I'm from Estonia. I have an audi S2 Avant from 1994. The engine is ABY. The goal is to use VEMS 3.3 to fully drive the engine for everyday use and for some racing.

Currently the car has:

Current Status:


I have tryed to upgrade the firmware from 1.1.27 to 1.1.74. After some attempt and fail I got the engine to runnung. But i still have one problem. When the engine RPM goes from about 1000 to 3000 the WBO2 goes to more than 21 but the engine still runs fine. What can cause this? The config file is on this link:

[New Config]

Done to this far:

The firmware is upgraded to 1.1.27beta5 using 16x14 maps.

Because the VEMS was ordered with standard connectors i had 2 choises. Use the default VEMS connectors and rebuild the car electric system or assemble the VEMS with original 55pin Motronic connector. Because i had one old audi equ this part wasnt hard. Below is the table i used to connect the wires. Note, that the WBO2 and 1-Wire cables are connected to free pins in Audi equ. The power for WBO2 is taken from Motronic connector pin 37.

Pin Function / Assignment Input or Output wrt ECU Schematic References Wire Colour at ECU VEMS Pin
1 Power output stage for ignition, cylinder #3 OUTPUT N122 pin I3 gn/ws EC36-34
2 Power output stage for ignition, cylinder #2 OUTPUT N122 pin I2 li EC36-33
3 Fuel Pump Relay, 0V. Also provides 12V power for various components. OUTPUT (0V) J17 br/gn EC36-17
4 Idle Air Control Valve, 0V OUTPUT (0V) N71 pin 2 gn/sw EC36-6
5 Evaporative emissions frequency valve, 0V OUTPUT (0V) N80 pin 1 ws EC36-12
6 Air conditioning compressor control. Normally an input in conjuction with pin 41 , but can also be used to turn off A/C compressor when maximum engine power is required INPUT / OUTPUT A/C gn/sw -
7 Mass Air Flow (MAF) sensor signal INPUT G70 pin 3 sw/ws -
8 Camshaft Position Sensor (Hall Sender), Pin #2 INPUT G40 pin 2 gn EC36-13
9 Barometric pressure sensor INPUT F96 pin 1 gr -
10 0V ground/shield for various sensors 0V G39, G70, G4, G28, G61, G66, F60, G40 br/ge -
11 Knock sensor I (For cylinders 1 - 3) INPUT G61 ws KNOCK1
12 +5V reference voltage for various sensors OUTPUT G69 pin 1, G40 pin 1, F96 pin2 ro/sw EC36-28
13 OBD connector (L-wire) INPUT OBD ws/ro -
14 0V ground 0V - br/ro EC36-5
15 Default FREE - WBO2 (NERST CELL SIGNAL) pin-1 - - - EC18-13
16 Fuel injector -ve pulse, cylinder #5 OUTPUT N83 pin 2 br/ro EC36-9
17 Fuel injector -ve pulse, cylinder #2 OUTPUT N31 pin 2 br/bl EC36-19
18 Permanent 12V supply voltage 12V INPUT S27 ro/ws Flyback
19 0V ground/shield for various sensors 0V G39, G70, G4, G28, G61, G66, F60, G40 br/ge EC36-26
20 Power output stage for ignition, cylinder #4 OUTPUT N127 pin I3 ro/sw EC36-36
21 Power output stage for ignition, cylinder #5 OUTPUT N127 pin I2 gn EC36-11
22 OBD for Malfunction Indicator Lamp (MIL) - Blink Codes OUTPUT OBD gr/br -
23 Power output stage for ignition, cylinder #1 OUTPUT N122 pin I1 sw/bl EC36-35
24 0V ground 0V - br/ro EC36-32
25 Mass Air Flow (MAF) sensor, burn-off signal OUTPUT G70 pin 4 bl/li -
26 Mass Air Flow (MAF) sensor, electrical ground INPUT G70 pin 2 sw/gn -
27 Switched 12V supply voltage (Ignition ON) 12V INPUT S32 sw EC36-25
28 Oxygen / Lambda sensor INPUT G39 gn EC18-13
29 Knock sensor I (For cylinders 4, 5) INPUT G66 gn KNOCK2
30 0V ground 0V G61, G66. G69, F96, G62, G42 sw/li GND, near JP20
31 Fuel consumption signal OUTPUT J128/189 br/sw -
32 Charge pressure signal (NOT used on the S2) OUTPUT - - -
33 Wastegate frequency valve control signal (Switched 0V) OUTPUT N75 pin 2 gn/ge EC36-18
34 Fuel injector -ve pulse, cylinder #3 OUTPUT N32 pin 2 br/gn EC36-8
35 Fuel injector -ve pulse, cylinder #4 OUTPUT N33 pin 2 br/ws EC36-20
36 Fuel injector -ve pulse, cylinder #1 OUTPUT N30 pin 2 br/sw EC36-7
37 Switched 12V supply voltage (via fuel pump relay - activated by ECU). Also related to 'holdover relay' with ECU for the MAF. Probably for burnoff - assuming that pin 25 burnoff trigger is a 0V output pulse. In which case this pin is pulled to 12V with the engine running and is used to empower the MAF burnoff sequence with the engine off. 12V N30, N31, N32, N33, N83, G70 bl/sw WBO2- Power
38 Coding Plug (where applicable) INPUT - br/bl -
39 Coding Plug (where applicable) INPUT - ws/sw -
40 Engine speed signal (RPM) OUTPUT G5 (Tacho) li EC36-16
41 Air conditioning status - informs the ECU if A/C is ON or OFF INPUT A/C sw/ge JP11-CH7
42 Default FREE - WBO2 (PUMP+) pin-6 - - - EC18-9
43 Default FREE - WBO2 (PUMP-) pin-5 - - - EC18-7
44 Intake air temperature INPUT G42 sw/ge EC36-2
45 Coolant temperature INPUT G62 ro/gn EC36-14
46 Multi-Function Thermal Switch INPUT F76 pin 2 (R) bl/ws -
47 Crankshaft reference position sensor (62 degrees BTDC on cylinder #1) INPUT G4 ro VR2 Inp, JP20-Pin1
48 0V reference for crankshaft sensors. 0V G4, G28 li-G4, gr-G28 GND, JP20-Pin2
49 Crankshaft speed sensor (135 teeth on flywheel starter ring) INPUT G28 bl EC36-27
50 Vehicle speed signal (VSS from speedometer) INPUT G21 ws/bl -
51 Default FREE - 1-Wire XXX - - - 1-WIRE EC18-16
52 Throttle position switch (Idle detection) INPUT F60 pin 6 gn/li -
53 Throttle position potentiometer (Throttle angle) INPUT G69 pin 3 gn/bl EC36-1
54 Default FREE - WBO2 (HEATER) pin-4 - - - EC18-18
55 OBD connector (K-wire) INPUT / OUTPUT OBD gn/ro -

