The ignition coil of the VAZ 2112 engine is the main part of the car’s ignition system, which serves as a conventional low-voltage direct current converter, which comes from the battery or directly from the electric generator into high-voltage voltage for further supplying an electrical impulse to the spark plugs.
In today's article we will learn how to check the ignition module on an injection VAZ-2112 8 valve with our own hands, and also consider step-by-step instructions for replacing this car unit.
Purpose and design of the ignition coil of the VAZ 2112
To create a pulse (spark) between the electrodes of the spark plug of the VAZ 2112 carburetor engine, a “standard”, classic or case coil was used for a non-contact ignition system (BSI), which is a high-voltage pulse step-up transformer with an open or closed magnetic circuit. Its use on “two-wheelers” continued until it was replaced by a two-spark (four-terminal) ignition coil (module) for 8-valve injection engines and an individual coil for power units with 16 valves.
New ignition coil for VAZ 2112
Diagnostics of malfunctions of the VAZ 2112 housing ignition coil for BSZ, nomenclature number 3122.3705 or 8352.12, consists of measuring the resistance of its primary and secondary windings and comparing the obtained data with table values. The resistance of the primary winding of coil 3122.3705 should be 0.43 (±0.04) Ohm, the secondary winding - 4.08 (±0.4) kOhm. The resistance of the coil 8352.12 is respectively 0.42 (±0.05) Ohm and 5 (±1) kOhm. The insulation resistance to ground must be at least 50 MOhm.
If measurement results differ by more than tolerance values, the coil must be replaced. You need the VAZ 2112 ignition coil, with its relatively low price, it is quite reliable and its replacement is rather an exception to the rule.
Ignition module VAZ 2112
The ignition module (four-terminal coil) provides simultaneous sparking in two cylinders (the first and fourth or the second and third). It needs to be checked for serviceability if there is no spark on one or more spark plugs. It is checked using a stand that simulates various engine operating modes and an oscilloscope. Checking “in the field” consists of connecting a known working spark plug one by one to the tips of high-voltage wires, grounding it to ground and, turning the crankshaft with the starter, visually detecting spark formation on the electrodes of the “test” spark plug.
What determines the performance of the coil?
The classic ignition coil or “bobbin”, as it is also popularly called, is essentially a low-voltage voltage converter from the battery and generator to high-voltage, which is then supplied to the spark plugs. That is, this is a miniature electrical transformer.
The ignition coil is a kind of mini electric transformer
The traditional coil, used on carburetor models of vehicles, consists of two windings. The primary winding receives low voltage pulses, for example 12 Volts. As a rule, this is a small number of turns (up to 150) of thick insulated copper wire. The “primary” has 2 terminals on the coil cover. There are much more turns in the secondary winding - up to 30 thousand, but the wire used is much thinner. One end of the “secondary” goes to the “minus” of the primary winding, the other to the central terminal of the coil. In the center of the windings there is a core that enhances the magnetic field. The coil body is insulated, and its cavities are filled with special oil for transformers.
The fundamental characteristic that indicates the serviceability of almost any coil is the resistance of the windings.
Version of the module on the 8-valve VAZ-2112
Two 8-valve engines of different volumes were installed on the twelve-wheeler - 1.5 and 1.6 liters. The ignition modules for these engines are different. The one and a half liter engine has a module with article number 2112-3705010, and the 1600 cc engine is equipped with a module 2111-3705010. A module for a 1.5 liter engine costs about 1500-2100, and the second one is 500 rubles cheaper.
Which is better?
SOATE devices manufactured in Stary Oskol have proven themselves to be the most reliable ignition modules.
Module structure
It consists of two ignition coils and two high-voltage switch switches. The coils are designed to create high-voltage pulses.
In essence, it is a simple transformer that has two windings: a primary winding, with an induction voltage of approximately five hundred Volts, and a secondary winding, with an inductive voltage of at least twenty kiloVolts. Everything is placed in one housing with one connector for signal wires and four for high-voltage.
Structure of the ignition coil module of the VAZ 2112
The operation of the ignition module is based on the “idle spark principle”. The module is capable of distributing a spark in pairs: to the first and fourth, second and third cylinders when transmitting pulses from the electronic control unit.
Video on repairing KZ VAZ
Often, when the ignition module breaks down, the car owner immediately runs to the store and buys a new one. But, for the VAZ-2112 there is an alternative method - repair. Of course, without proper knowledge in auto electrics, it will be difficult to understand all the circuits and communications. This article will tell you in the most accessible way how to repair the ignition module with your own hands.
Malfunctions of ignition modules on VAZ-2112
The process of removing the ignition coil on a VAZ 2112
If the VAZ 2112 engine starts running intermittently or does not start at all, the cause of the problem may be the ignition module.
