Just curious if anyone has deleted their secondary air injection system. If you're catless it's pretty much worthless anyways and just taking up space & weight.

I saw these people sell blockoff plates here: http://store.gospecracing.com/boxste...entline-1.aspx

But was curious if anyone has personally done this on their Porsche and know which vacuum lines need to be re-routed & tied together.

I know the car can be coded for RoW vs US and it should prevent a CEL or obdII emission testing codes as with most cars. But was mainly curious about what needs to go where and what needs to be tied off / removed.

Below is a link of a SAI replacement I found via google for a NA 996:
http://p-car.com/996/diy/sai/mainpage.html



and the picture showing the 2000+ SAI diagram:




And another reference of the turbo system:





And finally, a more detail vacuum diagram of the adjoining systems:

 

Subscribed...tempted to do this when I drop engine for coolant pipes.

 

This has been done many times. Lots on good info over on 6speed. I would start with TimNYC he is a great resource.

 

I'm curious about this as well, especially since Brick is from Nashville which I understand is an OBDII compliant area and requires all readiness codes to be present(with maybe one being absent). In Austin, TX we have very similar emissions testing. If I could rid myself of secondary air I would be pretty happy.

 

Not sure but guess you need to:

Remove part 4 - valve for secundary air injection and plug the hole with a plate

Remove part 3 - electric switching valve for secundary air injection

Plug the vacuum line going to part 3

Cheap and fast way is leaving part 4 (as you can not access with engine installed) and plug the rubber hose

 

Ignoring the increase in emissions and possible violation of the emissions laws in your area, not sure what this would buy you or the car. The SAI is to warm up the converters quicker so the DME can switch to closed loop mode and more precisely fuel the engine.

All I see happening is the engine gets less precise fueling for a longer time after a cold start with the real possibility excess fuel is helping to wash oil from the cylinders during this time.

 

Both sets of O2 sensors are self-heated, engine being open/closed loop should not be affected from SAI being present or not. DME doesn't care if converters are hot/cold/working/not-working in regards to its own function. Only thing affected by the SAI delete/ extended catalytic warm-up is actual emissions and emissions CEL from a lost SAI signal...re-tuning/coding the DME fixes the CEL issue.

 

uh, what?

The converter temp is not taken into account for the closed loop transition because by the time your coolant temp is near the transition temp, your cats have been warm for at least a few minutes.

Not to mention, the SAI injects air into the exhaust port.

Removing it will not affect the open to closed loop transition.

 

While the sensors are heated the converters are not. They require exhaust gas processing to raise their temperature and to sustain their working temperature.

While the DME will go closed loop as soon as the sensors are working it will continue to fuel the engine in an attempt to get the sensor numbers from the #2 sensors that are used to monitor converter performance. This will almost certainly result in less ideal fueling of the engine for longer period of time compared to if the SAI had been left in service and functional.

I still fail to see what benefit there is to removing the SAI.

 

That is not what I have observed. The DME goes closed loop concurrent with the SAI shutting down. Coolant temperature has not climbed hardly at all. The converters (and sensors) are hot enough to work.

The SAI does inject air into the exhaust port. It does this to provide extra air to allow the unburned fuel courtesy of an overly rich mixture to burn in the converters to help warm them and get them processing exhaust gases properly so the DME can then lean the mixture out to the point the engine produces exhaust gases that are most thoroughly processed by the now hot and functioning converters.

 

That would be unlike any care I've ever seen. Most vehicles go to closed loop between 130-150 degrees of coolant temp.

The sai runs for maybe a minute. Leaning out a cold motor would cause it to stumble and run like crap.

do you have obd data showing otherwise.

 

cats on a turbo system are a restriction. removing the cats eliminates the need for the post o2 sensors. with a heavily modded car like mine theres no diverters but bov's no cats and a full 3" exhaust and a full standalone engine management system. theres no need at all for the sai so removing it removes weight and also eliminates a host of vacuum lines that can eventually have leaks.

while this isn't for everyone i know the op and why he is asking this. virtually every sensor and sai has been removed from the dme and engine on my car with a proefi installed in its place and theres no cel lights and i can also pass emissions. cali emissions? no but tn yes.

if your looking for a oem reason to eliminate this setup there isn't one. from a performance view its simply not needed

 

+1 Quad and 32
Less vacuum lines the better.
Secondary O2's do nothing in regards to fueling/engine management, they are there only for emission 'sniffing' purposes, my car has secondary O2 extenders to avoid CEL from sport cats...
Datalog's would provide proper info into when the car truly goes closed loop, very likely its a timed event(pumping air into the exhaust tract once in closed loop would cause the primary o2's to read lean and richen the mixture incorrectly) for both SAI and open loop to cancel at the same time, if indeed they do coincide at same time.
Regards,
Rob