Hi.
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:
- Holset HY35 turbo
- Siemens 727cc injectors
- VEMS Round_WBO2_EGT with both WBOxygen and EGT.
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 | 2 | EC36-34 |
| 2 | Power output stage for ignition, cylinder #2 | OUTPUT | N122 pin I2 | li | 2 | EC36-33 |
| 3 | Fuel Pump Relay, 0V. Also provides 12V power for various components. | OUTPUT (0V) | J17 | br/gn | 2 | EC36-17 |
| 4 | Idle Air Control Valve, 0V | OUTPUT (0V) | N71 pin 2 | gn/sw | 2 | EC36-6 |
| 5 | Evaporative emissions frequency valve, 0V | OUTPUT (0V) | N80 pin 1 | ws | - | - |
| 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 | 2 | 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 | 2 | KNOCK1 |
| 12 | +5V reference voltage for various sensors | OUTPUT | G69 pin 1, G40 pin 1, F96 pin2 | ro/sw | 2 | EC36-28 |
| 13 | OBD connector (L-wire) | INPUT | OBD | ws/ro | - | - |
| 14 | 0V ground | 0V | - | br/ro | 2 | EC36-5 |
| 15 | Default FREE - WBO2 (NERST CELL SIGNAL) pin-1 | - | - | - | 2 | EC18-13 |
| 16 | Fuel injector -ve pulse, cylinder #5 | OUTPUT | N83 pin 2 | br/ro | 2 | EC36-9 |
| 17 | Fuel injector -ve pulse, cylinder #2 | OUTPUT | N31 pin 2 | br/bl | 2 | 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 | 2 | EC36-26 |
| 20 | Power output stage for ignition, cylinder #4 | OUTPUT | N127 pin I3 | ro/sw | 2 | EC36-36 |
| 21 | Power output stage for ignition, cylinder #5 | OUTPUT | N127 pin I2 | gn | 2 | 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 | 2 | EC36-35 |
| 24 | 0V ground | 0V | - | br/ro | 2 | 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 | 2 | EC36-25 |
| 28 | Oxygen / Lambda sensor | INPUT | G39 | gn | 2 | EC18-13 |
| 29 | Knock sensor I (For cylinders 4, 5) | INPUT | G66 | gn | 2 | KNOCK2 |
| 30 | 0V ground | 0V | G61, G66. G69, F96, G62, G42 | sw/li | 2 | 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 | 2 | EC36-18 |
| 34 | Fuel injector -ve pulse, cylinder #3 | OUTPUT | N32 pin 2 | br/gn | 2 | EC36-8 |
| 35 | Fuel injector -ve pulse, cylinder #4 | OUTPUT | N33 pin 2 | br/ws | 2 | EC36-20 |
| 36 | Fuel injector -ve pulse, cylinder #1 | OUTPUT | N30 pin 2 | br/sw | 2 | 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 | 2 | 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 | 2 | EC36-16 |
| 41 | Air conditioning status - informs the ECU if A/C is ON or OFF | INPUT | A/C | sw/ge | 2 | JP11-CH7 |
| 42 | Default FREE - WBO2 (PUMP+) pin-6 | - | - | - | 2 | EC18-9 |
| 43 | Default FREE - WBO2 (PUMP-) pin-5 | - | - | - | 2 | EC18-7 |
| 44 | Intake air temperature | INPUT | G42 | sw/ge | 2 | EC36-2 |
| 45 | Coolant temperature | INPUT | G62 | ro/gn | 2 | 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 | 2 | VR2 Inp, JP20-Pin1 |
| 48 | 0V reference for crankshaft sensors. | 0V | G4, G28 | li-G4, gr-G28 | 2 | GND, JP20-Pin2 |
| 49 | Crankshaft speed sensor (135 teeth on flywheel starter ring) | INPUT | G28 | bl | 2 | 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 | 2 | EC36-1 |
| 54 | Default FREE - WBO2 (HEATER) pin-4 | - | - | - | 2 | 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
Changed:
- 10k pullup to 5V for crankhome VR signal
- R182 (100K) replaced with 0R resistor
- R57 (75K) for primary trigger is replaced with 33K
- 1uF cap parallel with C40
- C103 220nF removed
- Connected JP2 with JP7
- Connected SJ4 Pins 1 and 2
- Shorted SJ7
- Installed second LM1815 for crankhome-VR.
- R10 (MAT sensor pullup 1K) is replaced with 510R
- Installed R3, R4 and C2 for secondary KNOCK channel.
- Installed 1R resistor on place L4
Status:
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 with VEMS (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 runns fine but after the temperature reaches to about 60C the iddling starts to go bad.
Needs some more testing.