Harsh downshifts after cold air intake?

[SilverBullet6.0]

Hey guys, ive tuned the 6l80e in my 2010 silverado following the thuning school's guide and a few pointers i've picked up on here along the way. I was previously running just a modified intake tune with the factory airbox and maf location and had my trans shifting pretty good! This weekend, i swapped my intake setup for a k&n cai the relocates the maf closer to the tb in a straight section of the tube that is slightly smaller than the rest of the tube, which i assume k&n formed that way to simulate the factory maf environment. That night, i was driving and everything seemed normal until i kicked it down to pass some slower traffic. The 6-3 downshift was incredibly harsh. Like "spit a u-joint or rear end out" harsh. I've been playing with the tune alot today and cant seem to nailed this down. Any ideas? I didnt think the cai could cause this, but it was the only variable changed.

[abumalik]

Hi , did you manage to sort this issue. I am experiencing a similar symptoms to yours.

[SilverBullet6.0]

No I didnt. I eneded up just turning tm back on for downshifts.

[Spartus]

Same issue with mine. When I nail it to pass it feels like it's going to rip the rear end out of the truck. I've turned back on TM for downshifts and will re-load it tomorrow, hoping that helps. What are you guys running for line pressures? Mine are up to 160lbs. Upshifts feel nice and positive.

[abumalik]

Same issue with mine. When I nail it to pass it feels like it's going to rip the rear end out of the truck. I've turned back on TM for downshifts and will re-load it tomorrow, hoping that helps. What are you guys running for line pressures? Mine are up to 160lbs. Upshifts feel nice and positive.

Max line pressure set to 105 psi. Upshift on the soft side but thats OK for me. My TM is enabled , but still have the abrupt downshift issue.

[abumalik]

No I didnt. I eneded up just turning tm back on for downshifts.

My TM has always been on , did it help after you turned TM on in your case.

[VodeAn]

Can you post your tune file and a log of the event?

[abumalik]

Can you post your tune file and a log of the event?

please see http://www.hptuners.com/forum/showth...light=abumalik

Please see post 29 for the tune and 36 for the log file.

PS: I dont have any DTC errors any more , but still facing the same issues

thanks

[Longslyde]

By changing the tube, you changed the airflow to your MAF. The MAF is the primary component to calculate delivered torque to the transmission. This change in airflow, whether it is reading higher or lower......my guess is lower since downshift's are harsh, has changed your Delivered torque to the transmission. Been there. Lol! If you really feel like testing my theory out, put the stock airbox and tube back on and log your Delivered Torque. Put the aftermarket stuff back on and log again. I'll bet it changed a fair amount. You will need to re-scale the maf frequency table to cure this and get Delivered torque to read correctly. Keep in mind if it affected it far enough, you could damage the transmission because the tcm "thinks" you are lighter on the throttle than you actually are. My guess is that the upshift feel has changed slightly too? maybe softer shift or intermittent flare? Just a guess, but I'm sure that is the problem you are running into. Don't start changing you transmission tune too much until you get that fixed. It will drive you insane... I know! Good luck!

[Dr. Nopps]

Double check your IAT sensor, which is often R&R during an intake swap. If left unplugged, shorted, or damaged I have seen vehicles slam into gear at max pressure as a result.

[Longslyde]

Not taking away from the previous post, but I believe the IAT is built into the MAF on this particular setup, further making it all the more important that it is clean and reading correctly. The slightest change to the air tube will affect the flow across that sensor. I know this because when I added the supercharger to my config, the maf was off by a large amount and caused me a great deal of heartache because I overlooked the DT readings. Good luck!