Exhaust valves

[Fez]

There are two software H139 & H239 they came about a year apart. Avoid H139 means our car will not remember dynamic mode when ignition turn off.. H239 reduces noise even further by using electronic wizardry... hence my 400 has no updates after H139..

[Mightyhunter]

Is there a way to check what software updates have been done? I’m convinced my 400 has been neutered (doesn’t remember Dynamic mode on start up) but my dealership are adamant that it’s not had either of the software updates?

[@299Peter]

A pointer, I’ve instructed my local main JLR dealer to put a note on my vehicles service record that instructs them to ask me first before any software updates are installed - I absolutely do not want my V6S noise neutered at all!!

[S1jor]

The valves don’t seem to be moving at all,
I think from what I have read, with the engine off the valves are open (loud), upon start up the valves are open , until the vacuum closes them?? Is that correct??
I’ve been under the car and had someone start it, and they don’t seem to move

I have another look at the vacuum lines and make sure there all connected

[cj10jeeper]

Given you know the valves work smoothly, then I would take the pipe off one side and see if it is creating a suction. That will get you one step closer to deciding if it’s a mechanical (vacuum) or electrical/switching issue

[RPSN]

Given you know the valves work smoothly, then I would take the pipe off one side and see if it is creating a suction. That will get you one step closer to deciding if it’s a mechanical (vacuum) or electrical/switching issue

I would also think that the active exhaust vacuum pipes suck rather than blow air but this early F-Type ‘Active Exhaust Vacuum Control Diagram’ (which is prior to the vacuum conversion) seems to show the air flow going into the exhaust valves?

This is what it says about the ‘Air flow check valve’ and ‘Air flow restrictor’ shown on the diagram.....

“In the pipes between the solenoid valve and the exhaust valves, a restrictor is installed in parallel with a check valve. The restrictor slows the flow of air through the pipes, to damp the opening of the exhaust valves. The check valve ensures that air flows only through the restrictor when the exhaust valves are opened, but allows the restrictor to be by-passed when the exhaust valves are closed, to give an undamped closing movement.”

I suppose the only way to be sure is to remove the vacuum pipe from a working exhaust valve to check if it’s sucking or blowing air?

[cj10jeeper]

Given you know the valves work smoothly, then I would take the pipe off one side and see if it is creating a suction. That will get you one step closer to deciding if it’s a mechanical (vacuum) or electrical/switching issue

I would also think that the active exhaust vacuum pipes suck rather than blow air but this early F-Type ‘Active Exhaust Vacuum Control Diagram’ (which is prior to the vacuum conversion) seems to show the air flow going into the exhaust valves?

It's 100% certain to be a vacuum. Given the conversion is to take a feed from the inlet manifold which has a vacuum in it, not a positive pressure

[RPSN]

Given you know the valves work smoothly, then I would take the pipe off one side and see if it is creating a suction. That will get you one step closer to deciding if it’s a mechanical (vacuum) or electrical/switching issue

I would also think that the active exhaust vacuum pipes suck rather than blow air but this early F-Type ‘Active Exhaust Vacuum Control Diagram’ (which is prior to the vacuum conversion) seems to show the air flow going into the exhaust valves?

It's 100% certain to be a vacuum. Given the conversion is to take a feed from the inlet manifold which has a vacuum in it, not a positive pressure

I would think so.

However, the earlier set-up was also operated by a vacuum as shown in the diagram I posted, which seems to show the air flow going into the exhaust valves?

To be 100% certain, the vacuum pipe that connects directly to the exhaust valves would need to be removed and checked.

[Jaguandy]

The orientation of the check valve in the diagram would result in rapid opening and slow closing of the valves.

[cj10jeeper]

I would also think that the active exhaust vacuum pipes suck rather than blow air but this early F-Type ‘Active Exhaust Vacuum Control Diagram’ (which is prior to the vacuum conversion) seems to show the air flow going into the exhaust valves?

It's 100% certain to be a vacuum. Given the conversion is to take a feed from the inlet manifold which has a vacuum in it, not a positive pressure

I would think so.

However, the earlier set-up was also operated by a vacuum as shown in the diagram I posted, which seems to show the air flow going into the exhaust valves?

To be 100% certain, the vacuum pipe that connects directly to the exhaust valves would need to be removed and checked.

My read of that diagram is clear
The vacuum pump creates a partial vacuum and that is stored in the reservoir. The suction applied to the exhaust valves goes through a damper, which will be there to smooth the process so the valves open progressively and not in a jerk motion as the pump works. To close the valves air enters the pipework through a filter and valve which is undamped and thus allows the valves to close rapidly. If not then when closing you'd have to wait ages for the vacuum to decay by leakage. Air flow is bi directional in the pipe depending upon the desire to open or close.

Later cars simply eliminated the vacuum pump and reservoir [noisy and unreliable] with a straight vacuum from the inlet manifold