Questions and Answers
Ranger Pings
Q. Vehicle: 1990 Ford Ranger 2.3 liter, 5 speed, standard transmission.
Question #1: What controls the advance/retard on a distributerless ignition system?
Question #2: Why does the pinging come and go randomly, up hill, flat road under most any type of acceleration in all gears? Engine temperature does not seem to make any difference.
Statement: I run 91 octane fuel, change oil at 3,000, clean air filter, fresh timing belt. The vehicle passed California smog test with flying colors. I am stumped as to how to get the pinging to stop. I thank you in advance for any advice.
Phil
A. Basically in your vehicle the Distributorless Ignition System (DIS) consists of a crankshaft mounted Dual Hall Sensor, two 4-tower DIS coil packs, and a DIS ignition module.
The DIS eliminates the need for a distributor by using multiple ignition coils. Each coil fires two spark plugs at the same time. The coils are paired so that as one fires during the compression cycle the other fires during the exhaust stroke. The next time the coil is fired, the plug that fired on the exhaust stroke will fire on the compression stroke and the one that was on the compression stroke will fire on the exhaust stroke (the spark in the exhaust cylinder is wasted but little of the coil energy is lost).
Two coils are mounted together in a "coil pack". Each coil pack has two tach wires, one for each coil. Since there are two plugs per cylinder, two coil packs are required. One is called the Right Coil Pack (on right side of engine) and the other, the Left Coil Pack (left side). The Right Coil Pack and plugs operate continuously but the Left Coil Pack and plugs may be switched on or off by EEC-IV processor. The EEC-IV processor computes the spark angle, dwell and timing for the ignition system.
The pinging may be due to a bad Knock Sensor (KS). The KS generates an AC voltage when it encounters mechanical stress or vibration, such as engine detonation. Knock sensors generate a small voltage spike when vibration or a knock from detonation occurs. The bigger the knock or vibration, the bigger the spike the KS generates. Certain higher frequencies of the signal identify detonation, or "pinging." When these frequencies are received by the control unit, the PCM retards ignition timing in an attempt to prevent further detonation.
It is also possible that the PCM itself is bad. I would suggest having it tested with a scan tool before I condemn it.
Additional Information provided courtesy of ALLDATA
