01 Yukon - Throttle Position does not zero

[troysmith80]

I have a 2001 yukon 5.3 and a cheap amazon bluetooth adapter running Torque Light on Android as an OBD reader. 

 

Sometimes torque shows that my throttle position does not go to zero when i lift off the pedal. When i lift off the pedal i've seen readings anywhere from 5-15%. It generally is consistent during any driving cycle. That is, if i plug it in and go for a drive, and the reading is 11% when i lift off the throttle, then it will read 11% every time i lift off the throttle, until I either turn off the truck or maybe disconnect and reconnect the OBD reader. Similarly, if it actually reads 0% when i lift, then it will do so for that whole driving cycle.

 

If I press on the pedal, the reading immediately rises (as opposed to staying constant until i reach 11% pedal input.

 

Question 1: I'm assuming that the throttle position sensor should always return a 0% reading when I lift off the pedal, is that true?

Question 2: Is a bluetooth OBD reader and Torque a reliable / accurate method of getting a reading? I'm guess it is since the actual reading is done in the ECU and torque will simply get the data or it won't, but it probably won't display incorrect data, is that right?

Question 3: Does this indicate a problem, and what should I do about it.

 

Possibly related: Sometimes the engine idles around 1,000-1,100 rpm instead of the more typical 500-600 range. I need to pay more attention to see if this is happening when i'm getting the non-zero throttle reading, i think it may be. The transmission seems somewhat reluctant to upshift, for example, staying in 3rd gear after a climb levels out, possibly because it thinks it's seeing higher throttle position than actual. This may be my mind playing tricks on me.

 

Also, it's hard to be sure due to other variables, but i think that the MPG displayed in torque tends to be lower when I have non-zero throttle reading "episodes".

 

Thanks for any help!

[sefiroxx]

1- under higher rpm, the engine vacuum will hold the throttle open to show for the demand of air
2,3-sounds like you need a new obd scanner

[troysmith80]

Thanks sefiroxx,

1- I'm really only noticing this at zero or near zero throttle, low rpm situations. 

[O_J_Simpson]

Grab a tooth brush and some TB cleaner. Open the butter fly and get after it. All black carbon should be gone from the TB and it will work like new again.

[troysmith80]

I cleaned out the TB several weeks ago, i should have mentioned that. TOday I went out and cleaned up the idle air control, checked the throttle body (still clean), sprayed the MAF with alcohol and i took off the throttle position sensor and looked at it. It looked very clean inside and turns with no resistance. We'll see if any of that made a difference. I put the OBD scanner on there and was showing 0.4% throttle or something like that.