Changes to tune with baro & iat breakout harness and 3 bar map

[DobermanRacing]

Hello and preemptively thank you for taking the time to help with this.

I have a 2015 Z51 M7 C7 with an A&A centri, tsp long tubes with an aem wideband added, on it.

I have a DSX baro iat breakout harness. I have their iat sensor and what I believe to be an LS9 3 bar map sensor also from them.

From all the reading I've done about installing these on here, Camaro6, and the corvette forums were on vehicles that went FI and have not been tuned yet.

My car is already tuned and I'm trying to figure out if the iat and baro breakout will affect the tune or can I just plug it in and go?

I know the map sensor will need to be rescaled but to confirm what rescaling does is changes the table the ecu uses for x volts equals x pressure but now x volts equals y pressure.

When the map sensor is rescaled the car shouldn't need to be retuned, correct?

[GHuggins]

In a perfect world it shouldn't need to be, but if it was "tuned" with the baro reading wrong then fueling will be affected as baro should no longer climb with wot and I have seen where switching from a ls9 map to a lt4 map made them idle differently so you won't know until you do it.

[DobermanRacing]

I've attached the current tune and 2 logs. "cold night.hpl" is a cold start and some driving with the 1 bar sensor. "3bar.hpl" is with the DSX iat/baro breakout and 3 bar installed. My wideband reads 1 point lean compared to the tuners wb so I've created a user math to correct this. I don't know if the math saves locally or will go with the logs.

[rabbs88]

Are you saying your car was tuned with a 1 bar map sensor and the A&A kit? Now you want to swap to a 3 bar?

[DobermanRacing]

Are you saying your car was tuned with a 1 bar map sensor and the A&A kit? Now you want to swap to a 3 bar?

Yes I want to run the 3 bar and the breakout harness for the baro and iat out of the maf.

[rabbs88]

With all due respect, find a new tuner. You can't tune for positive pressure with a 1 bar map. Literally imposible unless it was a MAF only deal which is lazy at best and obviously doesnt use the map sensor. You can install the new map and breakout harness but you will need to be properly tuned...yesterday

[GHuggins]

Yes, I guess that wasn't clarified enough to begin with or I didn't read enough into as a lot of my guys are swapping from ls9 maps to lt4's for temperature accuracy and I thought you were just asking about swapping to the breakout harness. You can't just go from a 1bar map to a 3bar and expect everything to be perfect. It'll need the VE dialed in along with other things as fueling calcs change even in theoretical 100% MAF mode with the VE changes. I don't know why all of these kits are keeping the original map sensors. They should come with the correct lt4's to begin with.

It's also very well possible that your tuners wideband is wrong. If you're using a good wideband it should be accurate without needing to skew it with a special math.

Now if you want, you can tune the VE in rather easily with the right math channels. Go towards the end of the gen 4's thread on what is dynamic airflow. It has all of them in it. Then lock you cam at 0 and dial in the base table. You can use Cringer's VE tool to dial in cam movement from there.

[GHuggins]

Just took a look at the tune. Looked all too familiar with another one on here... You should be able to use the math to dial in your VE whilst dialing in your MAF. Just make sure to set the cam to 0 and dial in the main table first then dial in for max cam position and then clean up after that.

[DobermanRacing]

It was tuned by a shop that is supposed to be one of the top tuners on the east coast for late model GMs and it was a maf only tune as far as I know 🫣

[GHuggins]

Yeah, hear that often too You can't be a top tuner and leave a 1bar map on a blown setup or not bother to dial in the VE, torque models and so on

[DobermanRacing]

I just saw your reply about the wideband. It's an aem xseries 30-0334.

Its just running the factory calibration. Would you suggest doing an open air cal?

I had considered swapping it for a Ballenger AFR500CAN with NTK calibration grade sensor.

I have the bung in the mid pipe about 8" behind but in a different plane than the B2S1 narrow band sensor. I've attached a pic.

Screenshot_20230828_005857_Photos.jpg

Also I am aware I wrapped the headers in the wrong direction.

[rabbs88]

Your current wideband is perfectly fine. Mines an 0300 and has been in for a long time without re-calibrating and is still very accurate but if you wanted to re-cal it won't hurt anything. Like GHuggins stated, if you want to try to tackle this yourself check out these threads. Cringer's formulas work very well to get things dialed in quickly and accurately. Obviously this won't be everything you'll need to fix but it will help tremendously for now

https://forum.hptuners.com/showthrea...ynamic-airflow

https://forum.hptuners.com/showthrea...-the-Same-Time

[GHuggins]

All you need to worry about is what I circled plus what's been pointed out above. These openings can create channels to allow raw air into the exhaust stream. It's best to move those wide band style clamps to cover these and go over the header just a little. They'll collapse down to seal off after that.

As for the wrap. You can paint it with the DEI high heat ceramic paint and that will help harden and keep it in place. Then put a couple more metal bands on if you can. You kinda made a parachute to catch air there but that's Ok...

A free air cal should have been done prior to installation, but yes if it wasn't done then remove the sensor and allow it to hang in open air powered on for a couple of hours. Come back and do a free air cal after that. Personally through my own testing I really like the AEM widebands. I didn't have a Barringer to compare at the time, but the AEM is right there with my very expensive Lambda Pro unit as far as picking up the transients instantly and everything like that. Plus the AEM is the only one I know of to be OBD2 CAN compatible for super easy install and setup. You should be able to just log SAE lambda and show the correct reading as long as it's calibrated correctly and going through the CAN...

[DobermanRacing]

Thank you both. Going to get the exhaust clamps corrected, do the open air cal, and then start working on it.