Secondary Air Injection System fix and diagnostics

[neckarsulm]

For the past few months I'd get EML on and following code stored.

17831 - Secondary Air Injection System; Bank 1: Insufficient Flow
P1423 - 35-10 - - - Intermittent
17819 - Secondary Air Injection System; Bank 2: Insufficient Flow
P1411 - 35-10 - - - Intermittent

I'd clear and it'd come back every few cold starts.

Finally got time to look at it this week and stripped off a lot of the pipes etc at the back of the engine to get to the SAIS solenoid which is located on a plate tucked away under the EGT sensor plugs on the back of the inlet manifold.
I knew it wasn't the pump as the last owner had the EML on for the same reasons and the pump was replaced at great expense according to the bills.

The reason mine was playing up was because there is a very short piece of vacuum pipe (25mm) that connects the solenoid valve to the pipes that connect to the SAIS valves that let the pumped air into the cylinder banks when bacuum is applied to them by the solenoid valve.
It had gone brittle and formed an S shape blocking flow.

Once replaced I used Basic Settings blocks 77 and 78 on VAG COM which run a test to measure the flow of the SAIS system and report back 'System OK' or 'System NOT OK' , thankfully I got the former!

Because my RS4 has the later AZR engine code I gather it's more likely to put the EML on if there is a fault with SAIS than with the ASZ engine.

Thought I'd post this as it's quite a common fault.

Also you can run an output test on the SAIS solenoid valve to see if it clicks away but this doesn't seem to produce suction through the vac pipes as the engine is off, however the basic settings procedure run with the engine running does so you can pop the vac pipes off the air valves on each bank easily and see if there is suction there when the air pump is running. If not and the solenoid is clicking away in the output test, it's likely to be duff vac pipe.

[HEKTOR]

You would know if your secondary air pump had gone as it makes a horrible noise, mine is making a racket when started from cold. Is it an easy job to change the pump?

[lushman]

Did the pump start playing up again on a cold start Hektor? If it has at least you have a replacement that you nearly forgot.
To replace all you have to do is remove the Y pipe and there are 3 10mm nuts to loosen and the leads and that should be it

Paul

[neckarsulm]

If it's completely packed up it makes no noise at all!

Compared to the 25mm of vac pipe, swapping pump is dead easy.
There are 2 x 5mm (I think) allen bolts at the top holding it to the inlet manifold and one 10mm nut on the right handside of the pump (as you stand looking at it) which is easy to miss as loads of pipes obscure it.
You don't need to undo the 3 longer allen bolts that hold the pump to the retaining frame though it might make it easier to get it out as it's a very tight fit.
Undo the bolts, unplug the 2 pin power supply, unscrew the jubilee clip holding the output pipe on to it and lift out.
They come apart easily so can maybe be cleaned and lubed up.

Many people have removed the SAIS (N249 delete??) but it really needs a chip tuner to delete it all from the ECU too and seeing as the last owner of mine had spent so much on a pump, it seemed silly to junk it.

[HEKTOR]

Did the pump start playing up again on a cold start Hektor? If it has at least you have a replacement that you nearly forgot.
To replace all you have to do is remove the Y pipe and there are 3 10mm nuts to loosen and the leads and that should be it

Paul

Yeah it started yesterday and i nearly sh*t myself when i heard the noise, the whine from the fuel pump has come back aswell and the clutch bearing have started to go but still loving it. I think i'll just hold off till i scrape some cash together and get the boys at unit 20 to sort it. Hows things going with the extension?

[HEKTOR]

If it's completely packed up it makes no noise at all!

Compared to the 25mm of vac pipe, swapping pump is dead easy.
There are 2 x 5mm (I think) allen bolts at the top holding it to the inlet manifold and one 10mm nut on the right handside of the pump (as you stand looking at it) which is easy to miss as loads of pipes obscure it.
You don't need to undo the 3 longer allen bolts that hold the pump to the retaining frame though it might make it easier to get it out as it's a very tight fit.
Undo the bolts, unplug the 2 pin power supply, unscrew the jubilee clip holding the output pipe on to it and lift out.
They come apart easily so can maybe be cleaned and lubed up.

Many people have removed the SAIS (N249 delete??) but it really needs a chip tuner to delete it all from the ECU too and seeing as the last owner of mine had spent so much on a pump, it seemed silly to junk it.

Cheers for the run down, im fairly hopeless at that stuff but i might give it a try with my mate that works for audi watching over me.

[neckarsulm]

It's a very easy job a reasonably competent DIYer
Hardest bit is standing up straight after bending over for so long, Doug and Grizz must have good chiropractors

[Nige_RS4]

Hecktor, it might easier and cheaper to get Grizz to remove the secondary injection alltogether - you don't need it

[HEKTOR]

It's a very easy job a reasonably competent DIYer
Hardest bit is standing up straight after bending over for so long, Doug and Grizz must have good chiropractors

I'll give it a try i think, i dont think i can brake anything else while changing it.

lol i'll bet they do.

[HEKTOR]

Hecktor, it might easier and cheaper to get Grizz to remove the secondary injection alltogether - you don't need it

I already have the pump as i bought the car knowing it had a slight problem with this, and i was givin the pump by the previous owner so im not out of pocket for the pump. Does it make any difference to remove the pump etc completly?

[neckarsulm]

Removed properly with ECU tweaked accordingly it's fine but I like to keep mine as it left the factory..

[HEKTOR]

Im with you neckarsulm, im sure audi put it there for a reason. i think im going to tackle the job tommorrow so i will post up how i get on. cheers for the advice and wish me good luck lol

[HEKTOR]

Just had a try at changing the pump, it is impossible to get the last nut out from the back of the pump, my hands are cut to shreds! and to top ot off i managed to brake a small plastic pipe that comes from the y pipe into a small black valve type thing next to the air pump, and i have noticed that some cowboy has not connected an oil pipe which appears to go into the head behind the black plastic cover onto of the cams!!!

so just to round things up the car is in bits i have broke something and there is a pipe disconnected that shouldnt be and i have no idea how to fix this thing, any offers to help would be great since the car cant move now lol

i knew i should have left this to a pro!!!!!

[HEKTOR]

the part i broke is 078129101a does anyone know what this is and where to get it?

[HEKTOR]

does the inside of the y pipe become oily over time?