I'm thinking that it's a possibilty of something for the computer to learn. I can't try it from here since the trucks I'm working on with this issue are far from me. Turn the key on and have someone put the pedal to the floor to 100% commanded tps. Have them hold the throttle there and have a second person manually open the throttle blade the rest of the way to 100% and hold it there for 30 seconds or so. I'm thinking the pcm may see this and learn the wide open tps range for the throttle body. This is just a thought though and I'm not sure if it will help or not.

 

There was an article about this not fully open TB thing in GM Hightech Performance magazine.
I think it was about a year ago. I can't remember if it was a cable or FBW that they were talking about.
What I do remember is that the TB could not physically open all the way because of a hard stop being in the way. They actually had to grind/file off a little material from that stop to get 100% open out of the TB.
I'll dig through the stack of magazines I have and try to find the article.
You may want to check this out too.
Remember this was on a stock LS1 TB.

 

i doubt thats it, but thanks for checking anyway!

if there were a "hard stop" in there, you wouldn't be able to open the blade further with your hand, which you can do.

 

Zippy,...I tried what you said and no dice. Can everyone check with a volt meter on the ACTUAL voltage they are seeing at the TB when at WOT? I am getting a non-linear curve at various blade positions. Its almost like an an asymptotic relationship or some kind of log reduction curve. Is that correct?

I didn't get a chance yet but I am using the wire harness from Speartech and I just want to doublecheck that the wires are not crossed anywhere. It could happen I guess but not likely. My bet is still with the TAC.

I have an adjustable voltage regulator on the shelf in the garage and will add a little voltage to the TB motor to see if I can get it to react to full WOT 90*. If it doesn't go to 90* I will venture to say it has to do with the TB internals.

BIGTEX used the SSR 90TB. Richard, are you experiencing any of the aforementioned issues?

 

I have tried that too. Just threw some TB performance codes.

This might help:

On ‘02 and LS2 TBs the dual TP sensors move in opposite directions while on the 03-05 TBs both sensors move in the same direction. So that explains the need to switch to the ‘02 TAC. Any comparisons should be made using a stock ’02 setup(TAC and TB).

Looks like the LS2 TP sensors may be putting out a higher voltage at WOT than those in the 02 TB. Could cause the ‘02 TAC to see what it thinks is WOT voltage before the TB is physically there.

From the manuals:


LS2

The TP sensors are used to determine the throttle plate angle. The TP sensors provide the ECM with a signal voltage proportional to throttle plate movement. The TP sensor 1 signal voltage at closed throttle is above 4 volts and decreases as the throttle plate is opened. The TP sensor 2 signal voltage at closed throttle is below 1 volt and increases as the throttle plate is opened.


‘02 78mm
The TP sensor mounts on the side of the throttle body opposite the throttle actuator motor. The TP sensor is actually 2 individual TP sensors within one housing. Separate signal, low reference, and 5-volt reference circuits are used to connect the TP sensors and the TAC module. The TP sensor 1 signal voltage increases as the throttle opens, from around 1.0 volt at 0 throttle to above 3.5 volts at 100 percent throttle. TP sensor 2 signal voltage decreases as the throttle is opened, from around 3.8 volts at 0 throttle to below 1.0 volt at 100 percent throttle.


What voltage is the LS2 90mm showing at WOT? Could this be corrected by adding some resistance to the TP outputs or the 5V reference circuit?

Also from the manual- the TAC uses a PWM voltage to operate the TB motor.

 

Keep in mind that the Corvette/GTO with the same throttle body is getting the full 100% opening of the throttle blade. The SSR gets 83% TPS and the C6/GTO gets 88%, it has nothing to do with the throttle body. All 3 (C6/GTO/SSR) of the 2005 Computers are the same hardware yet use a slightly different operating system, you can exchange one for the other with a full OS flash. Chris at HP Tuners is looking into the issue, they may need to build another table for the relationship between the TPS% and ETC% this way you will be able to enter a value and get results.

 

Glad I bought HP Tuners (rev 2.1.8)... and real happy to see you guys working with them to get this issue worked out.

Bill

 

Bill - You know they have 2.1.10 out already right?

 

Yes, I'll download the newest rev when HP Tuners gets this fixed... I haven't really started playing with the software yet

Bill

 

Just checked out the 90mm LS2 TB. Sensor voltages for throttle plate held fully closed to fully open go from: .55V-4.55V(TPS1) and 4.43V-.45V(TPS2)

Does someone have a stock 02 setup(with the connector shown below) to compare to? Ground the -ve on your voltmeter and probe the TPS1 and TPS2 terminals/wires with the positive lead while manipulating the throttle plate with the key in the run position. I did the testing with the connector off and a couple of wires running between the high/low ref terminals on the connector and corresponding pins on the TB(the LS2 only has 1 high and 1 low ref circuit). Didn't want to damage the wires/connector.