Starts running rich. In limp mode and TPS codes
My 05 chevy trailblazer has progressively gotten worse seemingly with colder weather. In the summer I had intermittent issues where it would not start right in the morning. It would run really really rough. Smoke out the back, smells of gas, check engine light on and limp mode light on. Codes related to tps and or throttle actuator show on scan tool. However usually all it would take to start normally is to shut it off and start it back up once or twice maybe 3 times. I tried cleaning and then changing the the throttle body. May have improved for a short time but always went back soon enough. Cleaned but haven't tried changing yet maf sensor and map sensor. Also added new ground cables to body, frame, and engine block. Also disconnected battery several times to reset computer. None of this helped. Now in the midst of much colder weather it has gotten so much. Now it does it every morning and restarting doesn't do the trick anymore. I just have to keep running it, restarting it for over an hour before it will finally start right. But once it does its completely fine for the rest of the day and the codes and lights will go away. Btw codes are p2101, p2176, and p1516. Sometimes other ones may show up. I remember at least once a code relating to throttle pedal sensor high or low voltage. Something like that. Computer maybe? Oh and btw I changed the throttle body twice and then tried going back to the old ones too so in pretty sure it's not the tps. Oh ya and I hooked up my scan tool one time when it was doing this and got very strange live data readings. I will upload
Comments
Both the P2101 and the P1516 are looking at the throttle TPS signals and comparing them to each other as well as to where the engine controller software expects the throttle to be at both with no command, and with regards to the measured airflow. The throttle should be sitting at about 20% with no command and be able to be moved against spring pressure in both directions. The computer has to command the throttle to close for idle speeds and command the throttle to open for higher engine loads. What do the TPS 1 and TPS 2 sensors read cold, key on engine off? What does the actual throttle position pid show? If someone moves the APP (gas pedal) key on engine off, does the throttle body move in relation to the APP signal changes? With the key off, can you push the throttle plate both towards the closed position and towards the open position and does it return back the rest position approximately 20% open?
The P2176 minimum throttle position not learned makes sense simply because the system has already detected a fault (P2101 and/or P1516) and blocks that function from running.
To understand the P2101 and P1516 better, the measured airflow is either greater than what is expected, and that would cause the engine control module to calculate a longer injector pulse-width and deliver more fuel to the engine causing a rich condition. OR. The measured airflow is less than is expected, then the injector pulse-width would be shorter, and the engine would be lean. Since this isn't in closed loop operation yet it would tend to run pretty poorly.
thecardoc3 thank you for your response. A few days before this post I had posted the same thing but much longer more descriptive and detailed but it wasn't getting any responses. I figured it was too long and people weren't wanting to read it all. As of last Thursday I'm home from work as I've injured my knee. This also makes it harder for me to do any work on the car tho even getting in and pressing the pedal. But anyway the main thing I want to convey is that these scan tool live data readings that your mentioning and how they are a result of being in open loop. I only experience this when the starting problem is happening. And it will stay that way until it clears up. If I press the gas pedal the tps does not go up unless if I pretty much give it full throttle then it will jump up to 70 or something. Also when I press gas pedal spark advance will jump around in the negatives going up to around -15% periodically. Remember when I'm experiencing this issue it is also always in limp mode. However if I turn it off and turn it back on and now suddenly it decides its happy. It'll start fine, no limp mode, no check engine light, no running rough, no trouble codes, no "open loop" live data readings. They will now be back to normal ranges. I don't quite remember if I'm able to move the throttle blade by hand in cold key position. I feel like it doesn't let me but can't say for sure. Also I don't know if the blade opens by pressing the pedal with the engine not running. I haven't been able to observe that by myself. But I'm pretty sure my scan tool doesn't let me view live data with the engine off. I will check all these things asap. But you mentioned something about TPS1 and TPS2. I don't know anything about that. I only see one 1 tps reading on my scan tool. And what is pid?
I appreciate the help. I do have another more expensive scan tool. It was $300 or so from "Innova" or something like that I think. I bought it specifically because it had the ability to bleed the abs module. I think other than that it's capabilities are almost exactly the same but I will check all this stuff asap.