So, I changed out my TB, did all the relearn processes, changed out the accelerator pedal assembly, and so far and it's still throwing the same code and doing the same thing (little to no acceleration). I checked all the wiring and harnesses and everything seems to be in good shape. I cleared out the codes, reset battery, ecu, etc. What could be the issue? I have a cold air intake on it, would that correlate to this in any way? What else should I do?

 

This code pops up for me occasionally, and has since I started driving my car in February. I lose all throttle control and can only idle until I clear the code (I use Torque for Android). I have a 5th gen with a 2014 motor that I swapped earlier this year/late last year. I suspect I need to hard wire my TB harness to the plug rather than use the Nisformance pigtail kit that I presume is giving me grief. That said, I just clear the code, pop the hood, jiggle the harness a bit and keep on driving until it happens again, which might be 10 mi down the road, or next month. Someday when I'm not too lazy I'll get to wiring it properly.

I originally suspected my accelerator pedal was the culprit, so I coughed up $155 for a new OEM unit and it was fine for a while but was not the definitive resolution. My TB is less than 55k mi old, so I'm not going there until I hard wire. I can even wiggle the harness and notice an RPM change. So for me it's an electrical connection that I'm too lazy to fix right now. This code will pop up randomly, and is usually coincidental with a bump, a launch at a light, etc., all things that jar the harness.

There are only three things it could be: A harness/electrical connection, accelerator pedal, or throttle body. Good luck.

 

Just bought a new throttle body from the dealership and slapped it in, reset codes/battery, and did the relearns. All was well for about 10 miles, then it happened again. Was idling at a light and I almost stalled, gassed it a few times (with little to no response) and CEL popped up. Put the car in neutral and did the x2 cycle relearn. Checked the codes and it was still a P2135 and P1271. I already swapped the oem pedal with a remanufactured one from the junkyard, but I bought a new oem pedal from the dealership just in case and it should be coming in within a few days. If none of this solves it, could it be the wiring? How can I test it? What else could it be? I read about the ECM sending out improper voltage to the pedal/tb as well somewhere, how can I confirm?

 

Get a copy of the FSM and start the work flow for each code. It will walk you through testing the harness and connectors and voltage values for the different components. Looks like P1271 is specific to the throttle pedal assembly but cannot find that code in my '03 FSM. Looks like it's also related to bank 1 O2 sensor, which fits your symptoms.

 

Got a little impatient, and I ended up getting a new accelerator pedal sensor from Advance Auto just for sh*ts and giggles. Swapped it out and did all the relearn procedures. 10 miles so far with normal acceleration and idle (and some hard pulls solely for diagnostic purposes ). So far so good, knock on wood...

 

It's in the pedal sensor, not TB. I had that issue and solved it by opening the TPPS and re-soldering all joints inside. Since then 2 years no prob.

 

Alright so, lots of new developments.
Yesterday, I got home excited to finally drive around my newly fixed car... except not. As soon as I started it up, I got a terrible vibration and a flashing CEL. No acceleration at all. Pulled codes and it turned out to be the same P2135 code and a P0304 (Cylinder 4 misfire). Put a new coil in cylinder 4 and it ran and drove great for about 25 miles with no CEL. After parking it for an hour, I started it up and got a CEL. Pulled the P2135 again. I then decided to clear out the ECM by leaving the negative terminal of the battery unplugged for 24 hours. About 26 hours later, I came back and the code was still there (even after doing the relearns). This time, no response from the pedal. Whats new about now is that I also got a P1122 code for the Throttle relay. Where is the throttle relay?

 

It's in the FSM.

What happened to the P1271 code? Sounds like you've at least narrowed down your issues. Just a matter of correcting them now. Piece of cake.