EM-3 F 4 cyl Supplement

Version 3.2 July 20, 2000

System Description

The F4 system is an integrated fuel injection and direct fire ignition system designed for 4 cylinder engines. Engine spark timing is fully programmable for both RPM and/or manifold pressure/throttle position. Programming is done with the standard SDS hand-held programmer.

Triggering is accomplished with magnets attached to the crankshaft pulley and a Hall effect sensor fitted to the timing cover. As such, timing variations relating to belt and chain deflection or gear harmonics are eliminated.

Two, twin discharge GM coils are used.

Applications

The F4 system will work only on 4 cylinder, 4 stroke engines.

Theory of Operation

Two triggering magnets positioned 180 degrees apart are employed plus 1 synch magnet. A double Hall sensor element detects the passage of each magnet and sends the pulses to the ECU. The ECU determines the exact rpm and manifold pressure, sums the programmed Spark retard values and calculates the appropriate delay for the specific conditions at that instant, then triggers the coils to fire at the precise time. The F4 system employs a waste spark strategy where the plugs on two cylinders are fired simultaneously, 1 on compression and 1 on exhaust.

By setting an initial offset value, MAGNET POSITION, the LCD programmer will display the actual ignition timing in degrees BTDC in real time in gauge 2 mode. Programming can then be accomplished in the simplest possible terms to understand.

Mounting the Hall Sensor

The Hall sensor may be mounted anywhere around the outside of the crankshaft pulley that is convenient and does not interfere with accessories such as the alternator or water pump.

The Hall sensor assembly should be positioned so that the sensor element clears the crankshaft pulley face by 2 to 4 mm (.080 - .160). The sensor may be mounted to face either the front or the rear of the pulley depending on where the triggering magnets would be best located and clearance from other interfering items. It is essential to ensure that the Hall assembly bracket and wires do not touch the fan belt, pulleys or hot engine parts.

The square black sensor elements must be placed so that the magnets on the crank pulley spin over their centers with 1 to 2mm ( .040 to .080) clearance. Magnets will protrude about 0.5 to 1.0 mm past the pulley face. Note: on rubber damped harmonic balancers, the minimum Hall to magnet clearance should be 2.0mm to prevent contact due to pulley flex. Magnet contact with the Hall sensor will usually destroy the sensor. Always turn the crank by hand and check clearances before starting the engine.

When aligning the sensor with the magnets, use the blue line on the Hall sensor as the reference mark. This denotes the trigger element. All measurements are referenced from this point. Refer to figure 2.

Be certain to mount the sensor on the side of the pulley which is wide enough and thick enough to contain all 3 magnets. If this is not possible, a different pulley may have to be used or an aluminum disc can be machined and bolted to the pulley to house the magnets.

Usually, another bracket must be fabricated to attach to the timing cover bolts in order that the sensor bracket can be bolted in the proper position. Figure 2 shows a typical installation. The sensor bracket should be initially positioned in the center of its adjustment slot to allow maximum movement in or out for final placement once the magnets are in the pulley. The sensor is supplied with #10-24 Allen bolts. Slot spacing is 28mm (1.1 inches). Use a #25 drill and tap with a 10-24 tap. The sensor must be rigidly mounted on a bracket with no flex. If you can see your bracket flex with hard finger pressure, your mount is not rigid enough. For details on building Hall sensor mounts, refer to our website Tech Page.

Ideally, the Hall sensor should be mounted so that the sensor edges point towards the center of the crankshaft, not at an angle to it.

The wires leading from the sensor should be securely wire- tied every few inches to avoid vibration breakages. Do not route the Hall sensor wires close to the ignition wires or high current devices such as the alternator or starter. The ECU gets its RPM signal from the Hall sensor on the F unit instead of the coil as on the D model.

Mounting the Magnets

Triggering for the SDS ignition system is accomplished with high performance magnets mounted in the crankshaft pulley. These magnets must be precisely positioned both in relation to TDC and each other for proper functioning of the system. Be very careful with these magnets as they chip easily and stick to any ferrous surface so are easy to lose.

The F4 system uses 2 magnets spaced 180 degrees apart for triggering and 1 synch magnet spaced 40 degrees ADVANCED in the direction of crank rotation of the first (1-4) trigger magnet. See figs 1 and 2.

