Understanding The Secondary Air Injection System

[dave_6]

Ok so like many people I started off getting the incorrect flow code, bringing up the EML light, car also feels slightly less impressive when the codes noticed aswell, still has the power but its hard to explain. It’s like it holds back slightly


Anyway, my problems started when my N112 bracket broke and the N112 melted at the back of the engine!


Ended up removing the whole SAI system and used a blanking plate, and resistors. Still got the incorrect flow code every few days though.
Not ideal when I want to sell the car in a month.


Anyway I got myself a replacement N112 and spent Saturday morning putting everything back together, I’d checked the pump still worked before hand so I knew that was fine.


Put it all back together and cleared the code and started the car. On came the SAI pump for about a minute in time. The revs then drop after 2 minutes don’t they when the engines cold. Everything fine, no faults. Turned the engine off.


Drove the car later on Saturday and the pump came on when I started the car, Saturday was very hot by the way. No faults.


Didn’t use the car Sunday, this morning at 8am, trip computer showing its 17 degrees already.

Started the car and the pump didn’t come on….? Thought it was a bit odd, I’ll have to check the plugs still on fine to the pump but pretty sure it will be


Anyway didn’t get any fault codes this morning even without the pump coming on.



Is there a temperature that the pump comes on at, or doesn’t need to come on at? I know that if you drive the car and stop for half an hour and then drive again, the 2nd time of starting the car the pump wont come on as things are still heated up

But surely this morning the pump should have came on, even at 17 degrees the cat still would have been cold wouldn’t it?



Just trying to understand things in a little more detail but the first thing I’ll check later is that the pumps still all plugged in ok



Cheers
Dave

 

[mr_D]

why dont you use the resistors. can even put one on the pump and that should keep it off

 

[dave_6]

Mate, I've tried resistors and like other people I've still had the code come back

some seem to get away with it others don't

the incorrect flow code doesnt seem to be able to be solved just by resistors

 

[mr_D]

thats strange. i know loads have been ok with it. if not then their aint much you can do mate. as stated you have the plate there and all other pipes blocked. everything discounnected and you have tried resistors.

but what resistor were you trying?

 

[Damoegan]

I have ripped out the SAI and get the code every other day too.

 

[redcupraboy]

Same here pretty much I get the code every few days with the incorrect flow code for removing SAI and fitting a Forge blanking plate, its ok though I just clear it with my scangauge ii.

 

[dave_6]

I used 10W 330R resistors, I know the resistor in the N112 plug was working fine at the time because with the N112 plug not connected to anything I got a fault code in vagcom saying there was an imcomplete circuit, fitting a resistor solved it - still got the incorrect flow code though


Since fitting the SAI back with a new N112 and checking all pipes had no leaks I've not had an EML back yet.

This morning the pump didnt come on but I didnt get the EML light.... and after work today sure enough the pump did come on for the 65 seconds and so far no EML light

I'll see how it goes over the next few days and see how the pump behaves


I wonder what tells the pump to come on or not, surely its a temp sensor somewhere to tell the car if it needs to come on for a cold start, or if the car is already warm enough

Maybe a coolant sensor tells the pump to come on at start up if the coolant temp is under a certain level..? i dont know!



This thread seems to be very interesting.. http://www.myvwlemon.com/ubb/Forum2/HTML/000518.html

suggests the combi valve is often the original problem
When combi valves go bad, they leak exhaust and condensation into the pump, which
ruins it. The combi valve is a one way vacuum operated valve, if water gets in the
pump, the hose between the air filter box and pump is broke or the combi
valve is leaking...

remember what the pump is doing . It is pumping/ blowing air into the exaust manifold. This air is as moist as the air outside and so it can easily over time destroy a cheap pump.I have a guess that in dry parts of the US they would have less problem with this .

another post on similar is here http://forums.vwvortex.com/zerothread?id=2332189&postid=25443239

 

[dave_6]

Still no EML light so far so at least thats something, this morning the pump didnt come on again, 19 degrees trip computer said.

And then like yesterday, after work and the pump did come on when I started it up, and the trip said 29 degrees

If the light does come back and the pump doesnt kick in then i'll probably try taking it apart and cleaning it up inside as much as possible! be interesting to see the state of it inside

 

[thewiizard]

Why not just reconnect the sensor

Seriously though, what's the actual benefit to removing the SAI and related gubbins?

 

[dave_6]

my sensors are all reconnected.....

Alot of people still get the incorrectflow code though and some remove the SAI system to tidy the engine bay, remove weight, get rid of the code etc

Unfortunately for some, the code still comes back even with the SAI removed

 

[thewiizard]

have you seen this;

http://wiki.ross-tech.com/index.php/16795/P0411/001041

16795/P0411/001041 - Secondary Air Injection System: Incorrect Flow Detected

Possible Solutions

* Check Fuel Pump Relay (J17)
* Check Hoses/Pipes to/between Components
* Check Secondary Air Injection Pump (V101)
* Check Secondary Air Injection Pump Relay (J299)
* Check Secondary Air Injection Solenoid Valve (N112)

found in http://www.seatcupra.net/forums/showthread.php?t=81279 ?