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2nd Generation
P0171 but not running lean?
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<blockquote data-quote="Vinnie_B" data-source="post: 16817323" data-attributes="member: 201678"><p><strong>P0171 - System to Lean (Bank 1)</strong></p><p><strong></strong></p><p><strong></strong></p><p><strong>Check the following as a possible cause for this DTC:</strong></p><p></p><p></p><p>Air Measurement System</p><ul> <li data-xf-list-type="ul">MAF sensor (contaminated, damaged, malfunctioning, etc.)</li> </ul><p>Fuel System</p><ul> <li data-xf-list-type="ul">Fuel pressure regulator (leaking, malfunctioning, etc.).</li> <li data-xf-list-type="ul">Fuel filter plugged, dirty.</li> <li data-xf-list-type="ul">Fuel pump (weak, check valve leaking, etc.).</li> <li data-xf-list-type="ul">Leaking/contaminated fuel injectors.</li> <li data-xf-list-type="ul">Low fuel pressure or running out of fuel.</li> <li data-xf-list-type="ul">EVAP canister purge valve leaking (when canister is "clean").</li> <li data-xf-list-type="ul">Fuel supply line restricted.</li> <li data-xf-list-type="ul">Fuel rail pressure sensor (incorrect reading).</li> </ul><p>Air Induction System</p><ul> <li data-xf-list-type="ul">Air leaks after the MAF.</li> <li data-xf-list-type="ul">Vacuum Leaks.</li> <li data-xf-list-type="ul">PCV system (leak, valve stuck open, etc.)</li> <li data-xf-list-type="ul">Improperly seated engine oil dipstick.</li> </ul><p>Exhaust System</p><ul> <li data-xf-list-type="ul">Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets, etc.).</li> </ul><p>EGR System</p><ul> <li data-xf-list-type="ul">EGR valve tube/gasket leak</li> <li data-xf-list-type="ul">EVR solenoid vacuum leak</li> </ul><p>Secondary Air Injection</p><ul> <li data-xf-list-type="ul">Damaged/malfunctioning secondary air injection system (mechanically stuck valve).</li> </ul><p></p><p>* View Freeze Frame Data to determine operating conditions when DTC was set. Observe LONGFT1 and 2 PID'S</p><p></p><p></p><p></p><p><strong>Obtain Freeze Frame Data</strong></p><p></p><p>Freeze Frame Data can be helpful in duplicating and diagnosing adaptive fuel concerns. This data (a snapshot of certain PID values, recorded at the time the DTC was stored in Continuous Memory) is helpful to determine how the vehicle was being driven when the fault occurred, and can be especially useful on intermittent concerns. Freeze Frame Data, in many cases, can help to isolate possible areas of concern as well as rule out others</p><p></p><p></p><p><strong>Using the LONGFT1 and LONGFT2 (dual bank engines) PIDs</strong></p><p></p><p>The LONGFT1/2 PIDs can be useful for diagnosing fuel trim concerns. A negative PID value indicates that fuel is being reduced to compensate for a rich condition, while a positive PID value indicates that fuel is being increased to compensate for a lean condition. It is important to know that there is a separate LONGFT value that is used for each rpm/load point of engine operation. When viewing the LONGFT1/2 PIDs, the values may change a great deal as the engine is operated at different rpm and load points. This is because the fuel system may have learned corrections for fuel delivery concerns that can change as a function of engine rpm and load. The LONGFT1/2 PIDs will display the fuel trim currently being used at that rpm and load point. Observing these changes in LONGFT1/2 can help when diagnosing fuel system concerns.</p><p></p><p></p><p></p><p>Lightning Fast<img class="smilie smilie--emoji" loading="lazy" alt="⚡" title="High voltage :zap:" src="https://cdn.jsdelivr.net/joypixels/assets/6.6/png/unicode/64/26a1.png" data-shortname=":zap:" />Electrical Automotive Repair LLC</p><p>PM Me or <a href="mailto:Lightning_Fast@comcast.net">Lightning_Fast@comcast.net</a></p><p>Website: <a href="https://www.lightningfastelectricalautorepair.com/" target="_blank">Lightning Fast Electrical Automotive Repair LLC</a></p><p>Remote or Local (On Site) Technical Repair</p></blockquote><p></p>
[QUOTE="Vinnie_B, post: 16817323, member: 201678"] [B]P0171 - System to Lean (Bank 1) Check the following as a possible cause for this DTC:[/B] Air Measurement System [LIST] [*]MAF sensor (contaminated, damaged, malfunctioning, etc.) [/LIST] Fuel System [LIST] [*]Fuel pressure regulator (leaking, malfunctioning, etc.). [*]Fuel filter plugged, dirty. [*]Fuel pump (weak, check valve leaking, etc.). [*]Leaking/contaminated fuel injectors. [*]Low fuel pressure or running out of fuel. [*]EVAP canister purge valve leaking (when canister is "clean"). [*]Fuel supply line restricted. [*]Fuel rail pressure sensor (incorrect reading). [/LIST] Air Induction System [LIST] [*]Air leaks after the MAF. [*]Vacuum Leaks. [*]PCV system (leak, valve stuck open, etc.) [*]Improperly seated engine oil dipstick. [/LIST] Exhaust System [LIST] [*]Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets, etc.). [/LIST] EGR System [LIST] [*]EGR valve tube/gasket leak [*]EVR solenoid vacuum leak [/LIST] Secondary Air Injection [LIST] [*]Damaged/malfunctioning secondary air injection system (mechanically stuck valve). [/LIST] * View Freeze Frame Data to determine operating conditions when DTC was set. Observe LONGFT1 and 2 PID'S [B]Obtain Freeze Frame Data[/B] Freeze Frame Data can be helpful in duplicating and diagnosing adaptive fuel concerns. This data (a snapshot of certain PID values, recorded at the time the DTC was stored in Continuous Memory) is helpful to determine how the vehicle was being driven when the fault occurred, and can be especially useful on intermittent concerns. Freeze Frame Data, in many cases, can help to isolate possible areas of concern as well as rule out others [B]Using the LONGFT1 and LONGFT2 (dual bank engines) PIDs[/B] The LONGFT1/2 PIDs can be useful for diagnosing fuel trim concerns. A negative PID value indicates that fuel is being reduced to compensate for a rich condition, while a positive PID value indicates that fuel is being increased to compensate for a lean condition. It is important to know that there is a separate LONGFT value that is used for each rpm/load point of engine operation. When viewing the LONGFT1/2 PIDs, the values may change a great deal as the engine is operated at different rpm and load points. This is because the fuel system may have learned corrections for fuel delivery concerns that can change as a function of engine rpm and load. The LONGFT1/2 PIDs will display the fuel trim currently being used at that rpm and load point. Observing these changes in LONGFT1/2 can help when diagnosing fuel system concerns. Lightning Fast⚡Electrical Automotive Repair LLC PM Me or [EMAIL]Lightning_Fast@comcast.net[/EMAIL] Website: [URL='https://www.lightningfastelectricalautorepair.com/']Lightning Fast Electrical Automotive Repair LLC[/URL] Remote or Local (On Site) Technical Repair [/QUOTE]
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P0171 but not running lean?
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