You have some sort of wiring issue going on, the throttle body lightning bolt confirms that as well. The switching you are seeing is the PCM switching between a default value when it sees a fault and actual readings. Have you gone back through all your wiring to the throttle body and your grounds?
I too thought it was wiring in the beginning, but the car runs and drives perfectly with the stock map sensor, with no throttle light, no CEL, and the scanner looks perfect. I can cruise it around while staying out of boost with the stock map sensor and everything is great, no cels, no throttle light, etc. As soon as i plug in the 2 bar sensor and change the map scaling the problems start. The car does have an arrington throttle body on it, which could possibly be an issue, but he has had it on there for months before he installed the supercharger with no issues. Ill put the stock throttle body back on to test, but i dont have very high hopes. I have also looked over the grounds and everything seems to be good, but is there something in particular i should be looking for? Mind you the car has 2000 miles on it, and the heads or block has never been out of the car, so there should be no reason the grounds on the heads or block are missing. I also checked continuity between the middle wire on the map sensor to the ground post on the passenger fender well and there was continuity.
Tried the stock throttle body, and no difference. It almost seems like there is a table that we cant see that isnt allowing the baro voltage to be as low as the 2 bar sensor is sending to the computer, and then its going into limp mode and throwing the p0129 code (baro pressure too low) and the computer is using a fixed/default value as the baro pressure, like 06300CSRT8 said above. It is just really odd to me that the Baro pressure has NEVER been correct with the 2 bar sensor values in the tune, no matter how much i change the offsets or slope... idk i give up for today...
Sorry and you have tried a different 2 bar?
I have seen it before, a 2 bar packaged and even LABELED from mopar with a 2 bar part number yet ended up being a 3 bar. Happened twice to me years back when wrenching on SRT4s. It would make your baro reading be extremely low if voltage output was closer to a 3bar.
Yes we have tried a brand new in box 2 bar sensor, as well as a working 3 bar that i robbed off a jeep here in the shop, and they all act the same way, KOEO MAP reads correctly, but Baro never reads correctly, always too high, and always the p0129 CEL
Have you ever done a full read and saved it AFTER you uploaded the MAP settings? I know you posted what you believe was sent to the PCM, but then doing a full read and observing the changes actually stuck would verify to some degree if the settings are sticking.
I just tried this, and did a full read, and the tune it read is exactly the same as what was written to the PCM...
So i learned something new last night, I got out our trinity and scanned the car with dataviewer, and i was able to find a PID for MAP voltage. For the first start up, when its in limp mode and has the code, etc, the MAP voltage does not change at all on the scanner, it stays at atmospheric voltage, 1.93v, the whole times its running, and then once you kill the car and immediately restart it, the MAP voltage will then read correctly and go down to about ~.65v at idle, and no more limp mode. What is weird, is I checked again the voltage that the MAP Sensor is outputing to the computer after the first start up, and it is actually outputting the correct voltage to the computer, but for some reason the computer is not reading it and its staying at 1.93v during that first start up.
Not gonna read thru all the comments but there is a key on baro min volt scalar that needs to be lowered. It is usally 2.2 volts on a 1 bar and needs to be rescaled.
The Baro Min Voltage stock on this car is .92 volts. I have lowered that all the way down to .10 volts, and have even tried 1 volt, with no success. I will add that his 2014 RT that this supercharger was on before did infact have a baro min voltage of 2.2 volts, and i changed that to 1 volt for that car and it worked perfectly.Originally Posted by Moparking
Do you have a Witech or access to one? If so, maybe flash a stock cal back in it, take a "stock" read with HPTuners and start again. Just change the values for the MAP sensor you are using.
You can also reflash it back to stock with the Witech and try tuning with "the other tuning software" and see if the problem occurs - just trying to eliminate variables and not suggesting using anything other than HPT to tune this in the long run.
Unfortunately we dont have Witech here, but thats a good idea. Ill have it flashed back with a stock cal and start fresh and see what happens.
I was able to try the "other tuning software" and wrote a quick tune using it with just the MAP scaling changed for the 2 bar, and the results were exactly the same as with HPT.
Another way to test it would be to put a stock 1 bar in, but leave it programmed for a two bar. If it runs good, you can then be sure your settings aren't taking.
any updates?
We are having the same exact issue with a 2016 SRT8 Cherokee that has a Procharger.
Have you come up with anything on this?
I have had 2 2016's do this same exact thing. One we did last November and the 2016 Grand Cherokee I have now. We took the kit off his 2015 and installed it on the 2016 He just bought. Now we have this same fault code issue. I thought I red something where these vehicle will not accept a 2.5 bar sensor. Maybe someone else has more wisdom about this. Every time at start up it will show up wrong baro at key ck.
From the dead.. Did anyone ever figure this out?
Again has anyone figured this out?
Anyone had any luck solving this issue ?
i have a similar case
I have this problem right now
Reply With Quote