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03 chevy tahoe po300 code

This is a discussion on 03 chevy tahoe po300 code within the Technical / Maintenance forums, part of the General Discussion category; I have a 03 chevy tahoe 4wd, with the 5.3 flex fuel . My truck died out one day turning ...

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    03 chevy tahoe po300 code


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    I have a 03 chevy tahoe 4wd, with the 5.3 flex fuel . My truck died out one day turning into the parking lot at work , when i can get it started it runs very very rough , to the point it is not driveable . i hooked a scanner up to it and got the code po300 multi cylinder misfire. it seemed like it wasnt getting gas , so we replaced the fuel filter that did not work. Everyone said its the fuel pump so i changed that . that did not work either . I am stuck not sure what to do next . Any suggestions???
    Last edited by JoesTahoe; 11-11-2008 at 07:23 PM.

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    Registered User Stevens07's Avatar
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    Re: 03 chevy tahoe po300 code

    Clean the MAF sensor and see if that changes anything.

    Steven


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    Re: 03 chevy tahoe po300 code

    i will try that as soon as i get to the shop in the morning thanks.. someone also said i might need to disconnect the battery cables to reset the computer cause it might be holding the codes , does that sound right ?

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    Registered User ripsass's Avatar
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    Re: 03 chevy tahoe po300 code

    Yep, if you don't clear the codes (by unhooking the batt) after fixing something, the computer will still be trying to compensate for a problem that is not there anymore.
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    Re: 03 chevy tahoe po300 code

    Ok great thanks . i will try it as soon as i get to work in the morning .. i will let you know how it goes. thanks!!!

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    Re: 03 chevy tahoe po300 code

    Quote Originally Posted by ripsass
    Yep, if you don't clear the codes (by unhooking the batt) after fixing something, the computer will still be trying to compensate for a problem that is not there anymore.
    Not necessarily. It can but not always.


    A P0300 is usually caused my spark or fuel. A dead MAF sensor should set a code but you can always just unplug it and see if it will run in speed density mode. If it does you need a MAF sensor. I guess we could say your fuel pressure is good. I'm not 100% sure if the fuel pressure regulator is still on the rail on an 03 or not. I know in 04 it went in the tank along with the filter. It would be work looking at if it has one on the drivers side fuel rail. Pop the vacuum hose off and look for fuel running out. If it does its shot. Other then that a broken wire or mice damage is about it to cause a sudden P0300.
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    Re: 03 chevy tahoe po300 code

    well itried disconnecting the battery that didnt seem to work , no it will idle for about three seconds on it own . before it wouldnt even do that . this afternoon i am going to try to clean the maf sensor and see if that does anything . i will let you know what happens later today .

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    Re: 03 chevy tahoe po300 code

    Couple things to try. You might need to replace the plugs if one of them is fouled up and not firing. The plug wires also might need to be replaced. To diagnose this, start the truck in a very dark area (unplug the engine bay light if you have to), grab a spray bottle filled with water and mist the wires (mist, not soak). If you see tiny blue arcs all over the place, your wires are shot and causing your problem.

    I had P0300 in a Cadillac that was caused by a clogged fuel injector. The way to diagnose this is to put the tip of a slot screwdriver along the side of the injector housing when the truck is running and then stick your ear to the end of the screwdriver handle while plugging your other ear. If the injector is working properly, you will easily hear a regular click, click, click. I know it sounds a little goofy, but it was pretty obvious which injector wasn't working. In my case all I had to do to get that injector working again was to tap it a couple times with a medium size metal object...6" ratchet extension. Use a little common sense here...if you smash the injector, you have another problem. If tapping the thing doesn't work, you may have to replace the bad injector.

    If none of that does the trick, you may have a more severe problem like lack of compression which someone else will have to tell you how to diagnose/fix. Good luck. P0300 codes are a pain to track down...too generic of a code.

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    Re: 03 chevy tahoe po300 code

    Generally I always start by looking at the spark plugs.
    If they are old, that could cause something like this.
    I honestly don't think if they are bad or going bad that is your only problem, as it runs so bad.
    You may want to check to make sure the cam and crank senors are both mounted securely. If they move or misread intermittently, it would be a though.
    Like everyone else has been saying, checking plug wires too, I would check the coils, and the injectors.


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    Re: 03 chevy tahoe po300 code

    Well I have replace the spark plugs today , they all looked kinda bad, that still didnt help the problem .. so i have changed the fuel filter , fuel pump, spark plugs , cleaned the throttle body, cleaned the maf sensor . Still running very rough and still cant drive the truck. the spark plug wires didnt look bad , but i will try checking them in the dark with a spray bottle . The one major thing that confuses me is that the truck just died suddenly with no warning at all , before it happen it was running great . So if anyone has more ideas it will definitly help . Thanks

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    Re: 03 chevy tahoe po300 code

    I Found This On GM Website I believe It PERTAIN To You
    #05-06-04-029A: Flexible Fuel (RPO L59) Rough Idle, Misfire, MIL DTC P0300 (Install Intake Manifold Gaskets with Teal Green Gasket Material) - (Jun 24, 2005)

    Subject: Flexible Fuel (RPO L59) Rough Idle, Misfire, MIL DTC P0300 (Install Intake Manifold Gaskets With Teal Green Gasket Material)

    Models: 2002-2004 Chevrolet Silverado, Suburban, Tahoe
    2002-2004 GMC Sierra, Yukon, Yukon XL
    with 5.3L Engine and Flexible Fuel (VIN Z -- RPO L59)
    This bulletin may apply to the following engines using regular fuel: 4.8L, 5.3L, 6.0L (VINs V, T, P, U, N -- RPOs LR4, LM7, LM4, LQ4, LQ9).

