My Chevy Trailblazer is sputtering in the morning, P0171 Code has been coming up?

I had the same problem on my trailblazer, having made a complete diagnosis of pcm and have everything cleaned and remplcé the probe that returned code (P0171) accordingly I checked the operation of the electronic control with manual 'vehicle workshop. It turns out that the injection time is controlled in proportion to the engine temperature. So I tested the temperature sensor (new) and me have noticed that the resistance of this one was 3486 ohms to 371 ohms cold and hot (90 ° Celsius). The specifications of the CFM indicated information received should not be-lower to 470 ohms, 371 ohms to the impoverishment of the mixture is such that the pcm can fix it. Solution I have developed: I installed a variable resistor with a value of 10 to 100 ohms bridged in series on the circuit of sencor (it's very easy to do: cut the black wire upstream of the outlet and is welded this resistance), then with an ohm meter, I rule this resistance to 78 ohms which gives me a total value of 449 ohms hot (90 °). I started my engine and deleted fault codes (po171 and p0138) since this code is not income, and missed more unstable idling and over mistfire. It is imperative to use a variale resistance that can adjust ave a screwdriver to the LIB Leplus possible end setting including the setting of pollution.

With my 2006 Trailblazer I6 I had had the P0171 code on and off for awhile, but it eventually became a permanent thing. Both the method of spraying carb cleaner around and the use of a smoke machine indicated that the intake manifold was leaking. I decided to just tighten the bolts and see if that would solve the problem instead of replacing the manifold gasket. There are ten bolts and the ones closest to the front of the engine were not loose, but as I moved further back the bolts became progressively looser. Towards the middle of the manifold the bolts were definitely loose requiring perhaps a quarter turn to tighten them, the ones toward the rear took perhaps a full turn, and the very last one probably two full turns. I used a variety of 1/4" drive tools to get the job done., including a variety of extensions including wobbler extensions, universal joint, and regular and 10mm deep socket. I did unbolt the ECU to improve access, as well as removing the large vacuum hose going to the brake booster. The front ones would be much easier if the alternator was removed, but I left it on. I also disconnected the battery because toward the rear of the engine the hot terminal of the starter is fairly close to where you will be working with your sockets. Each bolt posed its own particular challenges. I suggest you do not do this when you are pressed for time. The problem is solved!