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Discussion Starter · #1 ·
I'm out of ideas. I replaced the dristributor recently (along with cap, rotor & wires) which involved pulling the intake. All went back together and started 1/2 a turn as the truck has always started for the 10 years I've owned it. Drove it, started several times that day with no trouble at all. I was satisifed that the timing should be very close to where I pulled the old distr. First really cold morning, just cranks without even trying to start...wtf? Checked the 1 year old coil and seems it had to low of resistance while cold so I warmed it up in the shop and tried again a few hours later...no luck, no codes, no blown fuses, ASD relay is okay, battery is fine, fuel pressure seems okay, everything seems connected okay. This one has got me stumped so far. Going to change the coil anyway but I'm doubtful it will help. It's like something just shut off everything which is why I checked the ASD...any thoughts would be appreciated!
 

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Discussion Starter · #2 ·
okay...there's no spark. New coil has no spark so the trail ends at the PCM. Without a DRB tool, I'm SOL. I'll go over all of the connections and grounding but I'm sure nothing could have come loose. The cold is likely not a factor as the temp rose above freezing yesterday and it still wouldn't start. All thoughts on this are welcome!
 

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A lotta "seems to be" here. How did you test the ASD? What are your fuel pressure readings? And why would you pull the intake manifold to replace the distributor?
 

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Discussion Starter · #4 ·
Well, I pulled the intake to make sure I marked the dist position properly and gain easy access. I've pulled the intake before so no big deal really. Being an industrial controls guy, testing relays isn't hard to do. I bench tested it and could also feel it change state with the ign key on. Doesn't mean the signal got through but the relay is monitored and should generate an error code if faulty. Don't know the fuel pressure as I didn't want to pay $200 for a proper guage. The rails are under pressure and the fuel pump sounds to be operating okay so I'm focusing on spark. Checked all of the connections and all seems fine. Still no spark. Any idea what signals the PCM is looking for to fire the ign coil? Sure seems like something has become disconnected all of sudden!
 

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Discussion Starter · #5 ·
definately electrical...but where? I was looking at the coolant temperature sensor behind the alternator, removed the connector to examine it. It does not seem like a snug connection and the sensor although tight in the intake seems too flexible as far as the plastic goes. reconnected and the engine started, ran for a minute then stopped without an error code or any other obvious sign. Could not restart but cranks fine. could this be a problem? If the sensor was disconnected, any idea what the PCM would see? I assume the sensor is a resistive type similar to a thermocouple so I'm wondering what range the value needs to be in for permission to start is granted?
 

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Discussion Starter · #6 ·
problem solved but what a pain! Connect ODBPRO, not much info to help diagnose as RPM cannot be monitored through ODB software. Manual tests indicated the CKP and CPS seems fine but I suspected CKP was the culprit even though the problem was intermittent so I bought a new sensor. Installed it and it started right away. Then when engine warmed up, a ticking noise started and it began to run rough until it stalled. This repeated serveral times and then caused error codes 0340 & 1391. I pulled the sensor and it was getting hit on the side by the flywheel only when the engine warmed up...wierd! I checked the angle of the sensor against the original and figured it was out of spec slightly so I bent it (away from the flywheel). Problem solved. The grommet is missing which I though was contributing but doesn't seem to matter. Hope this post helps someone else. :)
 

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Discussion Starter · #7 ·
stumped

spoke too soon...problem not solved!
New crank sensor seemd to fix the problem as it started consistantly and ran fine until Saturday. I pulled it on to the street and let it run while I cleared the snow from the driveway. 20 minutes later it stalled. It will not even try to start. Since the new CKP sensor got swiped by the flywheel, I figured it failed. Ran out and picked up another and installed...no luck. Fuel pressure is good at 48+, new cam sensor, new coil, new wires, cap & rotor. no codes and the ODB software shows RPMs while cranking so what else can I possibly check?
 

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Discussion Starter · #9 ·
Didn't see any voltage at the coil while turning over but I did see spark through a sparkplug. Pulled them all and they're all wet and look a bit fouled so I replaced them, cleaned up any grounds that looked cruddy from the PCM to various splice points and it still wouldn't start. I was about to give up for the time being but was suspicious of the brand new coil from Napa...yep it's crap. Put the 2 year old coil back on and it fired right up. The secondary on the coil tested too low at 7.8kohms. It should be closer to 13k. New part was part of the cause...go figure!
 
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