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Misfire codes when air conditioning turned on

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2002 buick Lasabrea custom service engine soon light code revi ew says multiple misfire detected


Multiple misfires can be caused by a few different things , intake manifold vacuum leaks , low fuel pressure , basic things like plug wires an spark plugs needing to be changed if hasn't been done already . How many miles on the vehicle ? If over 100,000 K timing chain an gear wear can also cause this . The powertrain control module (PCM) uses information from the ignition control (IC) module and the camshaft position (CMP) sensor in order to determine when an engine misfire is occurring. By monitoring the variations in the crankshaft rotation speed for each cylinder the PCM is able to detect individual misfire events. A misfire rate that is high enough can cause the three-way catalytic converter to overheat under certain conditions. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for 3-way catalytic converter overheating are present.
If the misfire is random, check for the following conditions:
?€¢
System grounds


Ensure all connections are clean and properly tightened.


?€¢
Mass air flow sensor


A mass air flow (MAF) sensor output that causes the PCM to sense a lower than normal air flow will cause a lean condition. Try operating the vehicle within the Failure Records conditions with the MAF sensor disconnected. If the lean or misfiring condition is not present with the MAF sensor disconnected, replace the Mass Airflow Sensor Replacement .


?€¢
Damaged accessory drive belt or driven accessory


A damaged serpentine belt or belt driven accessory can cause engine load variations sufficient to set a misfire DTC.


?€¢
Air induction system


Vacuum leaks that cause intake air to bypass the MAF sensor will cause a lean condition. Check for disconnected or damaged vacuum hoses, incorrectly installed or malfunctioning crankcase ventilation valve, or for vacuum leaks at the throttle body, exhaust gas recirculation (EGR) valve, and intake manifold mounting surfaces.


?€¢
Fuel pressure


Perform a fuel system pressure test. A malfunctioning fuel pump, a plugged filter, or a malfunctioning fuel system pressure regulator will contribute to a lean condition. Refer to Fuel System Diagnosis .


?€¢
Fuel injectors


Refer to Fuel Injector Solenoid Coil Test .


?€¢
Water contamination in the fuel system can cause a single cylinder to misfire as well as cause a random misfire, refer to Alcohol/Contaminants-in-Fuel Diagnosis .


?€¢
EGR system


Check for leaking valve, adapter, or feed pipes which will contribute to a lean condition or excessive EGR flow.


?€¢
Extended idle


Excessive Open Loop operation caused by extended idling or short trip driving may leave deposits on the heated oxygen sensors. The deposits cause oxygen sensors to respond slowly to exhaust oxygen content, affecting fuel control and causing a misfire to be indicated at idle. This condition is not permanent. To determine if this condition is causing the DTC P0300 to set, review the Freeze Frame/Failure Records for DTC P0300. If the DTC P0300 occurs at high engine speeds, the condition described above did not cause the DTC to set. If the DTC P0300 occurs at idle or very low engine speeds and at engine coolant temperatures below 80?°C (176?°F), the condition described above is very likely the cause of the DTC to set. The deposits on the heated oxygen sensors can be eliminated by operating the vehicle fully warm at mass air flows above 15 g/s.

Jun 23, 2016 | Buick Cars & Trucks

1 Answer

My 99 grand prix bucks and jumps in reverse and when idling in drive or park


The codes pretty much explain the bucking and jumping. The engine is obviously misfiring on several cylinders.

With the P0171 code, the lean condition (and therefore, the misfiring) could very possibly be caused by a bad Mass Airflow (MAF) sensor, a faulty fuel pump, a clogged fuel filter, or a HUGE vacuum leak.

However, the P0171 code can also be caused by excess unburned air/fuel mixture going down the exhaust due to cylinders misfiring for other reasons like a faulty ignition coil, ignition module or bad spark plugs (as well as other possibilities).

So, now you are faced with trying to determine if the lean condition is caused by the misfires or if the misfires are being caused by a lean condition. (PROPER DIAGNOSIS REQUIRED)

Mar 24, 2012 | Cars & Trucks

2 Answers

My truck is showing codes 171 and 174. Can you help


P0174 Generic Definition

Fuel Trim Bank Two Condition
- The ECM has detected a rich or lean air/fuel ratio condition on engine bank two

Probable Cause[s]

  1. If bank one and two are set together suspect a fuel pressure condition or MAF sensor fault
  2. Failed HO2S21
  3. Ignition misfire condition
  4. Fuel injector problem
  5. Engine mechanical condition




    P0171 Generic Definition

    Fuel trim bank one condition
    - The powertrain control module uses the oxygen sensor to calculate the air/fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only.

    Probable Cause[s]

    1. If bank one and two codes set together suspect fuel pressure or MAF (Mass Air Flow) Sensor
    2. Oxygen sensor defective
    3. Ignition misfire-repair
    4. Fuel injector problem












      Mar 05, 2011 | 1999 Chevrolet Silverado 1500

      2 Answers

      After going over 40mph the check engine light goes on n it gives the code 440


      How did you read that code on your car? A 92 Accord is supposed to give you pre-OBD honda codes, which are all below 100. Please check the code again and re-post it.

