Is a subaru outback 2002 2.5 engine, hard to start cold and running rough under acceleration stall when push accelerator pedal and sometin]mes die no power. codes P0171 and P0130

SOURCE: 90 Subaru Loyale Engine Miss

The simple solution will cost u about $20. Change out the Coolant temp sensor. Some people call them the master sensor,because they control so many things. Like the operation of your engine cooling fan, your on board computer takes readings off of this thing,and it not only controls your fan,but your FUEL. This little thing can cause all kinds of issues. Like over heating, running to rich or to lean. It can act like you have waterin your gas tank, or rotten varnish gas.it can drive you nuts. When you start hour motormin the morning this little sensor senses the temp ( of coarse) and tells the ECM the temp,in turn the ECM provides a richer fuel mixture when your car us cold.(modern choke if you will. The ECM also regulates how long the injector pulses are as well. As your engine warms up, this sensor tells the ECM, if it's working correctly,that the coolant is getting warmer as leans out your fuel mixture. This sensor can cause all kinds of havoc. Like it will start sometimes ok and at other times it won't or if it does it will be real heavy and want to die. Sometimes feathering the pedal will keep it alive but it will be stumbling to stay on and often die. Other times it will drive fine,then it will start bucking at all speeds,like it's loading up, or running to rich. This sensor can cause your engines fan not to come o. And cause overheating.it can also cause the fan to run when it shouldn't be. I had all of these problems,and rally thought that I hD some old gas a d it had started to varnish up everything, as my Subaru had sat for a couple of weeks while I changed out all of the wheel bearings.but after some detective work and a lot of reading I came to the conclusion that the culprit must be this sensor.I changed it out and now it runs great, and when I park it in the driveway and it reaches temp the driverside fan kicks on now. Can't remember the last time I heard it come on. Lol. The passenger side fan should come on when your AC is turned on, just so you know. And make sure when you put your filter cover and intake hose back on to get them on correctly, or you will get a resonating hum from hour air cleaner. The part is cheap, getting things out if the way to get to the sensor a little tuff, but it will I'm sure solve your problem. Good luck.

SOURCE: Car won't start and floods

Locate your vehicle's computer connector (ALDL), most are on the lower driver's side. In some vehicles you might need to look around a little, on the passenger's side, and around the center console under a plastic cover. For more information, check your owner's manual. This device gathers information that was stored in your carsECM. This information ortrouble code can inform you the system or sensor that is malfunctioning. Look up the code in our diagnostic trouble code chart. After repairs have been made use the code scanner to clear trouble codes and recheck system. B. Testing Fuel Pressure. Test for proper fuel pressure with a fuel pressure gauge. Connect the gauge to the test port on the fuel rail. Fuel pressure reading's very depending on the system your in our vehicle, but most throttle body injection cars (TBI) are between 13 psi and 17 psi. and most (DPI) direct port injection systems are between 40 psi and 55 psi. To find out your vehicle system fuel pressure consult arepair manual. If little fuel pressure is present the fuel pump needs to be replaced.

C. Test for Weak Ignition Spark. A weak ignition system can be a sign of a failing ignition component. Remove spark plug wire and insert an extra spark plug into end of wire, attach spark plug to engine ground then crank engine. You should observe blue spark between spark plug gap. If a yellow spark is observed, your ignition coil is weak and needs to be replaced. If your spark is not consistent you may need a ignition module.

D. Inspect the Main ECM Relay. If the ECM relay fails it will shut down the engine management system. This relay carries high amperage and is prone to failure. To test install new relay then test drive to recheck symptoms.

E. Testing the Ignition Switch. This test requires a electronic test light. When vehicle dies test the power side (+) of your ignition coil with the key on, the test light should illuminate. If your test light is not lighting suspect your ignition switch or ignition relay. To trouble shoot this condition you will needwiring schematic for your car.

SOURCE: codes for 2001 subaru

P0130----- 02 sensor circuit on bank #1 sensor #1
P0171------System too lean bank#1
The oxygen sensor on bank #1 needs a new one. If you have a V6 engine, the 02 sensor is screwed into the exhaust pipe up near the exhaust manifold on the same side #1 spark plug is, that's bank #1
I don't have my manual at the moment, so I can't tell you exactly where it is.
The sensor down by the catalytic converter is sensor #2 you don't want that one.

SOURCE: 2001 subaru outback loss acceleration when engine

I cannot say for sure on a subaru, but I have seen similar problem before. On a gm vehicle, if the engine temp sensor that feeds the computer either goes bad or does not read right, it can cause poor performance when cold and sometimes dying problems too.

Kevin Blair

• 196 Answers
• Posted on Feb 25, 2013

SOURCE: 1997 subaru Impreza sport won't stay running . stalls after minute replaced Fuel pump,filter spark plugs wires ,cleaned injectors checked fuel pressure what next

check your grounds. I find many easy fixes by cleaning all the grounds around the engine bay. I would also check the ground at the fuel pump connector that wiring is prone to corrosion and breakage