my tansmission has been shifting prematurely since i put my camshaft in its in over drive by 25 30 and shiftslike that at wot i cant launch car cause when i stab the gas it shifts into second immediately any help

 

PO121 or QUICK SHIFT 1-2-3-4 AT WOT after cam or throttle body install FIX
Found this on another forum posted as a single thread but wanted to have in this thread for easy reference also

PO121 CODE OR QUICK SHIFT 1-2-3-4 at WOT by 40 MPH FIX
Found this info on another forum and I know many people have popped up with this issue and wanted a fix. This would appear to be it. Hope it helps someone.

The curse of the P0121 Code... This code is infamous for giving people with larger cams fits...everything from traction control troubles, to shift point issues to just the good ole' P0121 code showing up for seemingly no reason making people scramble to purchase new Throttle Position sensors, adjust their set screws, etc, etc.

Before I go any further have a gander at the DTC information provided by LS2.com

http://www.ls2.com/boggs/dtcs/DTC%20P0121.htm

To outline a few key points

Quote:
The MAP is greater than 65 kPa

Quote:
The predicted throttle angle does not match the actual throttle angle

Quote:
All conditions present for 20 seconds

Now, that 65kpa map figure comes into play in nearly every LS1 Car/Truck because its the max map setting in most of the calibrations for the sanity test as shown here


Under normal circumbstances a stock cammed A4 will probably idle at around 35-40 map. When switching to a larger cam with more overlap your map readings could go up to as high as 70 or more kpa map which is way outside of the normal boundries. On a stock cammed car you'd probably need to be at around 30% tps to hit that same map number which is where that predicted throttle angle quote comes into play.

Now onto the last quote the 20 second timeframe. This will Usually come into play more often than not at idle with large cammed vehicles because many times your steady state map will be within the map sanity guidelines so there is a good possibity you might not see this code pop up immediatly.

There are a few ways you can cure this issue
a. Do as suggested in the help file which is to just set the min to 0 & max to 100
b. Adjust them to YOUR liking so you'll be within a reasonable limit. This will help determine if there IS a real issue with your TPS sensor later down the line.

So there you have it, as good an explanation I can come up with for that bastard code. So the next time you go WOT in your auto LS1 with a large cam & you go from 1st to 4th by 40mph or just a nagging p0121 code for no obvious reason you now have the info needed to fend it off.

 

its not a very large camshaft its just a ls hotcam would that still make a difference

 

and would a larger maf possibly hlp the problem or no

 

im hoping to have the maf faults reset as soon as i can accumulate money to do so thanks for the help