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Discussion Starter · #1 ·
If the EGR diaphragm gets holed (and with miles it will), the drivability symptoms are shunting at cruise. No problems idling, or under load. Only when the engine is at steady throttle. Feels like plug failure.

The quick cure is to block off the vac pipe running to it from the inlet manifold. Leave ebrything else as is. No more problems. Suggest you leave things like this - the only "problem" caused by this is fix is a slight rise in NoX from the exhaust when cruising. Depends how you feel about this...
 

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Discussion Starter · #3 ·
Wrong.

The diaphragm sits between fresh air and engine vac - that's how it works. Have a proper look.

When the diaphragm splits, air enters the inlet manifold every time the solenoid operates - i.e. at cruise.
 

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Omega Tank Commander
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Granted it would give a small air leak but, pretty minimal and its a rare failure.

If the diaphragm is split then the vaccum will not be able to open the valve and let exhaust gases in and hence the valve always stays shut. This is good from a driveability point of view as the EGR is no longer operating.

What isn't is if the valve sticks open and gases always get in....

Granted it would give a small air leak but, pretty minimal and its a rare failure.
 

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Discussion Starter · #5 ·
Failure is common with mileage, and since the diaphragm is exposed to full inlet depression, the effect on running is dramatic. Try driving yours with the pipe disconnected...... not for too long though - holed pistons aren't funny.
 

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Omega Tank Commander
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Failure is common with mileage, and since the diaphragm is exposed to full inlet depression, the effect on running is dramatic. Try driving yours with the pipe disconnected...... not for too long though - holed pistons aren't funny.

Think you might be out of your depth......

Its not a common failure, I have seen a few stick open but none with holed diaphragms.

On a V6 the EGR is NOT vaccum operated so thats a no. no but, the closest equivalent is to have one of the small vaccum hoses off and they make pretty much diddly squat difference (except the heater or multiram wont work because the vaccum has been removed from them)

As for holing a piston, it wont, the mixture is under closed loop control so it wont run lean.....
 

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Discussion Starter · #7 ·
Think I sell and fit the vac operated ones for X20 and X18s like shelling peas. Perhaps I should have made my background a little clearer...

They are prone to age related diaphragm problems...

Simtec cannot compensate for a large air leak into the system. The Lambda sensor runs on "go rich" all the time at cruise - and you haven't seen the results of that, obviously.
 

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Think I sell and fit the vac operated ones for X20 and X18s like shelling peas. Perhaps I should have made my background a little clearer...

They are prone to age related diaphragm problems...

Simtec cannot compensate for a large air leak into the system. The Lambda sensor runs on "go rich" all the time at cruise - and you haven't seen the results of that, obviously.



I think that would be a good idea, people are only trying to help but if you do know different then maybe a detailed explanation would suffice.
 
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