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Cold blooded

Discussion in 'Ram Trucks' started by pmm, Dec 13, 2008.

  1. pmm

    pmm Junior Member
    Messages: 11

    I have a 1999 Ram 2500 with 5.9 and AT that idles rough after several minutes of running and then it seems to come out of it. It has fresh plugs, wires and air filter. It's getting adequate fuel. A speed sensor was replaced recently.

    Any thoughts?

  2. murphyslaw

    murphyslaw Senior Member
    Messages: 443

    my 2000 is the same way, until its warm enough to lift the gauge off the bottom line it runs like crap.
  3. Joe Snow

    Joe Snow Senior Member
    Messages: 120

    I've got an '05 that idles rough for less than a minute then all is well. That's if it sits outside and it's real cold out. After running for a couple minutes, it's programmed to go into high idle mode which speeds warmup. I think that's a flash available to 3rd generation and newer trucks.

    Do you plug your truck in? That might do away with the rough idle issue.
  4. 89smurf

    89smurf Junior Member
    from Sask.
    Messages: 13

    Sounds like either an IAC or coolant temp sensor problem.
  5. Spitz

    Spitz Senior Member
    Messages: 192

    Did any spark plugs look wierd you took out?? Using any oil??
  6. pmm

    pmm Junior Member
    Messages: 11

    It doesn't use any oil. The truck sits all week and it used very little on the weekends, it has 78K miles on it. The old plugs had never been changed by the origial owner so they were tough to get out . What do you mean by funny? I found an intake manifold bolt head that seaps a very minimal amount of coolant, I don't know if that has any connection to the problem.
  7. Joe Snow

    Joe Snow Senior Member
    Messages: 120

    That's where I misread. I saw 5.9 and immediately thought you were running a Cummins. Disregard my previous post:sleeping:...

  8. Spitz

    Spitz Senior Member
    Messages: 192

    Well the truck runs in open loop untill a few parameters the computer sees are met (open loop= computer does not control fuel, its a preset data log that is used).. After a few minutes its probably going into closed loop, which means the computer is takign in info from such sensors as oxygen sensors and a few others to control what fuel delievery and spark timing are.. It sounds to me like maybe you have a rough running condition in open loop, in closed loop the computer can make corrections in fuel if say, you had a larger vacuum leak.. The computer can add fuel to make up for the added air taken in based on what some sensors tell it.. If you already did a basic tune up its probably wise to take it to a shop if you feel its something that should be looked at.. If your having coolant leak at the intake gaskets, that may be a problem.. If coolant can get out, its very possible you have a vacuum leak as well (air is thinner than water right?) We've found the intake bolt get corroded completely off and actually break, they look fine untill you go to take them out. Just a suggestion however..

    ps- I asked about the oil because on the bottom of the intake itself there is a flat pan that is used, at around 80-100k, from what we've seen, these gaskets suck out from being old and brittle and can cause an internal vacuum leak, they end up using oil and oil fouling the plug where the intake happens to blow out.. This little gasket doesnt seal coolant, its just a pan on the bottom of the intake, they must not be able to cast the intake in any other way, so they have to use this pan.. Thats why i asked about the oil useage.. If you do end up doing the intake gaskets, this should be done as well when the intake is off.
    Last edited: Dec 14, 2008
  9. pmm

    pmm Junior Member
    Messages: 11

    Thanks Spitz.
  10. cmo18

    cmo18 Senior Member
    Messages: 815

    If you need more help, jump over to dodgeforum.com, another awesome site...Spitz are you talking about the plenum gasket?
  11. Spitz

    Spitz Senior Member
    Messages: 192

    I believe they call it the plenum gasket, you cant see it untill you take the intake off tough, its still a vacuum leak, its just pulling air in from the crankcase.. Usually its the back plugs that get oil fouled and may cause a miss. If you were to look down the throttle body, you'd be looking at the pan im talking about.. One way to check for an internal vacuum leak is remove the pcv and block it off and then pinch off the fresh air inlet to the valve cover.. Now with the engine running this should build pressure in the crankcase.. After we start the truck we take off the oil cap and see if its building pressure (good) or if its creating a vacuum (some sort of internal vacuum leak present)..
  12. USMCMP5811

    USMCMP5811 Senior Member
    Messages: 267

    That is one way to test for a blown plenum gasket... The 5.9 magnums are famouse for them. Look down the throttle body, if you see oil, your plennum is blown. replace with a hughes kit or an M1 intake, otherwise, you WILL be doing the gasket again.