A circle must be scribed on the pulley face using a lathe, calipers or divider. This circle must allow the center of the Hall sensor elements to intersect the line. Magnets will be placed along this circle. Draw an arrow with a marker on the magnet side of the pulley to indicate the direction of pulley rotation. This is very important to avoid confusion later.

Magnets should be positioned as per the following description and figures 1 and 2. In all cases, the crankshaft should be turned until the TDC or 0 mark on the pulley aligns with the pointer, TDC or 0 mark on the timing cover. With the Hall sensor loosely bolted in position, a mark should be made on the pulley where the blue reference mark of the Hall sensor elements intersects the pulley- From this mark, the first magnet (1-4) should be placed 80 degrees ADVANCED in the direction of crankshaft rotation. This is best determined using the paper gauge supplied with your system or a protractor. A line should be marked on the pulley at this position. Now, a centerpunch should be used to mark where the magnet will be placed at the point of intersection of this line and the scribed circle. Make sure that the pulley is thick enough at this location and that centerpunch mark lines up with the circle to coincide with the trigger element (blue line).

Next, the diameter of this scribed circle must be precisely measured using calipers. The diameter of the scribed circle divided by 1.414 will give the dimension of 4 equidistant points along the scribed circle when using calipers or dividers. The original mark and the

mark 180 degrees from it (2-3 magnet) will be where the two magnets are placed. The other two marks can be ignored. See figure 1.

This synch magnet will be mounted about 40 degrees ADVANCED in the direction of rotation ahead of the (1-4) trigger magnet. Use the 40 degree paper template supplied or a protractor to locate this magnet and centerpunch for drilling. If you are unsure of mounting the magnets accurately and properly, have the work performed by a qualified machinist.

Magnets measure 3.5mm long and 3mm in diameter. They are mounted in the crank pulley by drilling holes with a .125(1/8)inch diameter drill bit. This should be done in a drill press, very carefully, until the correct depth is reached. Hole depth should be 2.5 to 3mm (.100 to .120 inch) to allow the magnet to protrude 0.5 to 1.0mm (.020 to .040 inch) above the pulley face. The magnets can be mounted on the front or the back face of the pulley depending on which side is more suitable for magnet and Hall sensor placement. It is important to ensure that there is sufficient material thickness to drill a 3mm deep hole without breaking through and sufficient face width to allow mounting both sets of magnets.

The magnets and drilled holes must be free of oil and chips before gluing the magnets in position with 5 minute epoxy. TRIGGER MAGNETS MUST BE GLUED IN WITH THE WHITE END FACING THE SENSOR.

THE SYNCH MAGNET IS GLUED IN WITH THE WHITE FACE AWAY FROM THE SENSOR.

A slight meniscus of epoxy is desirable around the magnet for best retention, These magnets are usually impossible to remove without destruction of the pulley and magnets so make sure you do this step correctly.

To verify that you have mounted the magnets properly, use the following procedure:

1. Turn the crankshaft to TDC #1.

2. Turn the crankshaft backwards 180 degrees so that it is at BDC.

3. Turn the crankshaft in its normal direction slowly until about 120 degrees before TDC. The synch magnet should be crossing its Hall sensor element at this point.

4. Keep turning the crank to about 80 degrees before TDC. The #1 trigger magnet should be crossing the trigger element (blue line) on the Hall sensor at this point.

5. Keep turning the crank to be sure that the #2 trigger magnet crosses the trigger element at a 180 degree interval before the synch magnet comes by again.

Aligning the Hall Sensor

Exact alignment of the Hall sensor elements with the magnets is critical for proper operation of the system. Proper alignment can be confirmed by calling up the magnet alignment mode in the programmer window.

F systems have a window to the right of gauge mode- The window is available by pressing the > button while in gauge 2 mode- The LCD Screen will read MAGNET SEEN or MAG NOT SEEN and SYNCH MAG SEEN or NOT SEEN. As a magnet passes the Hall sensor, the graphic will change from NOT SEEN to SEEN.

Reposition the sensor slightly until the SEEN graphic is displayed with the magnet lined up. Tighten the sensor bolts. Recheck by turning the crankshaft by hand, As each magnet passes the sensor, the display should change to SEEN momentarily. The magnet should be SEEN for at least 2 or 3 degrees of crank rotation. If not, try to realign the sensor.

