Hey guys I got a level 2 performabuilt a little bit ago and was all pumped to get to run at the track and run a good time. Well first time down I leave it in D and it goes threw the gears stupid quick, and I end up running like a 15 sec quarter mile. Then I tried shifting and every time I try shifting at 6k rpm where my tuner set it at it bounces off the limiter and has me run a slower time. I do not understand it, and really starting to get frustrated with it

 

The quick shifting and the other syptoms are ussually related to a MAF/TPS relationship issue. Sometimes but not always a code po121 may be present but it does not have to be. The trans is totally dependent on what the PCM commands it has no mind of its own and must either shift or slip when comanded there is nothing in between. However note the quck shifting at WOT can cause a premature failure. Its a fact that just because you comand a certain speed and RPM shift does not mean thats when it will actually be comanded tehre are many other variables. I will post a link below for one of those possibilites.

 

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.
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only thing is the tps sensor was turned off and we tuned it like that

 

I may be wrong but I dont think you can tune without TPS I mean how else would the PCM know your throttle position which is critical to determine shift points and line presure.

 

Well I went to the track with it on and it did the same thing, also at WOT now it will not go into od

 

In a Speed Density tune the MAF sensor will be deleted. Meaning, the PCM is programmed to only look at TPS and MAP for determining engine load. It is considered a basic tune typically reserved for rowdy street machines or racing engines equipped with EFI systems.

g

 

I do not have a speed density tune

 

This cant be right. If it is, time to get a new tuner. Without tps nothing will work correctly especially the trans. Unless its a manual VB.

 

No mvb. The car pulled timing on the dyno so we turned the sensor off. But when I did my run at the drag strip it was on so I'm my sure

 

Well As I said the trans cannot shift or not shift on its own but the TPS must be present I would say both when driving and tuning for the trans, The only cause of the early shift Im aware of is the post I put above.

 

This is one weird thread

 

Yeah... not much reliable info from the OP that we can use to help him solve his issue! LOL.... we're only as good as the information we're given right?

g

 

Yes I am doing my best to help with very limited information

 

I do apologize, I am trying to do my best as well. But working 40 hrs a week going to school, and go reserve bs that I have to deal with. So let me start all over..

Got the car tuned originally everything was fine. Took it to the track and left it in D one time and it did the quick shift. Other wise I would shift it myself and it would either shift too early or hold the revs to red line. So we looked at the tune and everything look fine.

The other night I was racing a Corvette and the car wouldnt go into OD. Just hit the limiter at 3rd. Well the car sat for two days and then drove it to school, and the car runs like complete crap. We hook it up to hp tuners and the MAF is not putting out anything. Swap MAF's and still nothing. So I am not sure if this incident granted it was happened afterwards caused some affect on it. But hopefully sometime this week I can drop off the car and get some questions answered