Crank no start

Disconnecting the battery never solves anything, and it erases any diagnostic fault codes, so that valuable information was lost, if there were any codes.

this guide will help us

https://www.2carpros.com/articles/car-cranks-but-wont-start

"Crank" and "turn over" are the same thing. By the parts you replaced, I can assume it cranks okay. What you need to do now is determine if the automatic shutdown, (ASD) relay is turning on. Find the wire that is the same color at the coil pack and at every injector. That typically is a dark green / orange wire, and back-probe that any place. You can use a digital voltmeter, but they often do not respond fast enough, so a test light works better. You will see twelve volts on that wire for one second when you turn on the ignition switch. What is important is if that voltage comes back during cranking. If it does not, the signal is missing from the camshaft position sensor or the crankshaft position sensor.

Very often a fault code for either the cam or crank sensor signal will only set while the stalled engine is coasting to a stop. Once erased, it may not set again during cranking. Then you need to use a scanner to view live data to see if either signal is missing. I use a Chrysler DRB3 scanner. That lists each sensor with a "No" or "Present". I do not know what that would look like on other scanners, but I am pretty sure they have a way to show the same information.

Hi Sprocit. Welcome to the forum. When are you measuring the voltage on the coil? It should only have battery voltage for one second after turning on the ignition switch, then it will come back during engine rotation, (cranking or running).

Caradiodoc

So you DO have voltage to the coil. Do you have spark? If you do, but still have a no-start, have you checked for fuel pressure?

Caradiodoc

If we're assuming the fuel pump and injectors are working, that means the camshaft and crankshaft position sensors are working and the automatic shutdown relay is turning on. If you have no spark, the likely suspects are the coil or the driver circuit in the Engine Computer. By the way, is this a single overhead cam engine?

Caradiodoc

You did not mention anything about the Crank Position Sensor and from symptom description, that should be the component you should concentrate on to get the ignition coil signal. Btw was the ignition coil tested or substituted?

The coil and injector drivers are switching transistors inside the Engine Computer.

Is this a single or double overhead cam engine?

Caradiodoc

When the PCM is powered by the ignition switch, it would ground the ASD relay via connector C3 terminal # 2 (Dark Blue/Yellow wire). Check for continuity between the PCM and ASD relay for the wire.

I should clarify, ... The drivers are transistor circuits inside the Engine Computer. They aren't something you can replace or test. You found the 12 volt supply to the coils. The other end of each coil is grounded by the driver transistors. Current flows through those turned-on transistors and a magnetic field builds up slowly in the coil primaries. At the proper time, the transistors turn off and current flow has to stop instantly. That forces a rapid, sudden collapse of the magnetic field which induces the high voltage spark. If you are finding 0 volts on a coil wire, that circuit is likely working. The voltage only pops up to 12 volts for a few milliseconds. That's much too short to picked up by a voltmeter. If you find 12 volts on the coil wire constantly, that circuit is never turning on. The most likely cause would typically be the Engine Computer but it would be smart to measure the voltage on that wire at the computer's connector in case there is simply a break in that wire. A break in the wire will leave you with 12 volts on the coil wire.

The reason I asked about the engine is the symptoms you originally described match what happened to me on a single cam engine. When the timing belt jumps one tooth, the Check Engine light will turn on. When it jumps three teeth, the valves will hit the pistons causing major damage, but the computer will shut the engine down before that happens. If the belt jumps two teeth, that's when the computer stops the engine but you will often find one coil still firing intermittently.

A hard-to-find problem is a sheared off dowel pin between the camshaft and its sprocket. The sprocket turns a little on the cam mimicking a jumped timing belt. I never heard of that happening on the twin cam engine. Without doing other tests, it does sound like the Engine Computer needs to be replaced.

Caradiodoc

Sorry for the typo, it should be C3 # 3. Do you have continuity between the PCM and ASD relay ( E2 of relay to C3 #3 of PCM)?

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