      Jan 04, 2011 | 1992 Honda Accord

      1 Answer

      02 sensor p0136 and cylinder misfire p0300


      Most likely you do not have bad O2 sensor or coil sience you have P0300 code.
      Check for vacuum leaks first , this is very common problem(vacuum leak) , lean mixture will cause misfire. I'm tallking about V6 engine , 4cyl have same problems but for misfire it may have bad coil (they under recall now).
      Also check condition of air mass sensor , if it's dirty ,
      buy air flow sensor cleaner and clean it according to user manual on the can.(air mass sensor can cause
      O2 sensor code)
      Check vacuum hose to fuel pressure regulator.
      There are many more things to check , but that for mechanic shops after you try this.

      Jun 10, 2010 | 2001 Audi A4

      3 Answers

      2003 Ford Ranger 4x4 extended cab- diagnostics checked and got these codes- P0171, P0174, P0300, P0316. Can you tell me what they mean?


      P0171------ system too lean bank#1
      Po174------ system too lean bank#2
      For these 2 codes, try cleaning the maf sensor (mass air flow), that is mounted in the big black hose that goes from the air filter housing to the throttle plate, if it is dirty, that will cause those 02 sensors to send a signal to the computor to lean the air fuel mixture. If cleaning it doesn't work, the sensors will probably need changing.
      P0300---- Random/multiple cylinder misfire
      P0316---- Cylinder misfire at start up---- first 100 revolutions.
      On those 2 codes, you have to do some testing to find out why there is a misfire.
      Possible causes:
      dirty/malfunctioning injectors
      weak coil pack
      fowling spark plugs/wires
      Low fuel pressure

      May 11, 2010 | 2003 Ford Ranger Regular Cab

      1 Answer

      2006 jeep liberty code po304


      P0304 indicates misfire in the cylinders..
      A misfire can be triggered by several situations. inadequate fuel, ignition misfire, insufficient air flow, too much fuel, incomplete compression... If you look at freeze frame data with a scanner you can see what the conditions were when the code was set, this will really help to pinpoint the problem.

      Apr 14, 2010 | 2006 Jeep Liberty

      1 Answer

      The car starts fine when i first turn it on. After driving a lil while the car warms up and i stop somewhere,the store or where ever, turn it off. i come back a couple mins later and it takes a good 3+...


      There can be a misfire too from the cylinders.

      An engine that hesitates, stumbles or misfires when accelerating or when it is under load is an engine that is either sucking too much air, not getting enough fuel or misfiring. If the Check Engine
      Light comes on, you may find any of the following codes:

      • P0171, P0174 Lean fuel condition codes
      • P0120 to P0124 Throttle position sensor codes
      • P0222 to P0229 Throttle position sensor codes
      • P0400 to P0409 EGR related codes

      If there are no misfire codes, a common cause of acceleration stumble is a bad throttle position sensor (TPS). The TPS tells the computer how far the throttle is open. The computer uses this information to determine how much fuel is needed to maintain the correct air/fuel mixture and when extra fuel is needed if the throttle suddenly opens wide.

      Another common cause is dirty fuel injectors. If varnish deposits have built up in the tips of the injectors, they won’t spray as much fuel as they normally do, or will “dribble” fuel instead of
      spraying a fine mist. This creates a lean fuel mixture and conditions that are ripe for stumble and hesitation (also misfire). Look at short term fuel trim (STFT) and long term fuel trim (LTFT) with your
      scantool. If the numbers are high, it tells you the engine is running lean and the injectors need cleaning. Treat mild cases with a high quality fuel-injector cleaner additive. Severe cases require professional cleaning equipment.

      Good luck and rate this.

      Mar 08, 2010 | 1997 Volkswagen GTI

      1 Answer

      Will turn over wont start I would like to check the fuel pump by running a hot wire from the terminal plug in next to the stering column to fuel pump but iinstructions say to hook it to G, but I cant find...


      There can be a misfire too from the cylinders.

      An engine that hesitates, stumbles or misfires when accelerating or when it is under load is an engine that is either sucking too much air, not getting enough fuel or misfiring. If the Check Engine
      Light comes on, you may find any of the following codes:

      • P0171, P0174 Lean fuel condition codes
      • P0120 to P0124 Throttle position sensor codes
      • P0222 to P0229 Throttle position sensor codes
      • P0400 to P0409 EGR related codes

      If there are no misfire codes, a common cause of acceleration stumble is a bad throttle position sensor (TPS). The TPS tells the computer how far the throttle is open. The computer uses this information to determine how much fuel is needed to maintain the correct air/fuel mixture and when extra fuel is needed if the throttle suddenly opens wide.

      Another common cause is dirty fuel injectors. If varnish deposits have built up in the tips of the injectors, they won’t spray as much fuel as they normally do, or will “dribble” fuel instead of
      spraying a fine mist. This creates a lean fuel mixture and conditions that are ripe for stumble and hesitation (also misfire). Look at short term fuel trim (STFT) and long term fuel trim (LTFT) with your
      scantool. If the numbers are high, it tells you the engine is running lean and the injectors need cleaning. Treat mild cases with a high quality fuel-injector cleaner additive. Severe cases require professional cleaning equipment.

      Good luck and rate this.

      Mar 07, 2010 | 1991 Chevrolet Camaro

      1 Answer

      I have a 318i 1998, the engine light came on. i hook up my obd scaner to it and the trouble codes are as follows p1174 (fuel trim adaptation additive bank 1 malfunction,po300 (random/multiple cyl. misfire...


      Sounds like it may be running a bit lean - do basic checks for air leaks in the induction system (such as leaking manifold gasket, loose hose fittings to air flow sensor etc).
      Condition of HT leads also worth a check.

      Jun 07, 2009 | 1999 BMW 318 ti

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