COD

[Welly]

No not Call of Duty but Cylinder-on-Demand from Audi 4-cylinder petrol engines!

My Sister rocked up in a new leased A1 with a 1.4 TSi and said she was struggling to get used to the gears when she put her foot down, it's a 6-speed Manual

A bit a Welly investigative work showed up this 'ere 4-pot actually cruises along on TWO Cylinders normally until more power is required and the other two wake up this is what she was experiencing; that kinda boost in effort, I think it puts out 150bhp.

Here's how it works, it actually removes the valving when not required:
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What could possibly go wrong?

[KozmoNaut]

What could possibly go wrong?

Literally everything.

It's been used on some V8s for a while though, and from what I hear they've been reliable. So who knows, but it is a VAG product, so it'll probably fail catastrophically 5 minutes after the warranty is up. The smaller 3-cylinder TSI engines are known for munching their timing chains.

[steve_earwig]

There was a meantion of the V8s on Autoshite a while back, apparently they run the cylinder banks individually, first one then the other, and they can run without coolant in them doing this. Why on earth that would be a feature is anyone's guess

So, ok, it turns the valves off, what does it do with the compression? Does it go into the inlet or exhaust? I seem to recall, in the dim and distant past, there were blowers run by using the compression of one cylinder which was run as a compressor.

I dunno, the piston is still going up and down so I presume it'll still wear the same, maybe engines warping due to uneven heating?

[Welly]

I thought the valves were held open equally, no compression, so all you get is 340cc's worth of 'air' which goes up a breather somewhere.

[steve_earwig]

Having a better look at the vid (i.e. not on the mobile) it looks like the solenoids push the cams out of the way so the valves no longer open, so the engine is fighting the compression of those two cylinders twice a revolution. Those solenoids look kind of fragile too, I bet they won't be cheap to replace

[Welly]

Those solenoids look kind of fragile too, I bet they won't be cheap to replace

Yeah those locating pins look the kind of stuff that wears and become rattly and I'll bet you a virtual pound that if you do not have it serviced by Audi using MEGA EXPENSIVE special* oil or miss a service interval by either 0.01 miles or 1 nanosecond then the whole Warranty is void.

[Doggy]

A1 TSi you say?
D'ya think a rear view mirror full of 406 would hasten the answer to your reliability questions?

[FarmerPug]

Cadillac had a system like this back in the 80s
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[Captain Jack]

Oh Lord. Not sure which is worse, the Caddy or the A1.... With all the tech crap car manufacturers churn out these days, I am going to hang on to the 407 for as long as I practically can...

[Doggy]

Oh Lord. Not sure which is worse, the Caddy or the A1.... With all the tech crap car manufacturers churn out these days, I am going to hang on to the 407 for as long as I practically can...

Amen to that. I aim to keep the 406 forever, or maybe longer.