DISTRIBUTORLESS IGNITION SYSTEMS (DIS)

    Distributorless ignition systems (DIS) have been in existence for nearly ten years now, and also have removed a lot of the constant maintenance that was once connected using the ignition system. No distributor means there's no distributor cap or rotor to exchange, with no difficult vacuum or mechanical advance systems to result in timing problems. Consequently, DIS ignition systems are pretty reliable.

Nevertheless, that doesn't mean they're trouble-free. Failures can and occur for numerous reasons. So understanding how to recognize and identify common DIS problems can help you save lots of uncertainty next time you encounter an electric train engine that cranks but will not start, a treadmill that runs but is missing or misfiring on a number of cylinders.

If the engine cranks but won't start, could it be fuel, ignition or compression? Ignition is often the simplest from the three to check on because of all engines, all you need to do is accomplish a plug wire and appearance for spark once the engine is cranked. On coil-over-plug DIS systems, you will find no plug wires so you've to get rid of a coil and employ a plug wire or adapter to look into the spark.

If there's no spark in a single cylinder, try another. No spark in almost any cylinder would definitely indicate a unsuccessful DIS module or crankshaft position sensor. Many engines which are outfitted with electronic fuel injection also employ the crankshaft position sensor signal to trigger the fuel injectors. So, if there's no spark with no injector activity, the issue is likely within the crank position sensor. No spark in just one cylinder or two cylinders that share a coil would let you know a coil has most likely unsuccessful.

DIS COIL Inspections

The coils in DIS ignition systems function just like individuals in regular ignition systems, so tests are basically exactly the same. However the driveability signs and symptoms triggered with a weak coil or dead coil is going to be restricted to a couple of cylinders instead of all of the cylinders. Many DIS systems make use of the "waste spark" setup where one coil fires a set of spark plugs which are opposite each other within the firing order. Others, such as the more recent coil-over-plug systems, possess a separate coil for every spark plug.

Individual DIS coils are examined in basically exactly the same way as epoxy-filled (square-type) ignition coils. First, isolate the coil pack by disconnecting all of the leads. Set the ohmmeter within the low range, and recalibrate if required. Connect the ohmmeter leads over the coil's primary devices, and compare the main resistance reading through to specifications (typically under 2 ohms). Then connect the ohmmeter leads over the coils； secondary devices and compare the secondary resistance reading through to specifications (typically 6,000-30,000 ohms). If blood pressure measurements are outdoors the required range, the coil is defective and must be changed.

If calculating the secondary resistance of the DIS coil is tough due to the coil’s location, try getting rid of the wires in the spark plugs and measure secondary resistance with the plug wires instead of in the secondary devices around the coils. Just be sure you include no more than 8,000 ohms of resistance per feet for that plug wires.

DIS MODULE & SENSOR Inspections

Here‘s just a little trick which will literally demonstrate if your DIS module and it is crankshaft sensor circuit will work: connect a halogen headlamp towards the spade devices that mate the DIS module towards the coils. A headlamp is suggested here since it puts much more of a lot around the module than the usual test light. When the headlamp flashes once the engine is cranked, the DIS module and crankshaft position sensor circuit are functioning. Therefore, the issue is within the coils.

When the headlamp doesn’t expensive, or there‘s no current towards the module or coil pack once the engine is cranked, the issue is probably within the crankshaft sensor circuit. Of all automobiles, a poor crank position sensor will often set a fault code, so make use of a scan tool to look into the code. Or, look into the crank sensor itself. Magnetic crank sensors could be examined by unplugging the electrical connector and checking resistance between your appropriate devices. If resistance isn't within specs, the sensor isn't good and must be changed.

Magnetic crank position sensors provide an alternating electric current once the engine is cranked so a current output check is yet another test that may be carried out. Using the sensor connected, browse the output current over the appropriate module devices while turning the engine. If you notice a minimum of 20 mV around the AC scale, the sensor is nice, meaning the fault is most likely within the module. When the output current is low, take away the sensor and inspect the finish from it for rust or debris (magnetic sensors will attract iron and steel contaminants). Clean the sensor, re-install it and test again. Make certain her proper air gap (if adjustable) since the spacing between your finish from the sensor and also the reluctor wheel or notches within the crankshaft will modify the sensor’s output current. When the air gap is true and output continues to be low, switch the sensor.

Hall effect crankshaft position sensors normally have three devices one for current feed, one for ground and something for that output signal. The sensor should have current and ground to make a signal, check these devices first by having an analog voltmeter. Sensor output could be checked by unplugging the DIS module and turning the engine to ascertain if the sensor creates a current signal. The voltmeter needle should jump every time a shutter edge goes through the Hall effect switch. If observed with an oscilloscope, you need to visit a square waveform. No signal would let you know the sensor has unsuccessful.

DIS PERFORMANCE PROBLEMS

In situations where the engine begins and runs but doesn't succeed (insufficient energy, poor gas mileage, spark knock, elevated pollutants, etc.), the issue might be outdoors the DIS system. First, the person coils ought to be examined to make certain their primary and secondary resistance is at specs. When the coils are okay, the electronic spark control circuit might be receiving bad information from a few of the engine‘s other sensors.

Low MAP sensor output current or perhaps a coolant sensor that reads cold constantly allows more spark advance than usual. This, consequently, could cause detonation (spark knock) problems once the engine is under load. Also can a faulty knock sensor or perhaps an EGR valve that isn’t working.

High MAP output current or perhaps a misadjusted throttle position sensor might have the alternative effect and make the spark control system to retard timing a lot more than normal. Retarded timing will reduce performance and gas mileage.

Don‘t forget, too, that regular secondary ignition problems may also cause misfires with DIS just like a regular ignition system. A poor spark plug wire or perhaps a worn or fouled spark plug will act as being a weak or bad DIS coil. So when you locate an ignition problem that's isolated one cylinder, remove and inspect the spark plug and plug wire to eliminate individuals options.