SAI / 249 Bypass - guide

**noone** · 15-09-2012, 11:19 AM

There are a few threads on this, but thought I'd put something together to explain.

Going to need to do this with borrowed photos, etc.

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What is it? Removal of the Secondry Air system on the Polo GTI (may suit other vehicles).

Why: The pump / combi valve is prone to failiure and the Vac system is not required (IMO) after the SAI is removed:
The Vac system includes N249 control which allows the ECU to modify the boost slightly
The 249 also regulates the VAC to the diverter valve, for tuned Polos, some have found more consistant boost or better diverter action (noise) from bypassing.

Downside: As I understand (so not necessarily correct) The SAI system is designed to reduce emissions by heating up the CAT faster

What is required:

For my car (should suit Polo 9N3's as a whole, but don't quote me on that) best results have been experinced with the following parts:
2 x IE Oval shaped Resistor Plug
1 x IE Resistor (they cost very little I'd get 2, just in case)
IE SAI blanking plate There are a few places to get these

As postage is significant, group buys are prob the best way to go.

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Asside from the above, you are likely to need a few bits and peices that can be locally sourced or may be in your stock of car crap;
- Top up of G12++ coolant as some is lost in the process (volume TBC based on Jmac's help of how not to loose a lot)
- 1 meter of vac line (as its cheap, get more). I think 3mm or 4mm is what suits, you can cut off 1cm from your existing vac lines and take it in to a auto store to see what is suitable. You are better off with forcing on something to small rather than larger, looser fitting piping.
- A few decent small cable ties
- Basic Hex / security bit set and tools (I have a mini ratchet set I use frequently).

Overview;
So again, I have to apologise for borrowing someone elses photo for this. If I've used a photo of yours and you don't want me to, please let me know and I'll take it down.

Once the engine cover is off, your engine looks something like this;

1 The SAI Sensor electrical socket - use one resistor plug
2 The VAC resoervoir system, junk and bracket (held on with 3 bolts, small socket set to remove)
3 N249 system and electrical connection - bypass this
4 Diverter Valve - connect vac line to manifold
5 Combi Valve - this is to be removed when the bolts attaching it to the engine are removed

A few reference photos from when i did this originally (threw codes, so put it back)

the removed parts:

Small blanking plate I cut from plastic and taped over the stock airbox hole

Procedure:

Remove the vac lines:
- From the intake manifold to the VAC / 249 System
- From the N249 to the dverter
- From the vac system to the combi valve

- Run a new vac line direct from the manifold to the diverter. you should also have another line from the mani to the FPR still.

Disconnect the 2 electrical connections (Vac at #1, N249 at #3).

Remove the 3 bolts that mount the SAI system onto the top of the engine block.

The SAI system should lift loose, ready for storage / bin.
Use the 2 oval resistors in the SAI and N249 electrical plugs.

Thats part 1 done.

Part 2 I'll try and get some more photos for.

Disconnect the 2 flex hoses that run to the combi valve and Airbox.
Plug the airbox hole (I cut a circle from thick plastic and used tape and a cable tie to keep in place)
The SAI pump is located in front of the intake mainfold. The bracket that the dipstick clips into holds the SAI pump in place.

Disconnect the SAI pump electrical plug and tock airbox pipe / PD160.

The pump is held in by 3 bolts, one where the dipstick mounts and 2 through the top of the mainfold. they form a triangle.

Remove these 3 bolts, whilst supporting the pump. The bolt nearest the dipstick mounts a seperate bracket on, mind you don't drop this.

The pump should lift out towards the battery.

Use the bare resistor in the end of the pump's electrical connection (I again used electrical tape and a cable tie to secure).

The last part is removing the Combi valve, this bit requires good access to the side of the engine, removing the flex pipes for the pump has helped with access / visibility.

In order to access the 3 bolts at the bottom of the combi, a coolant pipe (well, 3 that join at the side of the block) needs to be removed. If you remove the coolant pipes, you loose a large amount of coolant. I'm hoping to be able to clamp the 3 pipes around this and not loose all my fluids.

**Mr Blobby** · 18-09-2012, 03:52 AM

Very interested in this, and there are no disadvantages other than not warming the cat up as quickly?
Just wondering what do you guys here use to check your engine codes? Because on the other thread about the SAI delete some of you were saying how you logged your boost and things like that, I can borrow my friends VAG reader for codes but thats all it does and i want to do more than just read codes...

**noone** · 18-09-2012, 08:49 AM

The big disadvantage IMO is possibly throwing a code. I dont like having a CEL warning on my dash. This solution seems to work.

Once a few other bits arrive (need allan key style bits for easier access), I'll finish it off.

**dubstar** · 18-09-2012, 10:19 AM

Can you just remove the SAI and Combi Valve? Leaving the N249 in place?

**VWindahouse** · 18-09-2012, 10:49 AM

Originally Posted by noone

The big disadvantage IMO is possibly throwing a code. I dont like having a CEL warning on my dash. This solution seems to work.

Once a few other bits arrive (need allan key style bits for easier access), I'll finish it off.

Hey mate in regards to the CEL, I remember now what I did to erase the issue once and for all. I threw a code at about 500kms after the delete because I stupidly bought 1 oval and 1 square resistor so had to go to Jaycar to get one of the bare resistors (like the one IE sell for the SAI pump) to go on while I waited for a another round one.

He didn't have a 330 ohm resister so he piggybacked 2 smaller ones which gave a total resistance of about 400 ohms from memory (or maybe a little less) anyway it seems 330 is too little and will through a code. But a bit more resistance does the trick and I have not had a CEL for over 15,000kms

**VWindahouse** · 18-09-2012, 10:50 AM

PS great write up!

**s4mmie** · 18-09-2012, 03:14 PM

If you want to get rid of the vac reservoir and N249 to free up a little space in between doing the full delete you can.
All I've got on top now is the N112 still connected, waiting on INA for my flipping resistors!