Characteristic symptoms of a malfunction of the ignition module of the VAZ 2110:
- insufficient engine power,
- when accelerating the car jerks,
- either 1 and 4 or 2 and 3 do not work at the same time,
- the engine does not start.
It should be noted that on the VAZ-2112 one of the coils is responsible for the operation of cylinders 1 and 4, the second - for cylinders 2 and 3. If one ignition coil fails inside the monolithic block, two cylinders stop working at once.
To eliminate all other components of the ignition system, make sure that the spark plugs are in working order.
Installation of a new ignition module for VAZ 2112
To do this, unscrew them and check the spark on each of the spark plugs by cranking the engine with the starter and placing the spark plug with the high-voltage wire on the head so that the body (threaded part) of the spark plug touches the engine mass.
If there is no spark or it is weak, replace the spark plug with one that is known to work. If this does not lead to anything, check the high-voltage wires.
Thus, we will exclude spark plugs, caps and high-voltage wires from the list of non-working elements. Next we will check the ignition module.
PRINCIPLE OF OPERATION OF THE MODULES
The VAZ ignition module is an improved engine starting system. The principle of its operation is not very different from conventional systems. If in older systems the high-voltage voltage was generated by opening the contacts in the ignition distributor, then in the module the signals from the control unit serve as a pulse generator.
The control unit collects signals from sensors on the engine, generates a control pulse and sends it to the ignition module of the VAZ 2115. In it, a high-voltage voltage is generated from the on-board network voltage and sent to the cylinder spark plug to ignite the air-fuel mixture.
Removing and replacing the ignition coil
In order to replace the module (ignition coil) on a VAZ 2112, you must perform the following steps:
- Before starting work, be sure to disconnect the battery by disconnecting the “-” terminal from it. (How to de-energize a battery.
- Then, approaching the ignition coil, disconnect one single high-voltage wire from its central part.
- Next, use a wrench to remove the two side nuts that hold the ends of the wires in place on the side of the coil.
- Next, when the nuts are unscrewed, remove both side wires from the coil.
- And to complete the operation, unscrew the two side nuts securing the ignition coil itself to the bracket.
- And then remove the coil from the car engine.
ABOUT THE POSSIBILITIES OF MODULE REPAIR
Most breakdowns of this device lead to its replacement, but sometimes it is possible to repair the ignition coil to return it to service. This is especially true in cases where moving or tapping changes the behavior of the motor. If you have the ability to use a soldering iron and a multimeter, you can try to get it back into operation.
You need to remove the metal back cover, under which the electrical parts of the module are filled. You need to try to carefully get rid of the silicone and its “insides” will be revealed to your eyes. Find broken or “bad” contacts and solder them.
The conductors in the block are aluminum, so special solder is needed to solder them.
After this, close the back cover and check its functionality. If the repair result is positive, you need to open it again and fill the inside with silicone.
If the result is negative, then the block must be replaced. True, owners with extensive amateur radio experience continue to “dig” further. You can try replacing the electronic switches. Basically, these two elements become the culprits of failures of the engine starting system.
Do-it-yourself installation of the VAZ 2112 ignition module
- Having picked up the new coil, first install it in its place by tightening the two nuts that secure it.
- Then place two wires on the sides of the coil and secure them with retaining nuts.
- When installing two side wires, pay attention to the markings that are marked on the sides of the ignition coil (see photo below). So this marking indicates which terminal of the coil should be connected to this or that wire. The blue wire must be connected to the “B” marking, and the red wire must be connected to the “K” marking!
- Then place the high-voltage wire on the central part of the ignition coil.
- And then install the negative terminal on the battery.
On old ignition coils, as a rule, instead of the letters “B” and “K”, the designations “-” and “+” are used, which means the same thing, but only in signs. The blue wire must be connected to the “-” sign, and the red wire must be connected to the “+” sign!
WHERE TO FIND THIS MODULE
It is hard to believe that the driver who undertakes to check or repair this device does not know where it is located. Well, for those who don’t know, we’ll tell you. It’s easy to find it, find at least one high voltage wire, and walk your hand along it from the spark plug to the plastic case that belongs to the module.
From the picture its location becomes clearer.
MH errors
The following errors are associated with the malfunction of the MH:
- P0351 - coil breakage of cylinders 1-4.
- P0352 - cylinder 2-3 coil breakage.
- P3000 (P3001 P3002 P3003 P3004) - multiple misfires.
The faulty module must be replaced (MZ replacement) or repaired (Ignition module repair).
A common cause of this error can be both spark plugs and high-voltage wires - they need to be replaced (How to replace high-voltage wires? How to replace spark plugs?).
