Main Project Page Link:

Contains mct/mcd dumps, and links to the wiring information

Wiring Page:

Essential info needed to investigate

Because fuel-dump can be caused by either misconfiguration, or it can be related to HW damage (perhaps at the same time as the mcp3208 damage), we need to be able to verify configuration with respect to wiring.

Please do not ask for help until this is filled in:

( IssueReports can give hints on other useful info )


(these are several weeks old, after the first two fuel-dumps.'''

  • we will verify ... _channel and h[0] if some might open the injector and flood the engine


(Likely related to the mcp3208 damage)

Problem #1 when turning ignition key-on to start the engine, or cranking the engine and unsuccessful startup, the ECU "locks up" and causes the injectors to stay open and fuel pump to run, hydralocking the motor.

This has happened now 4 or 5 times.

That means to plan

  • wiring (inputs and outputs)
  • choose firmware and trigger setups to start from (reference to similar setup)
  • firmware and trigger same as VEMS #857, which has been running for about a month. This information is useless for helping.
  • matching outputs h[0] and h[2]. If you instruct the ECU to activate an output and the outputs control injectors and fuelpump (it is possible to activate max 8 injector outputs at the same time, see GenBoard/Manual/DigitalOut/Table
  • in case of any output issue, all output channels are interesting (mcd dumpDone, variables ending with _channel except shiftcut_channel that is not output but input selection)

HW connection problem is also possible

- Overkill, please see Wiring details above
  • eg. "stealing input switch ground" (not from EC36pin26 ground but) from chassis while some or all grounds are missing (or chasses to engine ground missing ?)
- Engine to Chassis Ground present

- Only thing I can think of is I used chassis ground for my Autronic air/fuel analyzer deleted, did not use analyzer during the last 3 fuel-dumps

- Connected to EC36-23 and to FJO injector driver. - Autronic meter supplies 0-5 volt only - confirmed.

- Launch Control Pull-up is to Pin 29 5v

- No switch used
  • This is only for accident. (especially if there is no external max 1A fuse and 18V transient diode in the harness)

other possible (though unlikely) causes:

- I am using a custom .ini file (by me). I will e-mail this to the Webshop as the File Manager will not allow it to be uploaded.

- At the top of the .ini file this appears:

"vems.ini for Megatune2.25 + vems firmware 1.0.x (stable1_0 branch)"

** Yes, the car has a small battery that went low 20+ times in a week. Battery charger was used, jumper cables were used only AFTER the second ECU lockup.

***Update: battery was replaced with full size battery. 3 more fuel-dumps since then

MCP3208 damaged

- Note that the fuel was injected Twice, the first time (days before) there was no issue with the analog inputs, so maybe this timeline will help you diagnose the chain of events?


Problem #2 - perhaps also related to the same damage that damaged mcp3208 (although mcp3208 is not directly involved in wbo2 control).

The wideband O2 readings are OK at idle and low engine RPM, but jumps around greatly at medium RPM and higher, making the sensor unusable. The pumpzero_pw and Nernst values were used as supplied with the VEMS, and the sensor was calibrated to 20.9% O2.

- Wideband problem was from the start, mcp3208 did not "die" until 7 days later. - Any more information? Are you thinking the voltage spiked over 5v? How can I prevent this from happening?

Minor Questions

1) Map Multiplication

- Injector Settings:

InjOpen?: 0

Rampup: 1008

Battfac: 4080

Battfac: (us) 304

PWM DC: 0% (should this be 100%???)

PWM Peak Time: 25.5

Divider: 2 (using 2 Injector Outputs 10(8+2)and 5(4+1))

Fire Banks: Alternate

2) Ignition Output Power

- TODO: find out is 255 ohm works and then specify that from now on for all orders (I have many applications using VAG COP coils)

- I would prefer to use logic level (or stepper) to trigger MSD rather than IGBT (less heat(clamping platye is tricky to get "right" and not "bow up" in middle, more reliable as less components are being used)

  • I ended up changing the ignition to a Webshop 2x2 coil pack using 2 12v drivers.