Intermittent Burning Smell on 2016 Transit Custom

[Sheeplady]

Several times today, I have noticed a very strong, acrid burning smell coming from the 66 plate transit custom that I drive.
It only occurs for a maximum of a minute, then the smell completely disappears. Starts of with the van smelling rather ‘warm’ whilst driving, give it 10 secs, an electrical burning sort of smells then appears, which gradually gets stronger, to the point you think the van’s about to set fire, then it just disappears. Seems like it’s coming from the engine bay as you can’t smell it when the windows are up. Oil and coolant all fine. Can’t see any leaks or signs that there’s something leaking and burning off. Only occurs when driving, particularly around 30 minutes of starting a journey. Any ideas of where to start looking would be appreciated. Also temp gauge is reading fine.

TIA

[Altransit]

I'm not sure how you would check, but it's possible that it's just the DPF regenerating (cleaning itself)

When this happens, usually after the engine is up to heat, and revving fairly fast, it loads the electrical circuits, and the engine runs hotter (and slightly rougher) for several minutes.