Throttle Position

[bstuder11]

So Im tuning an LS2 in a Trailblazer SS and the tps is reading a Maximum of 83% and a Minimum of 24%. Can anyone explain this to me and possibly tell me how I can get the throttle to open to 100%...this is the first LSX motor I have tuned that has done this. Thanks!

[bstuder11]

I read some other threads while I have been waiting (apparently this is a very common issue). The general Consensus seems to be to swith to the ETCTP. Well I did that, and that does make it read 100 at WOT but it still only lets it go down to lilke 15 at closed throttle and the main reason I had this question in the first place is that I had a friend tell me that there is actually a free mod on this engine by removing a throttle blade stop you can allow the blade to open all the way....

[Dieselman]

From what I understand ETCTP is the actual blade position in the throttle body and APP is the voltage from the pedal sensor ie 88% of 5volts is 4.4volts

Someone please correct me if I'm wrong

[bstuder11]

Yeah that's what I read as well. I still don't know why it never zeros out though and I guess imma have to physically look at my blade and see if it's opening all the way later on today.

[Boost]

Same thing in my Cruze (max 84%) as well as several other vehicles I have tuned. Perhaps someone can explain this? I do not think it is a free mod. Also, the tune considers that as WOT already.

[swingtan]

As already stated, the reading of approx. 20% to 80% is the actual voltage reading from the TPS as a percentage of 5V. For some reason, GM decided to change the way the PID worked but they also provided a couple of new PIDs to give you the actual throttle opening %. I use ETCTP, as it was the first PID that gave a true 0-100% reading back when I started.

As for never going to "0", it's because the throttle never completely closes. The only time id does shut completely is at key on and possibly key off. Key on it does a home check, key off it helps kill the motor. At all other times, minimum idle airflow settings will mean the throttle never actually closes, so the TPS will never drop to "0". Remember guys, this is not a directly cabled throttle blade. Never assume the throttle is going to be doing the exact same thing as the pedal is.

Simon.

[bstuder11]

Definately appreciate your input Simon. I am very aware of the drive by wire as I have tuned several and I own the same year H2 with the same set up besides the PCM however it will read 0-100%. Like I said though I'll go check and visually confirm it's opening all the way and forget about it. It runs GREAT, that just had me confused. Again, thanks