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Discussion in 'Trucks and Trailers' started by CLM1, May 3, 2001.

  1. CLM1

    CLM1 LawnSite Member
    Messages: 90

    "98 Quad-cab w/5.9 (360) Spark-knocking. I've tried everything I can think of and has been to the dealer three times for this. Does it with any brand or octane fuel.
    Any suggestions/cures?
  2. thelawnguy

    thelawnguy LawnSite Silver Member
    Messages: 2,411

    Its supposed to ping slightly on hard acceleration-thats the sign of a well-tuned engine.

    Since its been to the dealer I assume the PCM updates have already been done. If so they would have applied a sticker to the controller with the new update number (controller is against firewall passenger side).

    If its pinging excessively even at light throttle, and the dealer has re-flashed the PCM, 1) check the fuel injectors, one defective one will make the PCM think they are all squirting too much fuel and lean out the mix excessively (this means removing them all and flow-checking them) if they pan out 2) check the intake manifold gasket they are known to be weak on the 5.9 causing too lean running due to vacuum leaks.

    See these links for more info:

  3. CLM1

    CLM1 LawnSite Member
    Messages: 90

    Thanks for your reply.
    But....Been there done that.
    Thinking of after market Computer, throttle body spacer and cold air intake.
    Already running K&N filter and 3" duals w/flomasters.
    You woudln't believe how I ended up with this truck. To make a long story short, since I need to get outta here and do some work, I forced Chrysler to purchase my previous truck back from me for this very same reason. It started spark-knocking at 3,000 mi. and they got it back at 58,000. My '98 started at 36,000.
    Have a good day!
  4. thelawnguy

    thelawnguy LawnSite Silver Member
    Messages: 2,411

    Please list what has been done-at least, according to the dealer RO's.

    The aftermarket computer will only make matters worse.

    Is the temp sensor operating properly? Where does the dash gage needle stay? Not only does it feed the dash gage but also feeds input to the computer. Your dash gage should stay around 200, maybe a needle width higher or lower.

    The most common reason for spark knock in the 360 is an injector dumping too much fuel into the engine, causing the computer to (erroneously) lean out the air/fuel mixture of the rest of them causing a lean mixture knock. No code will be stored either.

    Ford Mustang 5.0HO injectors are direct replacement for the Ram, before sending the truck to the crusher I would install a set of 8 from the Ford Performance catalog.
  5. That should be good for at least a 2-3 decrease in mpg.
  6. Barkleymut

    Barkleymut LawnSite Bronze Member
    Messages: 1,117

    To Stone or anyone interested: Why would a more efficient exhaust and more efficient intake (a filter upgrade in this case) cause lower MPG? It seems to me the truck would produce more HP with these and therefore the pedal would be pushed down less and therefore the gas would be used more sparingly. This is based just on logic and as I have found out before my logic is not always 100%. Just looking for a logical explanation to why this is not a more efficient setup. Anyone found ways to increase MPG? Is the K&N I have actually costing me more at the pump?
  7. JV

    JV LawnSite Member
    Messages: 5

    I too have have this knock problem. '99 RAM 2500 4x4. Started about 1,500 mi. 89 or 93 octane helps but who wants to spend the money when the owners manual states the engine is designed for 87 octane (not to mention gas prices). The dealer has cleaned the injectors ($130+)under warranty - helps but not much. Used 2 cans of GM Top Engine Cleaner at once, (shake can first and follow directions - you may have to turn off engine as I wasn't able to stall it out with the TEC), this has been the best fix yet.

    BTW - the dealer said they could "de-tune" the engine, but I would take a hit in fuel economy. I'm already black and blue from the fuel economy - no thanks.

    It's enough to make me look at Chevy again...

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