thunderstruck507

iTrader: (18)

When I first got my car running it was doing the 6200 shifts I had asked to be programmed as long as the car saw enough throttle, but now it will not. I haven't changed anything, but it now shifts at 5800rpm on the 1-2 and about 6000 on the 2-3.

This is assuming my tach is reading accurate so I'm going to double check it tomorrow and see, but what else could be causing the early shifts? I do know for sure the tps is reading 100% now via checking it with a diagnostic scanner.

I'm not getting any codes, car seems a little sluggish compared to how it has been but I attributed it to crappy humid/warm weather.

Appreciate any ideas guys! Thanks!

Atver300

iTrader: (8)

Thats it the computer decides which table to shift off of by the tps. So at 100% tps it should be using the the wot speed table and the wot rpm table and both must be met for a shift to occur. did you change anything like tire size

BobDoLe

iTrader: (11)

you've got "part throttle" shift tables and "full throttle" shift tables.
there's also "hot" tables and "performance" (or tow/haul) tables.

the basic values in each set of tables are RPM and SPEED. both RPM and SPEED values have to be met to command the upshift... so you can set it to shift at a certain RPM, but it will wait for the mph to hit a set SPEED.
when you change your gears or put in an aftermarket torque converter, you'll find that you need to lower the mph or the shift will be commanded late.

then there's the "HOT" tables - a separate set of RPM and SPEED that are used then the transmission fluid temperature hits a certain temperature (which is pretty high - about 279F stock).

the "performance" tables can be adjusted, but you can't switch over to them without a switch (like trucks with a tow/haul button).
i wouldn't be surprised if tuners leave "performance" and "hot" tables stock when tuning a car.

thunderstruck507

iTrader: (18)

I didn't change anything on the car is what has me confused. I guess tomorrow I'll get someone to ride with me and watch the tach on the scanner and see if maybe my factory tach is just reading low or slow

BobDoLe

iTrader: (11)

if you confirmed 100% throttle on the scanner and its hotter, what does the pcm think the transmission fluid temp is (from the scanner)?

other than that, i hope its just your factory tach.

performabuilt

iTrader: (25)

The MAF sensor can affect the shift try cleaning it

jimmyblue

iTrader: (11)

Read the TPS voltage directly with a meter at WOT
(key on, engine off is good). If it goes over 4.75V
the PCM will short-shift the trans for safety.

thunderstruck507

iTrader: (18)

interesting, I have been getting a code for "MAF/MAP out of range"

I'll also check my tps voltage

thunderstruck507

iTrader: (18)

tps voltage was 4.45, actually hit 100% at 4.25 or so but you could push the pedal further for more

don't have any MAF cleaner yet and the roads are still icy so i can't try driving it or anything

performabuilt

iTrader: (25)

The information below may be help full to you even if you dont have the code but does speak of the tps and maf relationship.

Found this on another forum posted as a single thread

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.

thunderstruck507

iTrader: (18)

went for a drive yesterday and the tach is almost dead nuts accurate, computer hit 5775 and shifted

gonna try to find a place around here that sells MAF cleaner next, any other ideas in the mean time? like i said it used to shift where it was supposed to, just kinda stopped

thunderstruck507

iTrader: (18)

cleaned the MAF, car seems to run a bit better and idles better but didn't change my shifts back

I'm confused what else to look for

performabuilt

iTrader: (25)

You may have to spend some time looking at your tuning to figure out whats happening, It is a control issue.