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Could it be the Spark Plugs?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by MudFrog, Nov 30, 2000.

  1. MudFrog

    MudFrog 1/2 ton status

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    Ok I got a couple questions for you guys. Last Saturday I replaced my spark plugs because I was getting the same vibration Panther was. My engine had also been running a little rough, so I figured what the heck, aint gonna hurt nothing. Well I replaced the plugs with Autolite Platinum Pro's. First question is what is the correct gap for my 89 blazer with TBI? The manual I have (Haynes I think) said the gap for my 350 is .035, but my dad said he could of swore the TBI's have a wider gap. Also the gap of the plugs that were in the engine were .045. So I wen't ahead and put them at .035 since that is what the book said to do. And I know the gap can increase in time...the plugs I took out were in pretty bad shape. So anyway, I replace the plugs and my engine is running awesome. Not in anyway rough,, and I didn't have the vibration anymore. Well about a day later the engine starts to run rough again and what do you know the vibration is back. Do ya'll think it could be my plugs again? Saturday I'm gonna yank them back out and take a look at them. Can a plug go bad in 1 day? If so what kind of an indication is that about my cylinder?

    89 K5 Silverado
    http://mudfrog.coloradok5.com
     
  2. Emmettology 101

    Emmettology 101 3/4 ton status

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    Pull a plug or two, maybe all of them, and see what they look like. They should have a chocolate look to them, but since they are only a few days old, they should look pretty new.

    Is your check engine light coming on? Do you get any funky smells out of the exhaust(if you still have you cat on).

    I am not a big fan of Autolites, I have never had good luck with them. Always get AC Delcos.


    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; http://emmett.coloradok5.com
     
  3. MudFrog

    MudFrog 1/2 ton status

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    Hey emmetology,
    I do sometimes get the service engine soon light, which I only receive when my engine pings. I usually don't get it a whole lot anymore since I started using 89octane gas. I figured it was just my timing. And yes I do get a awful smell after the service engine soon light comes on. My dad sells the Autolite plugs so I got them for free [​IMG]. I was looking at my old plugs for anything out of the ordinary and I couldn't really tell. Most of them looked normal but I need to compare to the back page of my manual to see if I anything sticks out.

    89 K5 Silverado
    http://mudfrog.coloradok5.com
     
  4. Emmettology 101

    Emmettology 101 3/4 ton status

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    Free always helps! :)

    If your book has a plug guide in it that shows how to read a plug, that is your best bet!

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; http://emmett.coloradok5.com
     
  5. Burt4x4

    Burt4x4 3/4 ton status

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    I had a similar issue and mine felt like I was loosing a cylender. I replaced the plugs and it was better or fixed then it came back so I orderd a set of Summit 8mm spark plug wires and the problem has never returned! So I must have had a bad wire.......

    72K5[​IMG]Led Zeppelin[​IMG]Rock ON![​IMG]
    http://www.burt4x4.coloradok5.com
     
  6. MudFrog

    MudFrog 1/2 ton status

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    Well the good thing is my dad sells spark plug wires too [​IMG]. I guess thats the next thing on my list then. Oh yea... I'm running a High Flow CAT, so I do still have one.

    89 K5 Silverado
    http://mudfrog.coloradok5.com
     
  7. jimmyjack

    jimmyjack 1/2 ton status

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    Its kind of a stretch but I tolerated a vibration for I dunno how long. It turned out to be an intake manifold leak. I changed plugs and wires on a monthly basis it seams. Since I replaced the intake gasket and fixed a few small vacuum leaks my blazer drives like a big fat cadillac. I'm proud of it again! Good luck.

    creepin' and crawlin'

    Jim
     
  8. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Uhhh ping?....your dad sell O2 sensors too? When is the last time yours was replaced? 60k is the replacement time and if it leaned out it would eat the plugs (and pistons) and burn up the converter. Also if the gap is supose to be 45 and you set them 35 your changing the heat range and they may foul out.

    Diging it in the dirt with my K5's
    Grim-Reaper
    http://grimsk5s.coloradok5.com/
     
  9. MudFrog

    MudFrog 1/2 ton status

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    Not sure when the O2 sensor was last replaced or if my dad sells them. I'm not really sure what the gap is supposed to be. The gap on the old ones was .045 and the manual said to use .035 so I used .035 but was kind of hoping one of ya'll would know so I could be sure. Do you think the O2 sensor has something to do with the pinging?

    89 K5 Silverado
    http://mudfrog.coloradok5.com
     
  10. realsquash

    realsquash 1/2 ton status

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    Not likely to the the O2 sensor. You always replace it and see, especially if you're over the 60k limit. You could have set the timing wrong, and that could be doing the pinging and making it runs rough. By the way, when does it run rough? WOT? Idle? Cruise? Hard Cruise?

    When there is pinging, the ECM pulls out up to 15 degrees of timing (i.e. a ton) and that will make your engine run crappy until you let off the gas an allow the ECM to recover (it's called decay) from the ignition retard.

    Squash
    http://www.trailrunners4x4.org/users/realsquash
     
  11. MudFrog

    MudFrog 1/2 ton status

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    Hey Ya'll,
    I just checked my old spark plugs to the back of the manaul, and they look fine.... A little worn but fine. The engine runs rough, obviously on a cold morning, but when I am driving I have a vibration that feels like something RPM related. I thought it was the Tranny at first but now I'm pretty sure it's not. What happens is...
    I'm driving down the road usually coasting because it doesn't take much to get going. From a coast if I want to speed up a little, I will press the gas pedal in a little bit. I will then feel a vibration. If I press the gas down harder it goes away, if I let off the gas it goes away, if I leave the pedal in the same position it will keep vibrating untill the engine RPM's go high enough to make it stop. I can't really tell what the RPM's is cause I don't have a Tach. But the RPM's are pretty low. I could be way off but I would guess 2000 rpm and less. Like I said I have no idea, just trying to give ya'll an idea.
    Now the only thing weird about the pinging is it only happens once. I mean this by if I'm driving down the road and I hear the engine ping and the service engine light comes on, it will not ping anymore untill I turn off the engine and start it up again. Then like usuall sometimes it takes a while sometimes it doesn't ping. Although it usually only pings when I lay into the gas a little.

    89 K5 Silverado
    http://mudfrog.coloradok5.com
     
  12. Thunder

    Thunder 3/4 ton status

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    I have an 89 K5 tbi Here are the specs: plug gap .35 its where I run mine. and my k5 runs great.
    Timing: 0 deg bdc. You must disconnect the black and tan wire on the drivers side of the firewall To properly set timing. The connector looks kind of like a in line fuse holder. If the timing is set without disconnecting this wire it will be way off.
    Autolites are good plugs. I run them in both of my GM vehicles all the time and have no problems.
    Change your plug wires, dist cap, and rotor use GOOD QUALITY parts. This should make your rig run great again.
     

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