    This bulletin is being revised to add additional diagnostic information. Please discard Corporate Bulletin Number 05-06-04-029 (Section 06 -- Engine/Propulsion System).

    Important: Always begin your diagnosis with the Diagnostic System Check - Engine Controls (SI Document ID #1289827) for any MIL or driveability concern. The Diagnostic System Check directs you to the next logical step in your diagnosis. Follow the instructions in this bulletin should the rough idle, misfire, or DTC P0300 diagnostic procedure point to an air leak in the intake manifold gasket. Following the published diagnostic procedures will improve diagnostic accuracy and support our fix it right the first time approach.
    Condition

    Some customers may comment that the vehicle may have a rough idle, misfires and/or a MIL illuminated with a stored DTC P0300.
    Cause

    The L59 engine is calibrated for ethanol fuel (E85). Due to the low volatility of ethanol, the PCM provides higher fuel flow through the injector, which may pool on the upper manifold to head gasket material. Over time (usually 12 months and longer), the gasket material may degrade resulting in an unmetered air leak.
    Correction

    Replace the upper intake manifold gaskets with the teal green gasket material, P/N 89017589.

    Important: Do not replace the upper intake manifold gaskets with the original orange gasket material, P/N 17113557.

    Inspect Intake Manifold to Cylinder head Deck for Warpage

    Important: The intake plenum should also be checked for excessive warpage that may cause an uneven clamping pressure of the seal. If the plenum is found to be warped it will need to be replaced. Service Information states, "An intake manifold with warpage in excess of 3 mm (0.118 in) over a 200 mm (7.87 in) area should be replaced." Intake warpage is measured at the gasket sealing surfaces and should be measured within a 200 mm (7.87 in) area. This measurement is across only two of the intake runner port openings. Measurements taken across the entire distance of all four intake runner ports will lead to unnecessary manifold replacements.

    Object Number: 492779 Size: SH
    Click here for detailed picture of above image.

    Important: Measurements taken across the entire distance of all four intake runner ports will lead to unnecessary intake manifold replacements.
    1. Locate a straight edge across the intake manifold cylinder head deck surface. Position the straight edge across two runner port openings.
    2. Insert a feeler gauge between the intake manifold and the straight edge. An intake manifold with warpage in excess of 3 mm (0.118 in) over a 200 mm (7.87 in) area is warped and should be replaced. Do not replace intake manifolds with warpage that measures less than 3 mm (0.118 in) over a 200 mm (7.87 in).

    Parts Information

    Part Number


    Description

    89017589


    Gaskets, Upper Intake Manifold (Teal Green)


    ALSO I WOULD SUSPECT A BAD INJECTOR-DO A POWER BALANCE TEST AND SEE WHICH CYLINDER/S IS BAD. ALSO CHECK GROUND ON CYLINDER HEAD.
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    Re: 03 chevy tahoe po300 code

    ok cool , Yeah i seen that also on the intake manifold gasket , i am going to check that . Thanks . How do you do a Power Balance test ??

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    Re: 03 chevy tahoe po300 code

    if you work at a gm delearship you can use a tech 2 and another tester i forget the name of it to test it. More then likely you have a camshaft issue. But hey what do i know.

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    Re: 03 chevy tahoe po300 code

    No i dont work at a gm dealership . I work for a body shop.. Well i will check out theses suggestions and let everyone know what happens. Thanks again for all the suggestions , hopefully something will work.. lol

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    Re: 03 chevy tahoe po300 code

    Even if the intake gaskets are leaking they won't cause it to be undrivable. They tend to only leak when the engine is cool and even then its only on a couple cylinders at most. Do you have spark to all the plugs?
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    Re: 03 chevy tahoe po300 code

    well as far as i know i have spark , i am going to try and check that today .

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    Re: 03 chevy tahoe po300 code

    So I think i might have figured out the problem . I belive its the MAP sensor . i disconnected it and it runs better , still missing some but better . so i am changing that out tomorrow afternoon. I will let you all know what happens .

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    Re: 03 chevy tahoe po300 code

    Did you figure out the issue? I have an 03 tahoe,140k mi, same issues, had to take to dealer, they came up with intake manifold gasket, plugs/wires. Callback stated they still have rough idle. Did the MAP sensor work?

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    Re: 03 chevy tahoe po300 code

    Dealer also stated bad valve spring on #4 cylinder. Intake manifold gasket, plugs, wires and valve spring....picked up truck and its running good, hopefully it lasts.

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    Re: 03 chevy tahoe po300 code

    im working on a 04 chevy express van with this code. it came in with the converters rattling terribly, replaced them test drove all was good. a day later it returned with the same code but converters still good. hooked it up to our shop scanner. found #1 cylinder misfiring badly, has been tuned up with plugs and wires within the last 20,000 miles. swapped plugs and wires on #1. still has the problem. swapped coil packs still has the problem, compression is good. so i dont think its a sticking valve or spring. may try tapping on the injector in the morning. i have unplugged the injector and started the truck runs worse, but mot much. i did at that piont get and injector code but it went away after i plugged it back in as i thought. its very possible it is the manifold i will be checking that tomorrow also.
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