[QUOTE=96capricemgr]Vacuum as in MAP sensor reading is how the pcm knows what kind of load is on the engine, less vacuum as in closer to atmospheric pressure, it knows there is more load and therefore needs more tranny line pressure.[/QUOT
I understand how to determine vacuum. I've thought part throttle shift points were determined by TPS position and MPH. Enlighten me.

 

That's correct. Both part throttle and WOT shift points are determined that way.

You should definitely need to have the values adjusted in an A4 with the 58mm TB if you don't want to break the tranny.

 

what do you mean adjust the valves? you talking bout the rocker arms and stuff?? i wouldn;t think so, but i know nothing bout auto trannies if they have valves in them. i'm installing a transgo shift kit next spring.

 

Trying not to step on any bodies toes, but WOT shift points are determined by programming.

 

What mods?

 

[QUOTE=anaik]There is the problem you are hung up on shift points and we are talking about hydraulic line pressure in the tranny which has to do with shift firmness and clutch holding power. You are correct shift points are scaled off of TPS/MPG/RPM.

 

Dwayne,

I am not hung up on shift points. They remained the same with both TB's, although softer with the 52mm. To give an example, With the 48, driving normal, my 1-2 shift would chirp the tires with the TransGo kit, not so with the 52.
I do feel the engineering to determine when to shift is flawed for a hipo car. To give another example, I installed 4.10's and took it to the track with street tires. It spun so hard the VSS determined the car was ready for the 1-2 shift. When it did, the spinning stopped, then the PCM determined I was going to slow to be in 2nd, so it downshifted to first. What an experience that was, I went sideways. This was explained to me by Ed Wright. I had his tuneing at the time. He told me to get slicks.
I think the speed sensor should be on the front wheel.

 

The spin made the tires go the shift MPH so it shifted. The only vehicle I ever saw with the speedo driven at a wheel much less a non-driven wheel was my brothers old '72 VW conversion van complete with popup top and kitchen sink. Neutral was also at a slant not straight right to left.

 

You brought back memories. I had a '69 VW beetle that had the speed sensor on the front wheel.

 

That's right, but they use the same programming as part throttle shift points. In the shift table, there are different shift values (in MPH) for different TPS % values. The entry for TPS % at 100 gives you the WOT shifts.

 

Lol, I said "values" not "valves." I'm talking about the shift point values in the PCM. The shift points are based on TPS % which represent a different amount of air/power with a 58mm TB vs. the stocker.

 

my tuner emailed me and he said put the 58mm TB on and see how it idles and then drive it and see how it acts. he said that i shouldn't have to worry bout the tranny shift points. he seems to think it will be fine. i have a transgo kit so it will correct whatever the TB changes. correct?