Hey check your ground to ecu...Here some good reading on the subject.
Chrysler Electronic Ignition
Background
Starting in 1972, Chrysler began using a revolutionary new electronic ignition system. This system replaced the conventional points type distributor with a magnetic pickup coil and electronic control unit (ECU). This system eliminated routine maintenance and replacement of ignition components and provided better timing accuracy, more spark and higher RPM limits.
This new ignition system introduced the electronic control unit (ECU), which was mounted to the firewall or inner fender. The distributor remained basically the same except for the pickup coil that was mounted in place of the points and the reluctor that replaced the rotor. The distributor retained the same housing and vacuum advance system that was used on points type ignition systems.
The theory of operation is very simple. The reluctor is similar to the rotor of a points type system, except it has vertical vanes that protrude from the side. As the distributor turns, these vanes pass very close to the core of the pickup coil. This induces a small electrical pulse into the coil, which is sent to the ECU. The ECU acts as an amplifier for these pulses and in turn sends a much larger pulse to the ignition coil. The coil acts the same way as in a points type system and produces the high voltage needed to fire the spark plugs.
Application
Chrysler's electronic ignition was used on all 1973 and '74 vehicles and on 1975 and newer vehicles that did not use Electronic Lean Burn, or Electronic Spark Control. Because Chrysler engineers chose to make the electronic ignition system a drop-in replacement when it was introduced, it is very easy to adapt it to earlier vehicles or those later vehicles that did not originally use it.
Many owners are faced with having to deal with less than ideal ignition systems, especially those who own mid to late 70's or early 80's V8 powered Chrysler products. Cars of this era were largely equipped with what Chrysler originally called Electronic Lean Burn. It was supposed to be the next great advancement in electronic ignition control. It was a computerized system that took input from various sensors and then used pre-programmed data for delivering precise ignition timing. Unfortunately, it was plagued with over-complexity and the poor choice of attaching the electronics to the side of the air cleaner. This location subjected the control computer to excess heat and vibration, which often led to failure.
Whether you are converting an earlier ignition system, replacing Lean Burn, or repairing an existing electronic ignition system, the work is not at all difficult. Because the electronic ignition system used only a few components, it is easy to work with and troubleshoot. The requirements for installing an electronic ignition system are as follows:
An alternator with an electronic voltage regulator.
Electronic Control Unit (ECU).
Distributor with a pickup coil.
Ballast resistor.
Wiring harness.
Fortunately, Mopar Performance has made it easy to buy most of what you need in a complete kit. Kits are available for the following applications:
Application Mopar Perf.
Part Num. *
170-198-225 Slant Six P3690789
3.9L V6 P4529402
273-318-340-360 Small Block V8 P3690426
361-383-400 B Engines P3690427
413-426W-440 RB and 426 Hemi Engines P3690428
* Source: 1996 Mopar Performance Catalog
If you are working with an existing system or performing your own conversion, many of the individual components are interchangeable. The pick-up coil is common to all applications, while the reluctor is different between 6 and 8 cylinder engines. Each of the applications listed above uses a different distributor. The stock ECU is interchangeable with any application, but Mopar Performance markets several replacement units for high performance applications.
Application Mopar Perf.
Part Num. *
Orange Box for up to 6000 RPM P4120505
Chrome Box for up to 8000 RPM (race) P4120534
Gold Box for up to 10000 RPM (race) P4120600
* Source: 1996 Mopar Performance Catalog
Troubleshooting
Troubleshooting an electronic ignition system is fairly simple. Once it has been determined that there is no spark, there are a few quick checks that can be performed to determine the cause. A DC volt/ohm meter can be used to check the continuity of the pick-up coil. It can be checked at the leads as they leave the distributor, or on pins 4 and 5 of the ECU connector. When measuring the resistance across the two leads of the pick-up coil you should see a 150-900 ohm reading. Always flex the wiring leading to the distributor and to the ECU while checking the resistance to be sure that there are no breaks in the wiring. You should also check for 12 volts at pin 1 of the ECU connector when the ignition is in the "on" position. It is also important that the ECU be securely bolted in place and that bolts provide a good ground to the ECU housing. The only other lead that is connected to the ECU is the "-" lead to the coil, which can be checked to insure that it is not broken.
Chrysler Electronic Ignition
The other important component of the electronic ignition system is the ballast resistor. It should be checked with an ohm meter and should have 1.2 ohms of resistance. Typically, a failure of the ballast resistor will result in the engine starting, but then dying as soon as the key is released from the start position. It is often handy to have a spare ballast resistor or ECU lying around to use for troubleshooting.
1. Engine turns over but will not start:
a. Recheck all connections for being loose or poorly connected. b. Check to see if battery voltage (12 volts) is being supplied to the ballast resistor when the ignition key is held in the start position. If not, clean or repair all the electrical connections from the battery to the ballast resistor, c. Check to ensure that the ECU is grounded. This usually occurs when the ECU is bolted down, but a separate ground wire from the ECU bolt to the body or engine or battery may be required. See page 7, section #6. d. Recheck the Main Ignition Feed splice if one was required. e. Double check the distributor position to be sure that the distributor is NOT installed 180 degrees out of phase - rotor points the wrong way. Check this against the valve position on the #1 cylinder.
2. Engine idles rough and stalls:
a. Check the battery's state of charge. It must be a minimum of 12.5 volts with the engine running. (Minimum specific gravity must be no less than 1.250.) b. The coil output may be low. Have the ignition coil checked for maximum output. It should be at least 20 KV. 40
KV or higher is preferred on a race/performance vehicle, c. Check for carbon tracks in the distributor. d. Check spark plug wires especially if they have not been replaced.
3. High speed miss:
Helpful Suggestions:
a. Check for loose connections or poor grounds. b. Check for dirty or worn spark plugs. c. Check for faulty spark plug wires or poor connections on new wire sets. d. Check the battery voltage at the ballast resistor. It must be no lower than 12.5 volts. This is especially important on cars with alternator cut outs or cars with no alternator. If the vehicle uses an alternator cut out, test the voltage with the alternator turned off.
