1998 ford mustang not getting fire to spark plug.several new parts have been put on. I'm replacing PCM & constant control module(used parts).can I bypass reprogramming? It's getting very costly. Thanks so much

When you turn ignition key on ( not start ) does the checking light ,light ? Check fuse's for PCM , are they good ? Find a wiring diagram an check power an ground at PCM . Also hook up a scan tool an see if it will communicate with the PCM . That's how you check the PCM ! Also check the constant control relay module , these go bad an they have fuel pump relay , power hold relay , this powers up fuel injectors an ignition system !

When you have Coil Packs not firing Spark... it's usually due to one of two reasons: 1.) the Coil Pack is BAD 2.) the Ignition Control Module (ICM) has fried internally and is not activating that specific Ignition Coil within the Coil Pack ...The most common is the ICM ...The probable reason your catalytic conv. gets red hot is due to raw gas being dumped through the exhaust from the no fire on your cyl... Running it like that can cause severe damage to your conv...

Check your Constant Control Relay Module.

If the coil pack did not resolve the issue you are experiencing, then you may either have an injector issue, or a faulty PCM-powerterain control module, also known as the vehicle's computer.

ECM/PCM. Also known as electronic control module/powertrain control module.

You check the right firing order?

1991 Ford Mustang 2.3 liter SOHC L4





1991 Ford Mustang 5.0 liter V-8 HO



Also, need check the PCM for someone short; sometimes this is the reason it wasn't sending a signal to the coil. You have constant power at the coil but the ground signal doesn't fluctuate from on to off while the engine is cranking. If the hall effects switch in the distributor is bad it won't tell the PCM when to fire the coil and the hall effect switch also operates the tachometer. So if this switch is bad the tach and the coil would not work.

Good luck.

Did you check the timing

i have owned many mustangs before and the problem one is your plugs and two is the ignition module

1. Note: Electronic Ignition engine timing is entirely controlled by the PCM. Electronic Ignition engine timing is NOT adjustable. Do not attempt to check base timing. You will receive false readings.
   

The CKP sensor is used to indicate crankshaft position and speed by sensing a missing tooth on a pulse wheel mounted to the crankshaft. The CMP sensor is used by the COP Integrated EI System to identify top dead center of compression of cylinder 1 to synchronize the firing of the individual coils.

1. The PCM uses the CKP signal to calculate a spark target and then fires the coil pack(s) to that target shown in Figure 51. The PCM uses the CMP sensor not shown in Figure 51 on COP Integrated EI Systems to identify top dead center of compression of cylinder 1 to synchronize the firing of the individual coils.

1. The coils and coil packs receive their signal from the PCM to fire at a calculated spark target. Each coil within the pack fires two spark plugs at the same time. The plugs are paired so that as one fires during the compression stroke the other fires during the exhaust stroke. The next time the coil is fired the situation is reversed. The COP system fires only one spark plug per coil and only on the compression stroke.
   
   The PCM acts as an electronic switch to ground in the coil primary circuit. When the switch is closed, battery positive voltage (B+) applied to the coil primary circuit builds a magnetic field around the primary coil. When the switch opens, the power is interrupted and the primary field collapses inducing the high voltage in the secondary coil windings and the spark plug is fired. A kickback voltage spike occurs when the primary field collapses. The PCM uses this voltage spike to generate an Ignition Diagnostic Monitor (IDM) signal. IDM communicates information by pulsewidth modulation in the PCM.

1. The PCM processes the CKP signal and uses it to drive the tachometer as the Clean Tach Out (CTO) signal.
   

2.5L V6

The ignition system consists of an ignition coil, spark plug wires and spark plugs.
The crankshaft position sensor signal is the basis for ignition timing calculations. The alternating voltage signal from the crankshaft position sensor is digitized by a pulse former within the powertrain control module. This digitized signal is then used to position the closing time of the primary circuit of the ignition coil.
Ignition timing is determined by the powertrain control module in response to engine operating conditions based on stored data tables or maps. Once ignition timing has been determined, the powertrain control module interrupts the current to the primary circuit of the ignition coil thus triggering the ignition spark which is supplied to the cylinders through the spark plug wires and spark plugs.
The ignition coils are triggered by the powertrain control module in pairs (cylinders 1 and 5, cylinders 4 and 3 and cylinders 2 and 6) sending one ignition spark to the firing cylinder and one ignition spark to the corresponding cylinder on the exhaust stroke. This ensures that any unburnt fuel residues remaining in the cylinder on the exhaust stroke are re - ignited to provide cleaner exhaust emissions.
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2.0L 4 cynder

The ignition system consists of an ignition coil, spark plug wires and spark plugs.
The crankshaft position sensor signal is the basis for ignition timing calculations. The alternating voltage signal from the crankshaft position sensor is digitized by the powertrain control module. This digitized signal is then used to position the closing time of the primary circuit of the ignition coil.
Ignition angle is determined by the powertrain control module in response to engine operating conditions. Once ignition angle has been determined, the powertrain control module interrupts the current to the primary circuit of the ignition coil thus triggering the ignition spark which is supplied to the cylinders through the spark plug wires and spark plugs.
The ignition coils are triggered by the powertrain control module in pairs (cylinders 1 and 4 and cylinders 3 and 2) sending one ignition spark to the firing cylinder and one ignition spark to the corresponding cylinder on the exhaust stroke. This make sures that any unburnt fuel residues remaining in the cylinder on the exhaust stroke are re - ignited to provide cleaner exhaust emissions.
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Integrated Electronic Ignition System The Integrated Electronic Ignition (EI) System consists of a crankshaft position (CKP) sensor, coil pack(s), connecting wiring, and PCM. The Coil On Plug (COP) Integrated EI System uses a separate coil for each spark plug and each coil is mounted directly onto the plug. The COP Integrated EI System eliminates the need for spark plug wires but does require input from the camshaft position (CMP) sensor.
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The first thing i would do is put a new ignition control module on it. If that doesnt fix it, some of the newer model vehicles have made it so the power control module (pcm or brain) has to be reset everytime you change the battery. I hope that helps you out.