Ignition Output VW 1.8t Coil Packs,
Wasted Spark with MegaSquirt/Extra v3.0

MegaSquirt can drive VW coil on plug devices with built in igniters.. Use this configuration if you are driving the VW 1.8L and 1.8t 4-pin coil. These coils are typically found on 2001 and later Audi and VW Passat, Jetta, Golf, Seat and Skoda.

Check if you have the 120 -500 ohm pull down resistors in the coil, using a multimeter set to resistance to a suitable range, check between pin 2 and 3. If you have a reading of around 120-500 ohms you need to go the PNP transistor (arrow pointing toward center) driver route, if the impedance is higher, say ~1k a NPN (arrow pointing to ground) should work. Coil PN 06B 905 115 L and R have been tested with the below documented method. Use the 'R' revision since the earlier 'L' revision has reliability issues.

Earlier than 2001 coils, PN - 06B 905 115, 06B 905 115 B and E have not been tested with these connections but have been reported to work using the outputs of the LED drivers. Both earlier and later coils should work with the below setup. Later coils (L,R) have been tested with this setup.

Resistance measurement at pin 2 and 3:
greater than 1k > use NPN driver such as the LED drivers
less than 500 ohm > use PNP driver as shown below (2N4033)

The coil pack connections:
Pin 1: Connects to Pin 1 on all other coils and then to +12v from engine control relay (or fuel pump relay).
Pin 2: Signal ground
Pin 3: Signal from ECU (0, +5v)
Pin 4: Power ground (Chassis)

Dwell: 2.6 ms
Cranking dwell: 3.0 ms
Spark Output Inverted: No
LED17(D14) function: Spark output A
LED19(D16) function: Spark output B

The above connections are for the L to R coils. The PCB diagram shows where to connect the resistors that go to the 2N4033 transistor. The schematic shows how to add two transistors for each bank of two coils, spark A and spark B. With this Wasted Spark setup, two plugs will fire at the same time, one plug at the power stroke and one at the exhaust stroke. Below is the schematic for connecting the coils. Note the signal ground goes to the common ground and/or pins 7-11 on MS. The power ground should go to the head or some other nearby good ground connection. The +12V will have less noise if a 20uF/50V capacitor or a condensor usually found next to ignition coils is attached from the +12V to power ground.

You may wish to disconect the +12v feed to the coil untill you have set up the inverted/not inverted setting correctly. You wish to be in a state where, when the engine is not running, and ignition is on, the output labled "Spark A" on the diagram is sitting at ~0v


Here are a few pictures of the pushdown VAG COPs. People running the factory ECU interchange these with the Hitachi Bolt down COPs and vice versus. They use the same plug and pinout.