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flashing check engine light

This is a discussion on flashing check engine light within the Technical / Maintenance forums, part of the General Discussion category; hello, i have been experincng some weird things with my 03 5.3l z71. the truck will miss and shutter while ...

  1. #1
    Registered User ballin_z71's Avatar
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    flashing check engine light


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    hello, i have been experincng some weird things with my 03 5.3l z71. the truck will miss and shutter while under load and the check engine light will begin to flash. but after this short duration it will figure it slef out and be fine again??? this used to happen when id leave for work in the morn and hope on the hiway when it was -25 out, the engine light flashed and i checked it with the scan tool and it had no stored codes so i fogot about it, how ever this happend today after work and its no where near -25. anyideas???

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    Registered User Bowtie00's Avatar
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    Re: flashing check engine light

    i would start by checking you intake gaskets
    then i would probably check fuel quality, pressure, volume
    if you do not find the problem,
    have a scan tool at all times and check codes while the check engine light is flashing or check codes with a better scanner

    i would not drive the truck while it is experiencing this fault with the exception of 1)to find out whats causing it 2)verify fix.

    the reason for not driving it is 1) flashing SES light means you are knowingly killing your cats, 2) it might leave you stranded somewhere..... maybe
    2000 Chevy Silverado 1500 4.3L 5 Speed

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    2nd Amendment Supporter mudbuddy's Avatar
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    Re: flashing check engine light

    When the check engine light flashes it means stop NOW and fix problem the flashing means a severe problem is occuring.

    The following may prevent more serious damage to your vehicle:

    • Reducing vehicle speed

    • Avoiding hard accelerations

    • Avoiding steep uphill grades

    • If you are towing a trailer, reduce the amount of cargo being hauled as soon as it is possible

    If the light stops flashing and remains on steady, see "If the Light Is On Steady" following.

    If the light continues to flash, when it is safe to do so, stop the vehicle. Find a safe place to park your vehicle. Turn the key off, wait at least 10 seconds and restart the engine. If the light remains on steady, see "If the Light Is On Steady" following. If the light is still flashing, follow the previous steps, and see your dealer for service as soon as possible
    Last edited by mudbuddy; 03-19-2009 at 04:13 PM.

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    Registered User ballin_z71's Avatar
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    Re: flashing check engine light

    well this sounds worse then i expected, i just figured a simple miss fire, it was doing it around town today, you could feel it miss but the flashin light never came back on. how ever mudbuddy is correct with the hi speeds, hard acceleration and steep hills, its more noticeable under those situations. another after thought is fuel, i tried running hi octane to see if it would asist in economy. could the higher octane do this? like a pre detonation? i filled it last week, and i just filled with reg tonight. these symtoms havent occured prior to this, only on those super cold mornings and at that it happend twice

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    2nd Amendment Supporter mudbuddy's Avatar
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    Re: flashing check engine light

    get the codes read soon.

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    Registered User ballin_z71's Avatar
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    Re: flashing check engine light

    you think dealer would be best? or will any scan tool due, like i said last time i scaned nothing stored?

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    2nd Amendment Supporter mudbuddy's Avatar
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    Re: flashing check engine light

    I would try one of the parts stores that does it free first.

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    Registered User ballin_z71's Avatar
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    Re: flashing check engine light

    alright thanks for tip, ill let you kno what comes up

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    Re: flashing check engine light

    the higher octane shouldn't do it...the higher the octane the higher the temp needs to be to combust

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    Probably on a rig. Colin B's Avatar
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    Re: flashing check engine light

    when my wife's ford escape was flashing it was because of a misfire


    1990 C1500
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    Registered User Bowtie00's Avatar
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    Re: flashing check engine light

    Quote Originally Posted by Colin B
    when my wife's ford escape was flashing it was because of a misfire
    most of the time it is,
    because a misfire is the leading cause of catalytic failure

    but another thing i have seen that will totally destroy your cats as quick as a misfire is a lean condition.
    2000 Chevy Silverado 1500 4.3L 5 Speed

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    Re: flashing check engine light

    I had that almost exact thing happen on my 99 5.7 liter it was cutting out and missing, and the service light would flash when under a load. It turned out to be a cracked spark plug cover. Put a new one on and it was all good. Turned out to be about a $10 fix.

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    Registered User ballin_z71's Avatar
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    Re: flashing check engine light

    i went for a 2 hr drive yesterday, no flashing check engine light, but you sure could feel it miss. is there anyway to diagnose what cyl it could be or do u have to do it the old fashion way

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    Re: flashing check engine light

    Have you checked your ignition system? pull the plugs and see what they are telling you. Lay them out on a paper with the cylinder numbers written down, take a pic and post it up here.
    '98 K3500 7.4Vortec/4L80E, airbags, Bosch injector upgrade, Magnaflow exhaust, custom tuned by me!

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    Re: flashing check engine light

    If they run a scan they will be able to diagnose which cylinder is missing.

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    Registered User ballin_z71's Avatar
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    Re: flashing check engine light

    i bought a scan tool today, cyl 3 missfire. i just did some simple things to narrow down what the problem could be. i swaped spark plugs with cyl1-cyl3, aswell with plug wires.(both plugs looked identical) hopefully its just a bad plug or wire. but this should let me no. all thats left could be the coil/ injector. however i really doubt it being injector. is there anything elese i can do? thnx for help guys

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    Registered User ballin_z71's Avatar
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    Re: flashing check engine light

    finaly got a code again. cyl 1 missfire, thats right a **** wire sent me down a bumby road of trouble shooting. now are my o2s and cats ok???

 

 

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