Make sure that there is at least 1mm clearance between the magnets and the Hall sensor (2.0mm on rubber damped pulleys) before starting the engine. Never attempt to start the engine until this step has been performed.

Note: This window is only valid when the crank is turned by hand because the sampling rate of the programmer is too low to display this parameter with the engine running.

Initial Setup - VERY IMPORTANT

This involves calling up the MAGNET POSITION parameter. This step should be performed as soon as the engine is fired up and idling. Ignition timing is meaningless without first setting the MAGNET POSITION parameter properly. Note that MAGNET POSITION and RPM IGN are totally separate parameters.

A value of between 70 and 90 entered should allow the engine to be started. 80 would be a good starting point and is where the system is factory set.

STEP 1. Go to RPM IGNITION 1000 and set that value to 10. Also set RPM IGNITION 1250 and RPM IGNITION 1500 to a value of 10.

STEP 2. Make sure that all IGN RET/MANPRESS values below boost are 0.

STEP 3. Start the engine and keep it running below 1500 rpm.

STEP 4. Connect a timing light.

STEP 5. Change the MAGNET POSITION value until the timing light reads 10 degrees BTDC.

NOTE: ADVANCE OR DIGITAL DELAY TIMING LIGHTS WILL NOT READ PROPERLY DUE TO THE WASTE SPARK, SO IT IS BEST TO USE A REGULAR INDUCTIVE LIGHT.

Once the MAGNET POSITION is set, it does not have to be changed again- it is only to tell the ECU what the "distance" between the 1-4 MAGNET and TDC is. Once the above 5 steps are completed, you may enter your desired timing curve.

Ignition Programming

Ignition timing requirements differ widely between various types of engines so we can only offer general guidelines for ignition values. Optimal timing is best found on a dyno or by driving the car.

With this system, total timing is a result of the RPM IGNITION value minus the IGN RET/MANPRESS value.

To program ignition timing, two parameters RPM IGN and IGN RET/MAN PRESS are used. For example, if you want timing at 20 degrees BTDC at 2500 RPM go to RPM IGNITION 2500 and enter 20. For obtaining ignition retard under boost conditions, by entering a value under IGN RET/MANPRESS the system will retard timing by the amount entered at that boost pressure.(See figure 5)

For most engines running adequate octane fuel, a simple timing curve using only RPM offsets often gives excellent results. For high compression, naturally aspirated engines and turbocharged street engines running relatively low octane fuels and where fuel economy is important, a more complex curve taking MAP into account may be required. Timing may have to be retarded at higher manifold pressures to avoid detonation.

Systems not using a MAP sensor will use IGN RET/THROTTLE instead of IGN RET/MAN PRESS. Here, the throttle position sensor provides load information to the ECU. RPM values can be changed every 250 and 64 MAP or TP values are available for you to tailor your ignition curve.

If you have no idea what your ignition curve should look like, programming should be done by somebody who does, SERIOUS ENGINE DAMAGE CAN OCCUR with improper values entered. Excessively retarded timing can cause high exhaust gas temperatures while advanced timing can lead to preignition and detonation.

You should write down what you want your total timing to be with RPM first of all. Most engines want total timing between 5 and 15 degrees BTDC at idle- As RPM is increased, total timing is usually slowly increased from 1500 RPM up to 2500 to 4000 RPM- where full advance is usually in - most engines like 30 to 40 degrees total timing here. Often this figure is maintained right up to the redline- Figure 4 gives a typical RPM only timing curve along the lines above. This will work fine on most engines if you are unsure of what values to enter.

FIGURE 4

RPM TIMING

1000 10

1250 13

1500 16

1750 19

2000 22

2250 25

2500 28

2750 31

3000 32

3250 32

3500 32

3750 32

4000 32

ETC.

For RPM only ignition mapping, enter 0's in all the IGN RET/ MANPRESS or IGN RET/THROTTLE parameter slots.

For Street turbo engines, the IGN RET/MANPRESS parameter slots will have to be used to obtain optimum power and fuel economy running on pump gas.

