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Discussion Starter #1
Hello, and hoping for some assist in solving a continuing problem with my 2002 Dakota four door 2 wheel drive truck with the 4.7 Liter engine. The truck is at 185,000 miles.

The vehicle developed a skip and still has a skip. Miss fire codes indicated the #1 cylinder primary secondary. and Crank sensor.

Here is what has been done thus far:

Removed the plugs and installed new.
Removed the Injectors and cleaned,
Swapped coils around.
Installed crank sensor aftermarket.

Vehicle ran great for 24 hours then started consistent miss fire again.

Power Control Module PCM had always had a checksum error so was sent away,repaired and re programmed.
Did not correct the miss fire.

Replaced cam sensor aftermarket.

Had codes for miss fire on #1, 4, 6, 8 and have ABS wheel sensor code. Until I used torque to clear the codes.

Now have only wheel code and no miss fire codes, but still has miss fire.

Description: The engine starts with no problem initially, as it comes to temperature the miss seems more like a minute interruption in the whole engine electrical. When the rpm is raised, it is very steady, but this blip is on a very regular interval. At ever two seconds for some time and then changes again with same intervals.

Often it will return to idle with no problem, but with each glitch the rpm gets slower and slower until it quits. It restarts with no hesitation.

I have removed grounding wires and cleaned where possible. The battery voltage is a consistent 12 volts.

I have purchased a BAFX OBD2 DONGLE AND INSTALLED TORQUE PRO. for my android tablet.

Is anyone here familiar enough with this app to tell me if it is possible to actually record the spark graph and miss fire count and the injector profile.

Thanks in advance for all assistance.
Professorbob.
 

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Discussion Starter #3
Professorbob

Thanks for the suggestion compression on 345678 was in the 150 psi range and on 1 and 2 about 135. Not enough to cause miss fire I expect.

I just installed 8 new COPs still no change. Runs very smooth from idle through road speed except for the symptom of running out of gas for 1 second on regular spaced intervals. at road speed it is about every 3 seconds to every four seconds.

I do not know if the PCM controls a fuel shutoff relay or not. I don't think there is a problem with the fuel pump because the loss of pressure would cause a longer balk. between events.

I am trying to find the PCM harness plug pin outs and wiring color codes so I can check the individual wiring connection to the crank sensor, the cam sensor and the individual injectors.
The only code now showing is 1381 that has to do with an abs wheel sensor.

VERY frustrating to have such a good truck with 180,000 and not be able to drive it.

Thanks again for your suggestion.
 

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From the wiring diagrams in the FSM:

Crankshaft position sensor: Ground - black/light blue to C1 pin 4 on PCM
5v power - orange to C1 pin 17 on PCM
Signal - gray/black to C1 pin 8

Camshaft position sensor: Ground - black/light blue to C1 pin 4 on PCM
5v power - orange to C1 pin 17 on PCM
Signal - tan/yellow to C1 pin 18 on PCM

Injectors: #1 - Power - dark green/orange from ASD
Driver - white/dark blue to C2 pin 4

#2 - Power - dark green/orange from ASD
Driver - tan to C2 pin 15

#3 - Power - dark green/orange from ASD
Driver - yellow/white to C2 pin 5

#4 - Power - dark green/orange from ASD
Driver - light blue/brown to C2 pin 16

#5 - Power - dark green/orange from ASD
Driver - gray to C2 pin 6

#6 - Power - dark green/orange from ASD
Driver - brown/dark blue to C2 pin 12

#7 - Power - dark green/orange from ASD
Driver - violet to C2 pin 2

#8 - Power - dark green/orange from ASD
Driver - gray/light blue to C2 pin 13

The automatic shutdown relay (ASD) controls power to the injectors, coils, and O2 sensors, and is controlled by the PCM through a dark blue/yellow wire on C3 pin 3.

Connector 1 on PCM is black plastic, Connector 2 is white, Connector 3 is gray
 

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While looking up the wiring information for your engine, I noted a capacitor connected in parallel with the injectors. It's apparently to suppress static noise for the sound system, but is not installed (that I could find) on any of the other engines. I'm not big on electrical theory, but I have always understood that a capacitor (used with breaker point ignition systems) was either good or bad - shorted or doing what it is supposed to. However, upon reading a brief description of capacitors, they are subject to decreased performance when subjected to excessive heat, and breakdown of whatever material used to insulate the capacitor. Just on a hunch, try disconnecting the capacitor and see if it makes any difference when your engine warms up.

I don't have the 4.7, so can only go by what the FSM says about its location. It is supposedly on the right side of the engine compartment, possibly on the fender liner down low, and has a single wire (dark green/orange) going to it. The connector itself is supposed to be black plastic. The only effect disconnecting it would have would be static in your radio. Make sure the wire does not get accidentally grounded - that would short out the circuit.
 

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I have on occasion over the years installed a new spark plug, coil, etc. thinking the problem solved. Then, spending Hours chasing everything back down to the new part. You mentioned the truck ran good for 24 hrs. try checking the crank sensor again.
 

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Discussion Starter #7
1391 intermittant CMP CAM AND CKP CRANK SENSOR SIGNAL

Thanks for all the suggestions, I will try and locate the capacitor. I saw what appears to be one bolted to the wheel well. I will take a look see. I checked the harness sensor end plugs on both the Cam and Crank. I have both new replacement sensors out to run some test. Do you know what the ohms should be on the hall effect circuit.
I am also curious about the shutdown relay. Could it possible be capable of interrupting the injector and coils circuits on a cycle of 1 second with 3 second cycle. The balks sound just like the truck has been switched off for just an instant.
I starts with no problem, except for the balks it has plenty of power and runs

Thanks, Robert
 
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