Hi Keith

Wasn't there a Landrover diesel variant back in the 1980's that utilised a mechanical throttle plate, that was used for the sole purpose of creating a degree of vacuum, for brake survo operation.

Mark

Interesting & informative as usual.

It is worth mentioning also that the throttle plate on some manufacturer systems, is operated at engine shut down, in order to starve or strangle intake & in doing so, the engine will come to a halt more smoothly. With a reduced amount of air to inhale & compress, the pistons rise on the compression stroke with less resistance. This makes for a much smoother engine shut down.

Keith

I think we could debate the point about "no depression", but it is clear that a system without a throttle plate mechanism, will have negligable vacuum (depression) in the inlet manifold. My understsanding is that the throttle flap will purge the EGR tract more effectively than the older style system, where intake flow alone is responsible for drawing in the inert EGR.

Good thread!

Cheers

Dave