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It's P0171 & P0174 not Pc 171 & Pc174 ! The engine computer has detected a lean condition ! That mean's it's not getting enough fuel or has a vacuum leak , bad O2 sensor ! fuel pump getting weak . fuel pressure regulator weak !
P0171 - System to Lean (Bank 1)
The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to Section 1 , Powertrain Control Software, Fuel Trim for more information.
Air Measurement System
EVAP canister purge valve leaking (when canister is "clean").
Fuel supply line restricted.
Fuel rail pressure sensor (incorrect reading).
Air Induction System
Air leaks after the MAF.
Vacuum Leaks.
PCV system (leak, valve stuck open, etc.)
Improperly seated engine oil dipstick.
Exhaust System
Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets, etc.).
EGR System
EGR valve tube/gasket leak
EVR solenoid vacuum leak
Secondary Air Injection
Damaged/malfunctioning secondary air injection system (mechanically stuck valve).
P0174 - System to Lean (Bank 2)
The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to Section 1 , Powertrain Control Software, Fuel Trim for more information.
See Possible Causes for DTC P0171.
See Diagnostic Aides for DTC P0171
View Freeze Frame Data to determine operating conditions when DTC was set. Observe LONGFT1 and 2 PID(s). Refer to Section 2 , Adaptive Fuel DTCs Diagnostic Techniques for more information.
If it has the original Bosch fuel injection, it will be accessible through the left side wheel well, or through the service hatch in the trunk (boot), and there may be a secondary one inline before it reaches the fuel injection under the hood (bonnet). If the fuel injection has been replaced with an updated one, your guess is as good as mine.
The electronic fuel injection system in your 2007 Toyota Corolla is an extremely technologically advanced, computer controlled, engine fueling system that consists of hundreds of parts, sensors, solenoids, relays and electrical circuits. It also consists of a computer-controlled pump as well as high-pressure lines and fittings that deliver the fuel from the fuel tank to the injectors. The computer system that controlls your fuel injection system has nearly 100,000 times the computing ability of the computers that were on the Apollo space craft that put put man on the moon. To say something as simple as "fuel injection problem" and expect a viable "solution" for your problem is like saying "water problem" at Niagra Falls and expecting somebody to fix it for you.
What kind of "fuel injection" problem? Have you tried interfacing with the computer that controls your fuel injection system? If so, what did it tell you? If not, that would be a real good place to start.
This could be a lot of things, but the first thing I would check is the water temperature sensor that tells the fuel injection system how hot the water in the engine is. If the fuel injection thinks the car is cold, it supplies extra fuel and eventually the engine floods. This should set a check engine light and code, although the code in this situation will usually point to some other component that does not agree with the water temperature sensor rather than to the actual culprit.
The fuel line from the tank, the fuel pump, to the fuel filter and the fuel injection system , pump and injectors must be checked ONE BY ONE.
However the fuel filter must be changed in a span of about at least 10000 miles or much earlier if the fuel has dirt .
A code check can determine your fault and your electrical system must also be looked into.
DTC P0171 is set when fuel trim is driven rich beyond a certain value. Possible causes are: 1. Exhaust system leak. 2. Improper fuel pressure. 3. Fuel injector restricted. 4. Defective heated oxygen sensor No. 1. 5. Defective Manifold Absolute Pressure (MAP) sensor. 6. Defective Engine Coolant Temperature (ECT) sensor. When the air fuel ratio feedback is stable after the engine is at operating temperature and the fuel trim has reached its limit of correction to the rich side. (2 trip logic). Feedback from the HO 2 sensor influences short-term fuel trim and short-term fuel trim influences long trim fuel trim. Short-term values are temporary and not stored when the ignition key is turned off. Long-term values are stored in memory because they are part of the basic injection duration. Long term values affect injection duration in closed and open loop because they are used to calculate basic injection duration. It is important to remember that the actual fuel trim will be the opposite of the DTC. A system too lean, DTC P0171 will mean the ECM is making a + or rich correction. read (and let me know)above data and Freeze Frame by using (example, generic) Scan Tool on # mode 2, etc. Slowly accelerate the engine in the increments shown and record voltage, grams/sec of MAF and SFT, LFT, Injection Pulse, Fuel Pressure, etc. HTH, Vehicle have MAF Sensor?
1) There could be an air lock to the fuel system, try to bleed the system.
2) If the fuel is reaching the injector pump & not supplying to the injectors nozzles thn the pump needs attention.
Hope this helps!
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