeing exactly what voltage it outputs to the computer in numerous situations, im pretty positive the 2 bar is outputting the correct voltage as well... basically its outputting approximately half of the voltage in the same situations as the stock sensor, which to me, makes perfect sense, seeing it has approximately twice the pressure range as stock. For example: Stock sensor with key on engine off - sensor outputs ~3.96v With the the two bar sensor, it outputs ~1.94v key on engine off. This makes sense to me, but i could be wrong. With all the research ive been doing, my slope and offset for the sensor in the tune is what everyone says to be correct for a 2 bar, and ive used those same values numerous times with other FI cars with 2 bar sensors. And when reading the MAP with key on engine off, it reads the correct KPA, unlike the Baro, which does not read correct, and never has with the 2 bar sensor, no matter how much i play with the offsets. Any input from anyone?

  13. #13
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    That's about right for voltages here's the mopar graphs of 1 vs 2 bar

    http://bertok.us/pics/MAPGraph.jpg

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    The problem seems to be once it's running its not reporting the correct voltages, what are the voltages once it's running? It'll spit a low Baro Error when key on Baro plus current map is below the threshold and it seems like it's reading higher voltage once the car is on. I'll check your tune again, driving right now, what do you have have as your voltage min, slope, and offset?

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    Just as a clarification about the SRT-4 sensor, it is actually a 2.25 bar sensor. Not that this adds anything relevant to your issue. Your slope and offset values are correct for that sensor.

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    It seems to be reporting the correct voltages when its running also, just from memory from yesterday, with the 1 bar sensor, at idle, its around ~1.4 volts and it reads around ~30kpa on the scanner. With the two bar sensor, at idle, it reads about ~.68 Volts, and scanner reads about 30 KPA. On the first start up with the two bar, when the scanner does not read the correct KPA at idle, the sensor is outputting the .68 volts. Upon killing the car and immediately restarting it, the scanner starts to read kpa correctly at idle, and the sensor is still outputting the same .68v. So the sensor seems to always be outputting the correct voltages, with no funny voltage readings or oddities.

  17. #17
    check that you don't have any codes setting because the MAP and/or BARO might be defaulting to a fixed value, then reading the true value after you key on/off again.
    I count sheep in hex...

  18. #18
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    Shouldn't baro voltage min be lower

  19. #19
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    I believe that if it reads lower than value it will used a calculated value

  20. #20
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    I do have a p0129 code, baro pressure too low, that i cannot clear before the first start up. After i start it up, kill it, then restart, it will then allow me to clear the code. But if i let the car sit for more than like 10 seconds after killing it, it will throw the code again. I also just tried setting the baro volt min to .10 volts, and that didnt change anything.

    Ok, so take a look at this log, ive found some funny stuff happening here. This log shows KOEO, start up, turning off, immediately KOEO, restart, and then killing it with KOEO for a few seconds.

    I have 3 Manifold Pressure Channels open and 3 Baro Pressure Channels open, Watch those six channels. Remember, our baro pressure is approximately 90KPA or 13PSI at this altitude.

    As you will notice, at first with KOEO, none of the baro pressures are accurate, and oddly they dont all read the same pressure. The middle Baro channel reads slightly lower than the other two.
    The top two manifold air pressure channels are correct for this altitude, while the third manifold air pressure is not correct.

    Upon starting, the top manifold air pressure channel does not change at all, while the second and third manifold air pressure will read, but read slightly differently, but they are pretty close to what they should be reading. Also notice the MAP in the charts does not read correct for idle. It reads about 60 kPA, should be around 30 KPA. Also, the throttle light is blinking on the dash and car in limp mode with a p0129 code.


    I then kill the car, and immediately restart it. Now, notice how the middle barometric pressure channel "jumps" to 14.1, and magically, all three manifold air pressure channels start to read, and read correctly. Also the MAP in the charts read correctly at this time. No throttle light, and not in limp mode anymore.

    Then i kill the car, and go KOEO for a few seconds. Watch the middle baro pressure channel, and also the bottom manifold air pressure channel. The middle baro channel will "jump" back to the 13.8PSI it was at in the beginning, and also the bottom manifold air pressure channel will "jump" from the correct value of 13.0 to 14.2psi.

    Does this make any sense to anyone? I noticed this and thought it was very strange.

    I will also add that during this whole scan, the MAP sensor voltage that is being sent to the computer is the same for each start up, and does not do anything weird to match what the scanner is reading.

    Ive attached the latest tune on the car, this one is with the map min volt at .10v just to try and see what happened.

    koeo, start, kill, restart, kill.hplTES Tune 1.hpt