Injectors stuck on after priming pulse

I have two 4 cylinder cars which has developed similar symtoms. Both have Volvo 4 cylinder red engines, both run 1.2.31 firmware, Bosch Motorsport waste fire coil, 60-2 VR trigger. One of the cars did it first with 1.2.20 firmware but continued doing it after upgrading to 1.2.31. The problem manifests itself by leaving one or more injectors on when the ignition is turned on.

Car1 will NOT do it when tested on the bench, or when the prime pulse is not used. This has been a successful workaround. It will also NOT do it when the trigger sensor is disconnected, which probably explain why it doesn't do it on the bench. An injector output is used for the fuel pump relay.

Car2 is a Volvo 240.

The problem doesn't occur when the injectors are not connected when the ignition is turned on. But when the injectors are connected during powerup they will get stuck in an on position.

This car also leaves the fuel pump on forever when the problem occurs. The fuel pump relay is driven by an ignition output on this car. Removing the prime pulse as a workaround is not tested on this car yet. The tune is VERY crude as it was switched over to alpha-N minutes before ending the days tuning.

Possible software issue:

Many cars have some kind of noise during initial powerup. Something in the noise profile on these cars cause the firmware to hang during the prime pulse.

Possible hardware issue:

When all the injectors turn off at the same time after the prime pulse they cause an overvoltage spike resulting in a reset. I have obviously made sure that a good flyback connection is made.

How to test this:

Trigger setup - sounds like VR signal noise (=> fuelpump on; might not explain injout though ) I agree and I will measure the noise levels when it happens, but both cars only have pump run-on when the injectors are stuck. As the idle screw on one car came loose I also know that it does not have pump run-on when it stalls.