Some engines may need more ignition advance when cruising to obtain maximum fuel economy. Since this system only provides for retarding timing with regards to manifold pressure, a different strategy is needed to effectively get "vacuum advance".

The easiest way to achieve this type of MAP influenced timing curve is to enter a base value in IGN RET/MANPRESS of say 5 at all the ranges you don't want to retard or advance the timing. This will be the base retard value now instead of 0. At the MAP points that you wish to have total timing "advance", you can enter numbers less than 5. You will have to compensate for this strategy by increasing the values in the RPM IGN ranges by 5 so the total timing will be correct. At higher MAP values you can enter progressively larger numbers to pull back total timing under boost or high load if you wish. If you don't need "advance" under light load cruising conditions, IGN RET/MANPRESS values Can be kept at 0 until you want to pull back timing under boost, This is much easier to understand as well.

It is important to remember that total timing is the result of the RPM IGN value minus the IGN RET/MANPRESS value at that given instant of engine operation.

Figure 5 shows an example ignition map assuming 35 degrees total timing is optimal for best power but the octane rating is too low to tolerate this timing under boost. Timing must be retarded under boost.

FIGURE 5

RPM RPM IGN value IGN RET/MANPRESS Total timing

1000 10 0@-15 inches 10

1250 12 0@-10 12

1500 15 0@-5 15

1750 20 0@ 0 20

2000 25 0@ 5 psi boost 25

2250 30 2@7 psi 28

2500 32 3@8 psi 29

2750 35 4@9 psi 31

3000 35 5@10 psi 30

3250 35 6@11 psi 29

3500 35 7@12 psi 28

Using this map, we would get the following total timing values; 10 degrees at 1000 rpm and -15inches MAP(idle), 35 degrees at 2750 rpm and -5 inches MAP(cruise), 30 degrees at 5000 rpm and 10 psi boost.

There are hundreds of possible timing curves available with SDS to suit any engine, the previous examples are only hypothetical as mentioned before, efficient timing curves are best developed on the dyno.

Mounting the Knock Sensor

We supply a GM sensor for our applications. While other sensors may work with SDS, our system was designed around the GM unit. We can sometimes change a resistor in the ECU to suit other knock sensors.

The sensor is usually mounted in the block, within 2 inches of the top, close to the cylinders. It should never be mounted close any obvious noise generating components such as a fuel pump or camshaft lifters. In most cases, mounting it in the head is also a poor choice because of valvetrain noise.

A thick area of the block with a boss is the best place to drill a (13mm) .500 inch hole. The hole should be (13 to 16rnm).500 to .625 inches deep. Make absolutely sure that it is safe to drill a hole of this dimension where you plan to!

The hole should be tapped with a 9/16 UNF starter tap. Depending on the tap, you should only go in 4 turns to begin with, clean out the chips and try the sensor for fit. Keep tapping one turn at a time until the sensor threads in 4 to 5 turns with hand pressure. Stop tapping when the sensor will screw into the hole 6 to 7 threads with a wrench. Note that the thread on the knock sensor is a tapered thread.

An alternative to drilling into the block is to machine and thread a steel adapter to accommodate the sensor on one end and a stub with the thread to match those in an existing pre-tapped boss in your block, as noted in the previous sections, it may be necessary to change the sensor location if it is impossible to isolate engine noise while still allowing the ECU to identify knocking.

Knock Sensing Programming

The knock sensing option allows you to adjust the sensitivity and selectivity of the ECU to hear knock from the sensor and adjust the amount of ignition retard per knock.

Sensitivity is adjusted in the KNOCK SENSE window of the LCD programmer. This is adjustable between 1 and 16, with 1 being least sensitive.

The amount of knock spark retard is adjusted using the LCD programmer by calling up KNOCK RETARD and changing the reference value, A value of 3 will retard the timing 3 degrees for every knock that the ECU hears. Timing returns to the previous value at a predetermined rate if no more knocks are heard. This rate of return increases with increasing rpm.

It is important to adjust the sensitivity to ensure that the ECU is hearing only knock and not mechanical engine noise. Many engines go through various harmonics and the sensor is so sensitive that it can pick up noises which are not detonation and falsely trigger the sensing circuitry. This may severely retard the timing when in fact no detonation is present. The sensitivity adjustment allows you to tune out low amplitude noise, allowing only true knock pulses through to the ECU.