I have made separate board with 2 x SN754410 stepper drivers to drive the ignition directly from standard outputs. The board is connected to top of the Genboard to the pinholes for ignition transistors. This way i can drive the audi ignition amplifiers from VEMS ignitoin channels.

The trigger is default Auditrigger. From InputTrigger/AudiTrigger


Old Status:


Thanks to Sambas the boost is under controll now. The problem came from wrong vemsv3.ini file. I think it happened because i tryed the older version 1.1.24 and copied it over because it gave less errors on importing MegaTune configuration fail.

Now there is one problem left, the idle.

The cold (8C) engine starts nicely and rews about 1100rpm wery smoothly until the lambda get's in. Then the engine rews from 1000 to 1100 rpm with 1-2 sec intervals.

If the engine is hot then it revs about 1000-1100rpm.

The problem is, that the engine rpm can't be adjusted. Not the cold or warmed up values. Only things that work are the "Idle afterstart RPM, added value" and "idle afterstart duration", but these works only with hot engine.

The second smaller problem is with boost. When the turbo start's to make pressure, the boost jumps 0,2..0,3 bar over the set limit and then falls quickly down to set value. Can i do something about this?

Here are the current config files:

[MegaTune], [Config] and [Tables]


In general the car runs pretty well.

The car had an unstable idle. Because i have big injectors for this engine (Audi ABY 2226cc/5cyl and ~650cc injectors) i was thinking about adding higher Flyback. I used this [FlyBack]. Because i had BY500 dieodes and they have higher amper rating, i used 4 in series not 3. So the Voltage drop may still be ~6V. After installing this, the engine idles mutch better.

But i still have few problems:


It took 1 and half a day to get the engine running. The reason was simple, the dwell time was too short. I got the initial config from a guy in Estonian Audiclub. He is using the coilpacks from 1.8T. On second day after testing the original EQU and VEMS with leds attached to injector connectros and sparc plugs to coils, I found out that the firing order was right but the sparc was allmost missing with VEMS. I connected my scope to find out what is different and found that the coil chargetime with VEMS was about 2ms (Megatune shows 1.8ms) but with original EQU it was 15ms! after changing the charge time to 12.5ms that gives 15ms in real life the car started.

Now with cold engine the car runs fine but after the temperature reaches to about 60C the iddling starts to go bad.

Needs some more testing.