78 Malibu Fast Start Ignition System

Have you ever wondered why your Turbo Regal cranks for a long time and at other times it cranks right up instantly? This is caused by the design of the ignition system. Below is a description of how the two systems are able to determine how fast the engine starts.

1. Provides faster start-ups within 1/3rd of a crank revolution

2. Eliminates longer cranking times

3. Helps eliminate starter wear and tear

4. Provides engine start-up if the cam sensor should ever fail

5. Uses late model sensors and modules that are still available from GM.

What's the difference between the "Fast Start" and the "Slow Start" ignition systems?

The "Slow Start" units like the ones used on the 84-87 Turbo Regal uses a three wire crank sensor and 1 interrupter ring (on the harmonic balancer) to provide the module and ECM a 3x reference signal. It also relies on a camshaft sensor to provide a reference signal so the module can identify the correct ignition coil to fire when it's on the compression stroke. When the engine is cranking over for start-up the module starts receiving a reference signal from the crankshaft sensor, but won't fire the coil until it receives a camshaft signal. Without a cam signal the module doesn't know which coil to fire. Once the module receives a camshaft signal it will immediately start firing the coils in proper sequence. In actual operation the cam sensor informs the module when cylinder #1 is 25* after top dead center. When the module receives the next reference signal from the crank sensor it will fire the coil for cylinders 6 & 3 and so on. Depending on crankshaft position when the engine was shut off, the engine may have to make two revolutions before the "slow start" ignition system will begin delivering spark. If the camshaft sensor fails the engine will not start however it will continue to run if it looses it's signal while the engine is running.

The picture below shows a running 87 turbocharged 3.8L.

The Fast Start system on the 1988 and later engine is an enhanced ignition system. It uses a four wire crank sensor and 2 interrupter rings (on the harmonic balancer) to provide the module with a 3x and a 18x crank sensor signal.

On the Fast Start system the module provides spark within 1/3rd of a crank revolution. The module can do this because of smarter electronics, along with an additional 18x crank sensor input. Fuel injector operation during start up is also altered. When the computer receives its first tachometer signal, it pulses all six injectors at the same time. This is a primer pulse. Since there is spark and injector pulse with in a 1/3rd of an engine revolution, the engine starts faster, hence the name "Fast Start". Once the computer receives a cam sensor signal it begins sequential fuel injection.

The Fast Start system still uses a cam sensor just like the "Slow Start" but the sensor is used differently. On a "Slow Start" system the engine won't start without a cam sensor signal; a Fast Start system will. In fact, the fast start system operates on the crank sensor alone; the cam sensor signal is only used by the computer for sequential fuel injection.

The ignition module sends three signals to the ECM. It sends a cam sensor signal, a 3x reference signal and a 18x signal to the computer. The 18x signal comes from the 18x sensor and the cam signal comes from the cam sensor, but the 3x reference signal doesn't come from the 3x sensor as you might expect. The module uses the 18x sensor signal and divides it by 6 to produce a 3x reference signal and then sends it to the ECM. This is the reason the late model "Fast Start" ignition system can be used on an earlier ECM like the Turbo Regal; it's this signal that the ECM understands.

The picture below shows a running 1995 Buick LeSabre 3800.

Here's a few general pictures of the "fast start" interrupter rings and how they are arranged. Compare these pictures to the ones above to better interpret how they operate together.

Step 4:

Mount interrupter rings.

Place the two rings on the balancer with the alignment marks lined up with the keyway on the balancer. Clamp them in place with two "C" clamps.

IMPORTANT: DO NOT ALLOW THE RINGS TO MOVE ONCE THEY ARE ALIGNED AND CLAMPED!

Facing the front of the balancer, mark all of the mounting holes using a scribe. Insert the scribe into the balancers bolt holes and scratch a circle on the rings.

After you've marked the holes to be drilled, remove the rings and bolt the two rings together using two bolts and a nuts so they will not move. This will allow you to keep them aligned when drilling the 6 mounting holes.

IMPORTANT: MAKE SURE THEY STAY ALIGNED!

Use a 8mm or a 5/16 drill bit to drill all 6 holes that you marked making sure the rings stay aligned... I can not stress this enough!

After drilling the 6 holes, install the rings on the balancer. You now have the option to use 2, 3 or 6 bolts that also double as studs. I chose to use only 2. These bolts also double as mounting studs for the serpentine belt pulley.

IMPORTANT: If you drilled only 2 holes like me (see picture) make sure the 4 original bolts do not poke out and bend the interrupter rings when tightening the pulley to the balancer. I had to shorten those 4 bolts about 2 or 3 threads. You will not have to do this if you drilled all 6 holes.

Bolt assembly together and check alignment of balancer keyway to interrupter rings alignment marks. Make sure they are still properly aligned.

Rear wheel drive balancer with front wheel drive interrupter rings installed. These two bolts will be replaced with longer bolts upon final assembly.

DISCLAIMER: Bruce and "others" and their methods of designing custom parts in this system may be different than mine but the overall outcome is the same. Custom designing is just that...CUSTOM. Your design may be different than the one I provided on this page. I provided information on what I seen while I was making the switch. If you attempt this, be aware of the "trial and errors" you may encounter when doing such custom projects. As always, I am not responsible if you screw up.