SAI and N249 Removal

[vwthunder]

I have read a bit of info on the Vortex about this, has anyone done the Secondary Air Injection System and the N249 Removal on their 1.8T

Tips, hints, things to stay away from, Yay or Nay ??

Engine bays look so much cleaner without them

Any info would be good on this

Cheers

[noone]

The SAI is for emissions from my understanding and the N249 helps regulate the diverter valve.

I don't think there is a lot to it, but you are removing some control from the engine management designed to protect the engine.

[vwthunder]

I have read people say that with the N249 removed that their cars are boosting better, dont know if this is true or not

Anyway guessing no one has done it here yet

For anyone interested there is 88 pages here, happy reading

http://forums.vwvortex.com/showthread.php?3111538-DIY-Cleaning-up-Engine-bay...Removing-SAI-N249-PCV-EVAP

[noone]

Have a look at Polo UK site, many common things there that dont happen here.

I bypassed my N249 for a while, could not tell the difference so I reconnected it as it did not make sense to leave disconnected if I could not feel any difference.

Be aware that info on Vortex may relate to different ECU's, thus really a different result / effect. Have not read that thread.

[Plautos]

I thought in remove that thing from my car... but I decided not to.
It is a good fail safe.

[Plautos]

TRUE! (in my situation)

The car is boosting faster and I’m feeling a better turbo response.
The BOV’s sound changed, it is more “dry”.
What I did...
I pulled from the intake, the hose that feed vacuum to the N249 and EGR system and I connected the BOV in its place.
I’m going to remove the entire system and probably the SAI too.

I have read people say that with the N249 removed that their cars are boosting better, dont know if this is true or not

Anyway guessing no one has done it here yet

For anyone interested there is 88 pages here, happy reading


DIY: Cleaning up Engine bay...Removing SAI, N249, PCV, EVAP

[noone]

So now I'm intrigued with this again...

Removing or bypassing the N249 removes the Cars ability to use the vac system to bleed boost. Does this mean you can remove the whole vac system or are there other components that require this?

With the SAI bypass, is this going to make the car unroadworthy for emissions? I don't like the SAI system as it looks pretty flimsy and has lots of leak potential, but will this screw with the AFR on startup? Could that cause issues? Looks like just the little blanking plate and basic parts are required...

[Plautos]

The N249 not only bleed boost, it make the boost smooth. I don’t know what VW engineers tried to achieve with this system, first I thought it was a failsafe, but now it look just like another gizmo. I notice (in my situation) the turbo boosting 500rpm earlier, that’s a lot!

I’m pretty sure it is possible to remove the entire system without affecting other components. I start the engine with the solenoids disconnected and I didn’t have an engine light. In the worst case scenario a transistor will be needed.

The SAI only work when the catalyst and sensors are heating up. After that, it becomes dead weight. I drove the car almost 100km with the bypass and I had no problems. I don’t think any problem can be generated with its removal.

I’m thinking in say goodbye to the N75 also. Just connect the WG to the intake manifold and be happy.

So now I'm intrigued with this again...

Removing or bypassing the N249 removes the Cars ability to use the vac system to bleed boost. Does this mean you can remove the whole vac system or are there other components that require this?

With the SAI bypass, is this going to make the car unroadworthy for emissions? I don't like the SAI system as it looks pretty flimsy and has lots of leak potential, but will this screw with the AFR on startup? Could that cause issues? Looks like just the little blanking plate and basic parts are required...

[noone]

The N249 not only bleed boost, it make the boost smooth. I don’t know what VW engineers tried to achieve with this system, first I thought it was a failsafe, but now it look just like another gizmo. I notice (in my situation) the turbo boosting 500rpm earlier, thats a lot!

I’m pretty sure it is possible to remove the entire system without affecting other components. I start the engine with the solenoids disconnected and I didn’t have an engine light. In the worst case scenario a transistor will be needed.

The SAI only work when the catalyst and sensors are heating up. After that, it becomes dead weight. I drove the car almost 100km with the bypass and I had no problems. I don’t think any problem can be generated with its removal.

I’m thinking in say goodbye to the N75 also. Just connect the WG to the intake manifold and be happy.

I'm not sure about removing the SAI as the return air is expected on startup, surely this would mess with the AFR for the first 1 min?

As for bypassing the N75, unless you are using a MBC, how would you control the wastegate?

I'm not sure if these would work too well for normal driving, as your car is set up for track use, maybe a little different?

[vwthunder]

As for bypassing the N75, unless you are using a MBC, how would you control the wastegate?

Yeah that is what i was thinking

I have a manual boost controller sitting here, will put it in when i have time and hopefully see a spike over 17.6psi, which is what i am getting according to logging

[Plautos]

In a fuel injected car, there are some moments the emissions are disregarded. Normally is the warming up period and in some cases when you give full throttle. The SAI pump and EGR are just gizmos to make the car greener.

You have to remember the lambda sensors only work when they are hot and they are responsible to help the engine with AFR.

The N75 is one other failsafe gizmo. It works blocking the pressurized air to the WG, therefore we have boost. If you disconnect it, the air will pass through it opening the WG.

What I will do. I will recalibrate the WG. I will tighten it more to open after 1,4bar.
One other option it to use a MBC. It will work fine too.

I'm not sure about removing the SAI as the return air is expected on startup, surely this would mess with the AFR for the first 1 min?

As for bypassing the N75, unless you are using a MBC, how would you control the wastegate?

I'm not sure if these would work too well for normal driving, as your car is set up for track use, maybe a little different?

Yeah that is what i was thinking

I have a manual boost controller sitting here, will put it in when i have time and hopefully see a spike over 17.6psi, which is what i am getting according to logging

[noone]

All threads I've read on MBC's for the 1.8T's report partial throttle issues with MBC. I drive in too much traffic to want the hassle of throttle abnormalities...

Can someone help me understand how the vacuum works off the manifold? Is this vacuum consistent or does it fluctuate with the revs?

[h100vw]

All threads I've read on MBC's for the 1.8T's report partial throttle issues with MBC. I drive in too much traffic to want the hassle of throttle abnormalities...

Can someone help me understand how the vacuum works off the manifold? Is this vacuum consistent or does it fluctuate with the revs?

Have a think about how an engine fills it's cylinders. Suck, squeeze, bang, blow. You get vacuum when the pistons are going down the bore with the inlet valve open.

On a turbo car, this would be true during off boost conditions and very small throttle openings. When you open the throttle, boost rises and you have positive pressure in the manifold.

When you close the throttle during a gear change or over-run, there will be positive pressure between the turbo and throttle body, which gets vented back to the inlet. In the inlet manifold, there will be a vacuum as the pistons suck against the butterfly.

If you have a boost gauge you can see this easily.

Gavin

[Plautos]

I disconnected all solenoids (n249, n75 and n112) and the SAI pump.

I’m using a MBC! I remembered I had one!

I've got frustrated, the electronic throttle hold the engine. I will need to use transistors.

On the other hand I finally can see the engine.

[Plautos]

I connected the solenoids and give one other shoot.

The results were impressive. With 1,3bar now I have more torque then before.