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Check engine light "blinking"

Discussion in 'Chevy Trucks' started by mkwl, Oct 21, 2008.

  1. mkwl

    mkwl 2000 Club Member
    Messages: 2,361

    When I was driving back to school yesterday (2 hr drive on highway)- (truck in my signature), I noticed that my amber "check engine light"- symbol that looks like an engine, flashed once, then about 20 miles later, flashed another 4 times, then shut off and hasn't come on again, yet. Any ideas what might be causing this- is it safe to assume than nothing is really "wrong" since it's not on steady?

    Thanks,
    Matt
     
  2. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,037

    I had that happen to me around 4th of july. I have the 03 gmc 2500HD 6.0 Ext cab long bed SLE. I will be interested to see what gets posted.
     
  3. mkwl

    mkwl 2000 Club Member
    Messages: 2,361

    I just took the truck out again- 4x4 and all seems to be fine- truck didn't have any obvious issues that I could notice- light is not on now. We shall see...Hopefully it never come son again and it was just a flukey thing
     
  4. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    A flashing CE light is the PCM detecting a mis-fire condition on one or more cylinders. Need to do some diagnosis as to which ones and why they're mis-firing.

    Worn plugs
    Defective plug wire(s)
    Dirty/weak/failing injectors
    Or a failing coil pack can all lead to cyl mis-fire conditions.
     
  5. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,037

    BB would a Mass or MAP sensor give a false positive on that? The dealer replaced mine shortly there after it happening. It wasn't to the point of dying out or anything, but you could feel a small hesitation at a stop light.
     
  6. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    It will if it creates a mis-fire due to an extremely lean air/fuel ratio condition from the faulty MAF or MAP. Would definitely explain a hesitation on take off. :nod:
     
  7. mkwl

    mkwl 2000 Club Member
    Messages: 2,361

    Thanks B&B- now, the truck hasn't done it in about 100 miles or so- only flashed 4 and hasn't since. Is it possible that there was some "crud" in the fuel that caused it to misfire, but it resolved itself? Truck seems to be running fine- no hesitation. I don't know if it matters, but I just had the fuel filter changed at my local GMC dealer 2 weeks ago. Do you think it would be good measure to run a little injector cleaner through it (like the STP stuff), and keep an eye on it and see what happens? I can't really see taking it into GMC again, since the light's not on and the truck seems to be fine- is this a fair idea?
     
  8. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Sure it's possible some kind of contaminate in the fuel caused it. If your going to use fuel injector cleaner, use a cleaner called "Sea Foam". Can be purchased at most auto parts stores. Works better than anything I've ever used (including GM's own designated FI cleaner).

    You should at the very least pull the codes on it to see if it stored any..just for future reference if it happens again.
     
  9. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,037

    Good to know. Thanks
     
  10. deere615

    deere615 2000 Club Member
    Messages: 2,919

    We use that sea foam stuff in our jetski, didn;t know I could use it for my truck alos. If I do, should I be doing it everytime I fill up or is one time ok
     
  11. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    A can per tank of fuel won't hurt anything, but it sure would be overkill.

    One can at every oil change is enough for preventative maintenance concerns.
     
  12. ABES

    ABES PlowSite.com Addict
    from MN
    Messages: 1,322

    You guys ever run the seafoam through the vacuum line that goes to the brake booster from the intake?
     
  13. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Absolutely ABES.

    It's a very good valve/intake/combustion chamber cleaner when fed directly into the engine. The GM branded cleaner works well when directly ingested also.
     
  14. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    I have done many times it actual run better than before plus it will blow tons of smoke.

    I say sea foam in vacuum line better than put in gas tank I don't notice very much when put in tank.


    Have anyone see price on sea foam now it was $5.99 now it is $8.99
     
  15. sechracer

    sechracer Senior Member
    Messages: 478

    Glad to see I aint the only one on here useing seafoam.... I tend to use alot of it, wether it be in my bikes, truck or mowers.... Stuff works great as a spray too.... great for rusted bolts...
     
  16. deere615

    deere615 2000 Club Member
    Messages: 2,919

    Ok, I wasn't going to use a whole can, butevery oil change was what I was looking for thanks! sorry for the hijack