This condition is best diagnosed and remedied by first entering a 5 in KNOCK RET and 0's in all the IGN RET/MANPRESS slots. Enter 8 in the KNOCK SENSE window. Go to gauge 2 mode. Look at the IGN parameter- Now rev the engine up to redline in neutral with reasonably small throttle movements if possible. The ignition timing in the window should follow exactly what you have programmed in the RPM IGN slots. If you see the timing suddenly retard as you are revving the engine, it means that the knock sensor is picking up mechanical engine noise and the ECU is retarding the timing because it thinks it is knocking. Decrease the KNOCK SENSE value to filter out this noise.

You should be able to rev the engine up in neutral without the knock sensor retarding the timing unless the engine actually knocks. If this happens, there may be too much timing for the fuel octane that you are using. The sensitivity must be set so that the ECU only hears true knocking and no engine "noise". If you can't get satisfactory operation, you may have to try other knock sensor locations on your engine.

Since every engine is different, try experimenting with different KNOCK RET values. 1 to 5 would be the normal range. The maximum retard that the system can deliver is 20 degrees.

If you wish to negate the knock sensing option, you can enter a 0 in the KNOCK RETARD parameter. The knock sensing option can take the place of large amounts of MAP retard in some cases however, total reliance on the sensor while running unrealistically high amounts of spark timing may lead to running problems. We recommend using the knock sensor as a safety device rather than a primary timing control.

Proper location of the sensor and tuning of the KNOCK SENSE along with a proper KNOCK RETARD value are essential for satisfactory operation of this option. Knock control is not a magic bullet. If the compression ratio or boost pressure is too high for the fuel octane you are using, either knock will occur or you will lose power by having to retard timing to prevent it. Constant hard knocking (detonation) will eventually destroy any engine, sometimes within seconds.

Ignition, Coil, Wire and Knock Hookups

The Hall sensor cable is plugged into the center 9 pin plug on the ECU, The yellow wire marked "KS" plugs into the knock sensor. The connections to the coil unit are as follows; Black wire to chassis ground- Red wire to positive switched 12 volts, Green to tachometer and 2 pin Weatherpack plug to 2 pin plug on main harness. The coil pack power wire should use a 15 amp fuse.

Coil placement can be in the stock location in most instances, The coil pack should never be bolted directly to the engine. As always, wires should be well supported and routed away from hot items.

Never turn over the engine or operate the ignition with the spark plug wires disconnected as this will often damage the coils. Coils damaged in this manner are NOT covered by warranty.

Ignition Wires

Note that the F4 system will usually require custom wires for fitment to the GM style coils.

NEVER USE SOLID CORE IGNITION LEADS WITH SDS. EMI/RF suppression wires should always be fitted. We recommend Magnecor wires for best results.

Compression Testing the Engine

Always disconnect +12volt power from the coil pack unit when compression testing. Since the spark plug leads are removed form the spark plugs, the coil pack unit will be damaged if power is not disconnected.

Troubleshooting

Will not start

1. Check power, ground. Test coils.

2. Check Hall sensor alignment.

3. Check MAGNET POSITION parameter and RPM IGN

4. Check timing with a timing light. If timing is not between 0 and 15 deg BTDC then magnets are not properly positioned on pulley. See figure 3.

Miss at high rpm

1. Check Hall sensor alignment.

2. Check Hall sensor air gap.

3. Reduce plug gap.

Intermittent miss

1. Check that Hall cable is not close to high current/voltage wires.

Testing The F Coils for spark

To test the F coils, first disconnect the spark plug wires from the 2 coil packs. Now, wrap a 2 inch piece of solder on uninsulated wire around one output terminal on each coil. Position the ends roughly 1/4 inch from its adjacent terminal on the same coil.

Other wire connections are as follows: Red to +12 volts, Black to ground, Green to tach. Connect a jumper wire to the positive battery post, then momentarily touch the other end to the white wire terminal on the 2 pin coil connector. A spark should jump between the coil terminals on the 1-4 coil. Now, touch the jumper to the black terminal on the 2 pin coil connector momentarily. A spark should jump between the coil terminals on the 2-3 coil.

END.