Question about 2003 GMC Yukon XL

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2003 Yukon. The engine light kept staying on. Changed all 4 02 sensors, all spark plugs. All spark plug wires. Now engine light is off and it runs smooth except every three or four days, I will start it up after not running for a few hours and the motor runs very rough and does that for a while. i check it with a diagnostic, it says mutliple misfires, code PO300. Then I erase the code. Then strangely the engine runs smooth. it does that for a few days and then same problem again. I'm stumped.

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Replace the fuel pressure regulator.

Posted on Jan 25, 2011


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1 Answer

Car stop running just cut off.could it be the starter.

No the starter has nothing to do with your car staying running you should check fuel issues fuel pump injectors regulators. Also most likely check ignition components spark plugs spark plug wires distributor cap and rotor or coil if equipped either or and check coil pick up sits underneth coil packs i would go to advanced auto parts and they can check coil pick up and coils or you can by pulling out spark plug and putting it back in wire set spark plug next to engine block if you see blue spark coil is good if orange bad not hot enough to ignite gasoline. is your check engine light on if so get codes read for free at autozone or advanced auto could also be crankshaft postion sensor or camshaft postion sensor lmk if it helps. if it helps please leave 4 star reviw and good comment thanks

Sep 02, 2011 | 2003 Mercury Grand Marquis

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I have a 2003 yukon Problem with the GMC Yukon XL

What size engine ? 4.3 L vortex P0300 random misfire code is usually associated with vacuum leaks , but could also be low fuel pressure , plugged fuel filter , fuel pump problem , clogged injectors etc... doing fuel pressure an flow testing would confirm or eliminate that as a problem . Fuel injector balance testing would confirm or eliminate clogged injectors .

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My cougar is running like **** i have replaced all the co2 sensors and the egr value. the car has poor accleration and chugs until i hit the drive gear. the engine light stays on but when i step on the gas...

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Oct 04, 2010 | 1999 Mercury Cougar

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My 2003 GMC Sierra idles rough and cut off sometimes when turning.Replaced fuel filter and changed plugs.engine light stays on.Which 02 sensors do i need to replace first? Before converter or after...

Before replacing the O2 sensors, I would check the fuel pressure. You may also try to have someone pull a trouble code from the powertrain control module to verify why the engine light is on. Do not replace any parts until this is done, otherwise your going to be guessing at the root cause, and it will get expensive with part replacement.

May 11, 2010 | 2003 GMC Yukon XL

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Can't get metal spark plug covers back in to place

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May 15, 2009 | 2004 GMC Yukon

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Power and fuel mconsumption

If you replaced the plugs, did you replace the plug wires. Even though they are short wires from the coil to the plugs they can go bad. How is the air filter? Have you replaced the fuel filter?

You have four oxygen sensors on your truck. one on each side pre catalytic converter and one after each converter. It is a very pricey replacement because all of the O2 sensors are four wire.

If you change the sensors, your pcm (vehicle computer) will detect the change in readings very quickly. If you really want to ensure the computer completely relearns you need to disconnect the ground for at least 10-30 minutes. When you reconnect the battery the computer will return to its baseline from the factory. It will immediate begin the adaptive learning process to perform in accordance with your driving style.

Another thing to consider is cleaning the mass air flow sensor. This is a very delicate piece of sensor and requires a special cleaner. STP and GUMOUT both sell a specific product for the cleaning of the MAF. Follow the directions. I would be especially concerned if your usinga K & N air filter as the oil from the filter will sometimes coat the MAF and resulting in bad readings.

Good luck.

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Check engine light 2004 GMC Yukon

When my check engine light went on, it was a oxygen sensor

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Have a 2001 yukon 4wd 5.3

not at all and when changing your spark plug there is no reason not changing the spark plug wires too..

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1 Answer

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Bank 1 Sensor 1
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I would check for vacuum leaks, maybe intake or brake booster

Dec 16, 2008 | 2003 GMC Yukon XL

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