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 @ ~3.2bar = 650cc
- VEMS Round_WBO2_EGT with both WBOxygen and EGT.
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:
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 ECUá||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||-|
|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|
|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|
|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
- 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
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 (8░C) 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?
- [log] file. Look at time 2384.995.
- use 2 PWM solenoid valves, one to the bottom and one to the top chamber of the wastegate. Connect the valves in parallel electronically, but antiparallel pneumatically. That gives better response, and lower overshoot if tuned right. Higher D value can be tried if it gives lower overshoot.
Here are the current config files:
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:
- For some reason i can't set the engine idle speed. It idles by itself about 1000-1100RPM.
- Havn't figured out how the boost control works. For some reason there is fuelcut about 4500PRM @ 200kpa.
- Fixed now. vemsv3.ini was from wrong version.
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.
- 12.5 msec is very long dwell, it can easily cause problems. (probably only acceptable with certain ignition coils, during cranking, eg. VBATT=9V)
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.