Tips for Beamng export

Hi all,
I have created a car to export to Beamng. Beyond 4000rpm or so the engine locks up, but this does not show up in testing in Automation. I thought it might be the conrods, based on the fact that BMW’s V10 did exactly the same, but changing these has made no difference. What else could the problem be and how do I fix it?

The problem has now fixed itself. Don’t know why but it is working now.