Typical No Spark, No fuel thread here. Just looking for some final input before I go wasting money on random components.

Car:
1996 Eagle Talon Esi with stock 420A, no modifications, 5 spd.

Rundown of failure:
Was hard to start on occasion, with 20 seconds of cranking and then finally started. Did this for a few months, and then one morning stopped working completely. Have been testing random items since. For a brief period it worked again (without me changing anything) but the next day on a hard 1-2 shift it died and hasn't worked since.

Cranks fine, no start. No fire on any cylinder. Plugs not wet after cranking. Pressure in fuel rail.

Items replaced:
None

Tests performed:
-Check engine light: No codes stored, nothing found. Lights up for a few seconds when key is first turned to ON, then goes out, as it should.

-Spark Plug removed: tested for spark while cranking and held to ground, no spark found.

-ASD and fuel pump relays: Both click when ignition turned on. No further testing has been performed.

-Camshaft Position Sensor: pulls 9V and a cycling .2 to 5.0V, both tested at the PCM. I have removed and cleaned the connector and sensor. Is there a magnet on the 420A? (I'm reading about magnets missing in some of my searches)

-Crankshaft Position Sensor: pulls 9V and a solid 5.0V, both tested at the PCM. My DVOM doesn't sample fast enough to pick up the cycle on the CPS (I'm assuming), which is why I'm not seeing the 5.0V jumping up and down. Anyone care to comment on this logic? I have removed and cleaned the connector and sensor.

-Ignition Coil: Did bench ohm test, passed. Has 12V on the middle black/red wire for 2 seconds when key is on, and no voltage on the other two wires. When cranking, it then pulses 12V to zero on all three wires (might be some inaccuracies due to my voltmeter here). Coil has small crack in the bottom brown glue type housing portion that holds the two coils into the black casing (not sure if this would matter).

-Injectors: Hooked up stethoscope and cannot hear them pulsing during cranking. Have not checked with a noid light yet.

-Battery: Both terminals cleaned and solid grounds on chassis and transmission.


Any other suggestions? My main logic is leading towards the coil, seeing that the coil has the 12 V signal, but is not sparking, however I can't get over the fact that the injectors are not pulsing also. Is there any specific sensor or situation that would cause both the ignition coil and the injectors to not pulse? If the ignition coil fails, do the injectors stop pulsing automatically? It just seems strange to have two failures at the same time.

Specific questions:
-What voltages should I be seeing on the coil during cranking?
-What voltages should I be seeing on the crankshaft position sensor when cranking (to confirm other threads)?


I'm obtaining a Fluke DVOM that is very fast and has true RMS capability over the weekend so I should be able to obtain more accurate readings. I will also go pick up a noid light.

Thanks for any input.

Glad to see someone who takes the time to diagnose prior to throwing parts at it.

First thing that catches my attention is the long cranking before spark - this is indicative of a bad camshaft position sensor. I see that you tested it though. If you remove the sensor (2 bolts) there is a magnet attached to the back of the exhaust cam via a torx head bolt. There is no place for it to go however and is unlikely to have gone bad, but check for its presence (especially if you were handed this problem from someone else).

Regarding the ignition coil: a crack in the potting material on the bottom should cause any issues. YOu have a solid +12 on the center wire which feeds both coils. Pin 1 & 3 are the ground signals from the ECU. The ECU will ground those two pins accordingly as it sees signals from the camshaft position sensor. A test you can do to see if the ECU is triggering the coil is check for oscillating ground signals at pins 1 & 3 on the harness side while cranking the motor. If there is no ground signal present, then the ECU is not seeing what it needs to fire the coil.

The coil and injectors all receive power from the ASD relay. During normal operation, upon key on the ECU turns the ASD relay on for 2 seconds. If the motor does not go into cranking status in those 2 seconds, it will turn off. As soon as you turn the key to cranking the ASD and fuel pump relays will instantly power on however.

Regarding your questions:

Crank Sensor
Pin 1 (yellow): +8 volt feed from ECU
Pin 2 (black/green): Ground
Pin 3 (blue/white): Signal Out (should be oscillating signal)

Coil
Pin 1: oscillating ground signal for cylinders 2 & 3
Pin 2: +12 volt feed (normal to have power for first 2 seconds, and turned off if the ECU sees motor is not cranking)
Pin 3: oscillating ground signal for cylinders 1 & 4

My suggestions:
Remove the Crank and Cam position sensors and visually inspect them as best as possible. The Crank and Cam sensors receive their power and grounds from the same source at the ECU. If you are inclined, download the electrical manual at http://www.nawdu.de/files/ to back trace wires. Try and locate a used/known functioning Cam and Crank sensors to swap in. From what you have provided it sounds like a sensor issue.

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2012 2500HD LML

On the signal out for the CPS, to pin 32 on PCM plug #1, I'm getting a solid 5.014 V on my new Fluke DVOM. It does not osscilate.

My Cam sensor signal wire oscillates from 0.904 V to 5.014 V.


Based on this info i swapped the CPS and the car fired right up. Thanks for the input!

No problem, glad you were able to diagnose the problem without wasting needless money on random part replacements. Also, which Fluke did you buy? I have been using an old WaveTek DMM that I bought back in the 90s. I would love to spend a few hundred dollars on a high end DMM

All members should take note of his methods and logical approach to solving the problem. Doing the legwork and providing hard facts when asking for help will yield much more assistance than posting a thread saying "uhh my car won't run right. Help me!"

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2012 2500HD LML