LeanBurn Conversion or Thrash those Points!

LeanBurn Conversion or Trash those Points!

Heres a relatively easy swap given the daunting view when looking at a leanburn equipped vehicle. At most you may want to trace back the wires from the leanburn system and remove them. But given the fact that Chrysler seems to love taping wiring harnessess, you may not want to trace back to the source.

Mopar Performance does/did market an electronic ignition kit. Visit your dealer for availabilty if you want brand new parts. The kit consists of a distributor w/performance curve and ajustable vacuum advance, ballast resistor, wiring harness, orange ECU, some connectors and an instruction sheet for points conversions.
Mopar also sells the above items separately.

Canadian Mopar Performance part numbers (circa 1993) for the kit;

P3690798 170-198-225 Slant Six
P4529402 3.9 V-6
P3690426 273-318-340-360
P3690427 361-383-400
P3690428 413-426W-440-426Hemi

Your alternate source for the parts is your friendly neighbourhood autowreckers. What you will need to aquire is the distributor (with vacuum advance), ECU, As long a length of the ECU wiring harness as you can get, and ballast resistor. Look for a 4 pin ECU--the 5 pin variety will not work. (all new ECU's are 4 pin). Be sure to look for a donor with a single ballast resistor. Also, keep the attaching hardware, you can reuse it for a factory look installation.
Do NOT simply cut out the wiring harness, trace it back so you can remove the two wires running to the distributor connector.
A word on ECU boxes, they are color coded per level of performance. Blue, Orange, Chrome, and Gold. Be warned, aftermarket plain jane replacement boxes are typically chrome or black. If they don't have the Mopar logo, they are aftermarket low performance replacements.
Note, the chrome and gold (not recommend for the street) boxes are race units. Note two, the blue box is not the base box, but common enough to be found. If its not Blue, Orange, Chrome or Gold AND has the Mopar logo, its the base ECU.

To the meat of the swap, heres a basic wiring diagram, note that only two wires will need to be "mated" with existing wiring.

Press for fullsize wiring diagram

Basic Steps Involved

-Remove the leanburn junk.
-Remove distributor cap-leave sparkplug wires attached.
-Crank the engine so your distributor is pointing to a handy reference. #1 fr'instance.
-Replace distributor with new vacuum advance distributor, set rotor as per above.
-Rotate distributor so pickup coil pole piece is lined up directly with the nearest pole on the reluctor.
-Reinstall distributor cap.
-Install the ECU box. Use the stock location, the holes are already in the fender!
-Choose a location for your ballast resistor. Remember, this sucker gets hot, so keep meltables away from it.
-Plug in the ECU connector, and plug in the mating connector to the distributor.
-check the wiring color codes for your vehicle and for the parts you have. These color codes did change, and in some cases the same color coded wire may have been used with a different pin assignment. Following this, all color codes are from my own reference material and may not match. With reference to the above diagram, the alternate color code for pin 1 has been used on pin 3 in the five wire harness.

The Wiring.

-If your wiring harness has a wire corresponding to pin 3 of the ECU, tape it up or remove it.
-Remove the original wire running to the coils negative terminal.
-Run the black/yellow wire (pin 2) to the coil negative. Crimp or solder on an appropriate connector.
-Remove the orginal wire from the coils positive terminal.
-Take a new wire (supply your own) and run it from the coil positive to the area of the ballast resistor.
-Take another length of your own wire, brown if you want to be factory correct. Connect the above wire to this wire. Crimp or solder on an appropriate connector for one end of the ballast resistor. This brown wire will be connected to a 12 volt source during 'start' only.
-Run the blue/yellow wire (pin 1) to the ballast resistor.
-Take another length of your own wire, blue, and attach this to the above blue/yellow wire and crimp/solder an appropriate connector and attach to the other end of the ballast resistor. This blue wire supplies 12 volts while the vehicle is in the 'run' posistion.

This leaves us with connecting to the vehicles supply for run and start 12 volt sources.
In most cases, you can find the the 12 volt Run wire within the lean burn connector (Pin 2 in my diagram, 14 guage dark blue wire). And, utilize the starter relay. The starter relay has a terminal for Ballast Resistor (12 volt start, brown--not be confused with the other brown wire that goes to the starter solenoid.) The relay terminal layout for the starter relay can be found in just about any manual.

Testing Things Before Firing Up

-Disconnect the brown wire from the starter relay that goes to the starter. Disables starter, but allows starter relay to operate.
-Using a voltmeter, attach a lead to the brown wire at the ballast resistor.
-Turn the key to the "start" posistion, starter relay should click, and you should be see approx. battery voltage.
-Release the key to the "run" posistion, starter relay disables with a click, and you should see approx. 8-9 volts at the ballast resistor.
-If you don't hear the starter relay disable, check your wiring.
-If this checks out O.K., re-connect the starter relay wire and start the car!
-Set timing, test drive, and fine tune.

A Note on Vacuum Advance

The distributor should recieve ported vacuum. If your lean burn carburetor does not have a ported source, there is a vacuum solenoid in place, this coupled with a throttle switch controls vacuum, giving a ported vacuum source. This solenoid is typically found on the passenger side of the vehicle, attached to the diagnal brace in that region.

-Be certain to seal any remaining wires you've cut away and tape them out of harms way.
-If you want the quick route, some silicone will seal the leanburn connectors.
-Double check your wiring before applying the electrons.
-The leanburn carb will allow the vehicle to run, some like crap, some reasonably well. Expect to do some carb tuning. Better yet, replace it.
-On some leanburn systems there is a single ballast resistor utilized, which will have some of the necessary wiring already complete. Check the wiring diagram for your car to verify.

Remember to employ all safety precautions when working on any vehicle.
This information is only intended as an overview and may not include all the necessary information, data, or facts to complete the swap.
Remember, every vehicle is unique, and research for your particular vehicle is recomended.

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