My 2012 Auto has always backfired/afterfired after I got an aftermarket tune. (Have had 3 tunes AED 93Oct, BBR E85, Dyno Tune by Jeff Smith @ CTPerformance E85). It was even worse as I deleted the CATs and added the exhaust. I had added a Aeroforce gauge to watch my AFRs and noticed the 11.4 on decel reading but not being experienced I paid more attention to the 13.8-14.3 that it displayed when idling or on the gas in daily driving. (I understand you have to convert those numbers for E85 that I run, but its still an easy way to track it). Anyhow, the car backfired almost all the time when letting off the gas as the car began to slow.
On a side note, I also added a one piece drive shaft and began to have a hard shift with a loud clunk only on decel. I figuered it was the 2-1 shift however, I learned that it could be shifting down from any gear based on speed. Well i made a thread on the forums asking do you need a tune after the drive shaft install and got chastised pretty hard as if I was an idiot for asking. Well I went back and with the help of Kelly @ BMR via a phone call while under the car, set the pinion angle just right to ensure that wasn't the issue. It still clunked! Little did those people know that gave me such a hard time,that typically they would be right, however with the auto there CAN be an issue with tuning and heres why....
My tuner identified that the car was going real rich on decel so he set out to figure out why. He finally found, "in the coasting tables", that it was commanding a rich condition. (He could tell you the AFR/Lambada numbers it was commanding and I am sure the guys that tune know this) He went in and made the changes. The fact that so much fuel was being dumped as it coasted changed a lot of factors causing secondary and tertiary effects. One of these was the hard shift pressure causing the abrupt shift and clunk. He made the simple changes in the tune and now it drives like a dream. Backfire is completely gone, it has no clunk or hard shift and it feels so nice to drive it. I have seen several threads about the 2011-13 backfiring, or as some call it, after firing so I decided to make this thread just in case it helps someone out.
On a side note, I also added a one piece drive shaft and began to have a hard shift with a loud clunk only on decel. I figuered it was the 2-1 shift however, I learned that it could be shifting down from any gear based on speed. Well i made a thread on the forums asking do you need a tune after the drive shaft install and got chastised pretty hard as if I was an idiot for asking. Well I went back and with the help of Kelly @ BMR via a phone call while under the car, set the pinion angle just right to ensure that wasn't the issue. It still clunked! Little did those people know that gave me such a hard time,that typically they would be right, however with the auto there CAN be an issue with tuning and heres why....
My tuner identified that the car was going real rich on decel so he set out to figure out why. He finally found, "in the coasting tables", that it was commanding a rich condition. (He could tell you the AFR/Lambada numbers it was commanding and I am sure the guys that tune know this) He went in and made the changes. The fact that so much fuel was being dumped as it coasted changed a lot of factors causing secondary and tertiary effects. One of these was the hard shift pressure causing the abrupt shift and clunk. He made the simple changes in the tune and now it drives like a dream. Backfire is completely gone, it has no clunk or hard shift and it feels so nice to drive it. I have seen several threads about the 2011-13 backfiring, or as some call it, after firing so I decided to make this thread just in case it helps someone out.
