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Ignition Coil Diagnosis!!

Discussion in 'Ram Trucks' started by DAFFMOBILEWASH, Mar 6, 2008.

  1. DAFFMOBILEWASH

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,598

    Have a no issue with the w350. Started her up without a hitch then the truck stalled out. Checked for fuel pressure OK, seems to have no spark. Pulled the coil wire off and tuned over the engine no arcing. Started to check the wiring to the coil, seems to have power (+)when turing over on the grn/orang wire but noting off the grey. No ground or power. Is this for the output side of things for a tack ??

    Was thinking just to go out and replace the coil but hate to through parts at things as a hunch.

    DAFF
     
  2. RODHALL

    RODHALL Senior Member
    Messages: 374

    is it on the
    1993 DODGE W350 4x4 360 gasser 7.5'ARTIC

    coil would be the cheepest to replace to start with


    BUT i would bet it is the crank sensor.

    magnum motor- take a volt ohm meter. take the tracer wire on any injector, (normaly a green with red tracer) probe it, as it cranks. 1 it gets voltage, CPS is fine, injectors are opening and closing as they should. 2 no voltage - The PCM got no signal from the CPS, so it tripped the ASD (auto shut down), you have no fire and no fuel, replace the CPS reset the PCM and it should start without any issues


    Chris
     
  3. DAFFMOBILEWASH

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,598

    If the CPS was bad would I have 12volts at the coil as the engine turns over??
     
  4. Spitz

    Spitz Senior Member
    Messages: 192

    I would start by disconnecting the coil connector and placing a test light into the the connector so it makes a loop from one terminal to the other and then crank the engine.. The test light should flash with the engine cranking indicating the coil is being powered up by a 12v source and being ground and ungrounded when the pcm wants the coil to fire. If it doesnt flash then you need to check for the 12v source (you say this is present).. This would be the first step in a no spark, power to coil test.. If im not mistaken the coil and all injectors share the common power source.. Hard to keep track of 100's of different cars worked on since i last seen this vehicle type.


    Ok, so i read your post a little closer and you do not have the pcm grounding your coil.. Could be an issue with your crank position sensor..
     
    Last edited: Mar 6, 2008
  5. DAFFMOBILEWASH

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,598

    Replaced the coil, ran for an hour and died out. removed the distributor and replace cap wires rotor and cam sensor. Still no start, figured it must be the CPS. but how to R&R this. It is tucked sooo far back under the firewall I can hardly see it. What is the trick.

    DAFF
     
  6. Spitz

    Spitz Senior Member
    Messages: 192

    Are my posts invisible? Yes, 12v will be constant at the green and orange wire at the coil and at each of the injectors. The pcm controls these with a pulsed ground to each of them. You need to check for that pulsed ground while cranking, if not, its not the coil plugs, wire cap or rotor, but...... you already figured that out....
     
  7. DAFFMOBILEWASH

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,598

    Yes I checked for the 12v power and pulsed ground was there at the time. This was just before I change the coil. While I had the truck in the shop I decide to change the other stuff because the cap looked like an ash tray in the inside and the cam sensor was cheap insurance to rectify any other issues in the future plus I hadn't ever had the cap off. The problem seemed to be intermittent while getting worse with each failure. Now the pulsed ground is missing while cranking!!! This still doesn't help me in the trick of removing the CPS, as far as I can tell I need to remove the PCM and the tubing cap/wirs and grow a second and third elbows and have x ray vision so I can see what I am doing.

    DAFF
     
  8. Spitz

    Spitz Senior Member
    Messages: 192

    Im not sure exactly where this crank sensor is.. Im assuming this one is on the back of the passenger side head and sticks through the bell housing?? If so its a lot easier than it looks...
     
  9. mpflood

    mpflood Member
    Messages: 47

    Same exect problem and symptoms here tonight
    i hear fuel pump
    i have pulse at injector
    spark at coil was there,but not strong looking
    cap and rotor check have to wait till morning(laid out,face down,indented fore head,jesus pose)
    oh yeah, and the plugs wires and metal sleeves are stuck good and probably break when
    tomorrow comes

    Good luck
     
  10. DAFFMOBILEWASH

    DAFFMOBILEWASH PlowSite.com Addict
    Messages: 1,598

    Lower the trans, remove the EGR and tubing, break all the bolts. Remove the exhaust manifold break more bolts R&R sensor and replace all the other stuff. Job wouldn't be as bad if the bolts would come off in one piece. Runs like new now!!!!

    DAFF
     
  11. mpflood

    mpflood Member
    Messages: 47

    Here i go thinking again,did you have a engine code for a ad egr valve or no?