Audi A4 B5 (VW)VR6 12V 2.8 engine.

Stock VR 60-2 trigger wheel in the crankcase.


"bosch motorsport" ignition coil

continental flexfuel sensor connected to Whspeed1st.


6pcs low-z injector, 8ch Active flyback.

removable SD card,

Serious Primary trigger VR wheel "runout" (systematic amplitude variations within 1 rotation) suspected, at 2300 RPM less ptrig error. See InputTrigger/RunOut .

Not this v3/14333 ECU, but a very similar standard VEMS ECU (VR/HALL but sectrig disabled) was tested with a runout primtrig signal:

Russian roulette install

The last 2..3 makes it extremely risky and waste a lot of time, basically impossible to support. In case of any install issue, without scopeshots we are showing darts in the dark, (sometimes making things even worse, and not knowing).

The battery (+) disconnected and shorted to GND before first cranking and startup. The HIFI audio system has had a big capacitor so it was discharged and sparked

TDC_delay set up with strobe light,

"Less tr. error" flag and misfire at 1800-2000rpm.

VR sensor polarity was good, but tried to swap without result.

Originaly r30=27K but after tried, 1K, 10K, 22K, 33K, and removed resistor(without pullup) without result, no different. Everytime got "tr error" around 2krpm.

R181=150K originally, I changed it to 270K, This was the only improvement: The "tr error" came around 2300rpm

I tried to increase the R181 but the "tr error" came at lower RPM

The best setup was: r30=22K, r180=270K.

Originally lm1815 pin5=open (measured 4.95V, interestingly), i jumpered pin5=5V and changed R30 from 1k to 33k again, No result.

Simple input threshold without noise suppression

HALL input (as a last experiment).

I tried to solder the ECU from VR to HALL as Marcel advised, R30= 1K. Ec18/27 voltage = 2.40V, no rpm signal read when cranking.

This path was abandoned without trying to adjust input threshold to trigger (so engine did not start at all).

Another possible path (this was not attempted) is to use an NPN inverter (external or internal)

This is similar to the simple triggerdetection with no noise suppression that simpler circuits use. Usually inferior, but might be the way to go if toothamplitude changes are extreme, but noise is not a problem.

Improvised bench-setup

I tried the "Play trigger" tool

Engine, body, battery and engine harness GND points checked and made to stronger. I tried to change the GND of the engine harness location from body to cylinder head, but no result again.

Hard to check the trigger wheel runout because it's located in very bad position on the engine. This engine was running fine with another standalone ECU this before.

Tried to lower the ignition dwell time from 3.01ms to 1ms maybe the coils makes electronic noises.... no result.

I disconnected WBO sensor but no result.

I made new shielded cable separated from the harness, GNDed(shield, VR(-) ) everywhere, no different

VR sensor resistante=~900ohm it's OK, I changed the sensors, tried 3pcs, without result.

I didn't have scope. I would have made scopeshots if i would have had.



From what I see in your logs and from my own experience I can say that trigger wheel in that engine is fucked up, I mean one tooth is bent or something, maybe the crank was dropped on hard surface and it's tooth 46 I believe.


Tooth 45 time is slightly off indeed, but nothing extreme.