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Is the secondary air injection system really necessary?


phazed

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As title. Just wondering while I am assembling mine. Seems to be a lot of hardware that other cars haven’t got.

Will it pass an MOT without it?

I read somewhere that it was primarily for the yank market…

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It should do as the SAI is designed to clean up the exhaust during the warm up phase. The MOT is done on a fully warmed up car, so it should have no effect unless the removal is bodged and leaves an unplugged air line somewhere.

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I wonder if I remove the system now whether error codes would come up. If so, what or who could remove them?

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My understanding is that it's a "compliance for type approval" device, not a "testable on individual cars" thing. But - given it's one of the sources of CEL I would expect if a car with it simply had it disconnected or was faulty then a CEL results - and as far as I know that's an MOT failure isn't it?

 

 

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Quite. It is all assembled atm so will leave until it plays up.

Will progress tomorrow.

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One of my 996 cars has the little black pump or had it. I removed it and put a bung in the pipe to prevent any vac leaks. No errors or warnings. Car drives fine without. 

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1 hour ago, ATM said:

One of my 996 cars has the little black pump or had it. I removed it and put a bung in the pipe to prevent any vac leaks. No errors or warnings. Car drives fine without. 

Yes, the Yanks delete it then flash to the Euro tune I think. If you already have the tune it could be easy.

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All good, but.... recently was asked to help out a local TIPEC guy who has 2 996 Ruf Turbo's - as an aside - him and his wife are total petrol heads - he has 2 kids - one Ruf has the rear seats in - so thats her car for her and the kids - his has the rears removed - and was his MUM's car when he was a kid - she used to do the school run in it.!

Anyway - his car threw a CEL - and when I scanned it - it was secondary air system related - he said "oh again - I just had that mapped out on my daily BMW M2" - so, that car, with the RUF map on the custom DME threw a CEL - if we can get round it with a rubber bung - thats great - but I am surprised ( and I bow to real first hand experience from @ATM on this ) if its that simple - I would expect it would be a "mapped out" custom ECU map.

Would love to know if you can just remove it and the ECU remains happy 

 

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On 4/23/2024 at 9:19 PM, phazed said:

Just unplug the feed to the air pump?

Yes

 

The 12v stuff.  I assume then it wont do anything.  Assume also this will not cause an air / vac leak because you dont want an air / vac leak.

 

I removed the whole thing,  But I am suggesting if not brave enough for that you could try just unplugging the 12v stuff from it.

 

Make sense?

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I agree with others. I'm pretty sure it was fitted for the American market and was designed to pump air into the exhaust when the engine was cold and running a very rich mixture to keep it going ..... "on full choke" as you might have said back in the day.

The theory was that the pumped air would combine with the unburnt hydrocarbons at this point to ensure that they were completely combusted and no "black smoke" would come out of the exhaust.

All our MOT emission tests are performed with the engine fully warm, so even if fitted, it wouldn't be operating.

A mate of mine had that system fitted to an old 1.8 turbo Passat and it drove him mad as the engine light would keep coming on, warning him of  a fault on something that wasn't needed and would cost a small fortune to replace the pump on no doubt.

 

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