Secondary Air Injection

[MonroeS4]

I haven't been able to locate much info for this system. I have a pump which won't turn on shortly after having the turbos replaced. Pump is fine, I even replaced the bearings. Hot jump it runs great. 40A fues is ok. Relay never picks to cause it the run. Fuse for the relay is good as I have 12v @ the relay coil. Coil is good and will pick if Grd is applied to coil. So is my ECU now bad?
What is the condition to cause this to run? I'm told it will run if theCATs are cold. OK, so how does it know they are cold? Does it look at ambient temp, EGT sensors? If I can find out what causes this system to decide it needs to run then perhaps I can decipher how to fix the actual problem. Thanks, George

[skier]

From my understanding SAI only comes on during cold start and is only present in tip b5 s4's. It heats air and sends it to the cats to improve their efficiency @ cold start.

If I were you I'd just delete it have more from by valve covers...when you chip your car just have it coded out...

[ChrisGS4]

+1 for coding it out 034 and integrated engineering both sell block off plate kits.

[hodrosS42001]

I haven't been able to locate much info for this system. I have a pump which won't turn on shortly after having the turbos replaced. Pump is fine, I even replaced the bearings. Hot jump it runs great. 40A fues is ok. Relay never picks to cause it the run. Fuse for the relay is good as I have 12v @ the relay coil. Coil is good and will pick if Grd is applied to coil. So is my ECU now bad?
What is the condition to cause this to run? I'm told it will run if theCATs are cold. OK, so how does it know they are cold? Does it look at ambient temp, EGT sensors? If I can find out what causes this system to decide it needs to run then perhaps I can decipher how to fix the actual problem. Thanks, George

When I purchased my S4 I had the same problem. Secondary Air Injection system would not turn on and it threw a CEL causing me to not pass inspection. It wound up being air pump was frozen. I took it off the car, took it apart, cleaned it and put it back together and it has worked fine every since. Apparently if the pump freezes its a common problem exhaust gas can actually work its way back up into the SAI system and burn out the relays. I wouldn't assume the pump is fine unless you take it off the car apply current and actually see it spin and blow air. I would start there.. just to be sure.

[phila_dot]

Mainly coolant temp at start

[MonroeS4]

Exhaust gas CANNOT get back into the system and damage a relay I don't know who gave you that bit of garbarge. If you read the post you would note I alreasdy rebuild the pump with new bearings the problem is there is no "pick" signal to the pump relay and I'm trying to find out what is the component that detects the ECU to run the pump. Thanks anyway.

[MonroeS4]

Bing, almost correct. Actually is forces clean air into the exhaust so there is additional oxygen to ignite the unburned hydro carbons and thereby quickly heat up the CATs so they can now work to provide a cleaner exhaust output. I don't CHIP around problems, I prefer to correct them. My car has 200K+ and I'd like to keep it stock and running the way it was designed. There is absolutely no reason to defeat this system. I'm just looking for enough info so I can fix it. Thanks.

[MonroeS4]

Thanks, but I didn't ask how to bypass the SAI system, I'm interested in fixing the problem. Thanks

[MonroeS4]

Phila_dot, I thank you for the only useful reply I got. I'm having EGT error also, but they predate this SAI pump issue by about 8 monthsb but thought it might be related.
I always heard the pump run for about 20-30 seconds on cool/cold days. But I'm wondering now in the 90 whether it should still run. Took it to the shop that put in the turbos and all new SAI hose/manifold. He said pump is frozen, $780 for new one. Did some research, pulled the pump in 10 min, disassembled in 20. Found it to be binding a little. Oiled the bearings and it ran great. Left it out for a day, got new bearings for less then $2 and replaced them. Pump is a screamer now, but it never runs during startup. If I pick the relay it runs great.
So I'm trying to find out exectly what causes the ECU to send a "pick" signal to the relay. I've run some wire to a LED I put by the dash which will show when 12v gets to the pump and so far in 2 days of normal use....NEVER has it turned on.
I only have a basic VAG so I can't run the output tests to simulate the conditions. Guess I'll have to go back to the shop and ask him to test it if I can't get enough info here. Anyone in the Orange county of NY or Northern NJ have a real VAG that can run the tests? Thanks

[jimbo1234567]

the pump picks the signal up to run from the coolant temp sensor thats on the gallery at the rear of the engine that connects the waterways of the 2 heads, it runs for approx 2 mins on cold startup and its to dilute the emmisions and pass tests in strict countries. have you tried connecting a 12 supply tothe pump itself while in the car.

[hodrosS42001]

Exhaust gas CANNOT get back into the system and damage a relay I don't know who gave you that bit of garbarge. If you read the post you would note I alreasdy rebuild the pump with new bearings the problem is there is no "pick" signal to the pump relay and I'm trying to find out what is the component that detects the ECU to run the pump. Thanks anyway.

The mechanic at my local Audi Dealer described this to me as a common issue. If relay works but the pump does not instead of air being forced into the exhaust to warm up the 02 sensors, hot exhaust gas works its way upward into the system burning out the relay and potentially the pump. I read your whole post and even if you rebuild something it doesn't mean you did a correct job or the pump did not freeze again. And everyone has told you a "cold start" the ecu gets a signal from the coolant temp.

Edit. A little less hostility and a little more understanding will get you a long way. (Typical New Yorker)

[hodrosS42001]

the pump picks the signal up to run from the coolant temp sensor thats on the gallery at the rear of the engine that connects the waterways of the 2 heads, it runs for approx 2 mins on cold startup and its to dilute the emmisions and pass tests in strict countries. have you tried connecting a 12 supply tothe pump itself while in the car.

x2

[phila_dot]

Check measuring block 104 (first field), coolant temp at start must be between 5.25 and 60 * celcius to activate SAI.

Also IAT must be between 5.25 and 99 * celcius.

There are a few other conditions, but they are not likely to be causing your problem.

[MonroeS4]

HodrosS42001, All I asked was info on what picks the relay to run the pump. Not your opinion of my work abilities. So if YOU were so smart why didn't YOU suggest it originates from the water temp? Only Phila_dot mentioned it before I responded to those first 4 replys, later Jimbo also mentioned it. You didn't ever. You also suggested I rebuild the pump after I clearly stated it was already rebuilt. I also never stated WHO rebuilt it. Also stated the pump runs EVERY time 12v is applied to it. It draws less then 20 AMP on a 40 AMP circuit so there is no excessive load such as a bind. Now try if you can to explain how hot gases get past the combi valves firstly. Then after they do they would flow backwards up through the pump. If the pump isn't spinning there is no restriction so they exit at the rear of the engine. Please tells the rest of us how those gases get into the closed ECU box and damage a electric relay.
I admit I do not know the programming of the ECU or how it decides to run the pump. But 50+ years dealing with electro/computer technology I do know that everything else in the circuit is working fine.
As I said the mechanic told you a something which cannot happen. As for my attitude, those who actually tried to help with a reasonable solution were thanked for their efforts. Improbable answers were handled differently. So now that you knocked ALL New Yorkers with your myopic biased view may I suggest....perhaps though I live in NY now, I might have grown up in the same little backwater place you did. Do me a favor and don't help me in the future and we all will be happier. I'm still learning new stuff, just not anything so far from you. Thanks

[hodrosS42001]

HodrosS42001, All I asked was info on what picks the relay to run the pump. Not your opinion of my work abilities. So if YOU were so smart why didn't YOU suggest it originates from the water temp? Only Phila_dot mentioned it before I responded to those first 4 replys, later Jimbo also mentioned it. You didn't ever. You also suggested I rebuild the pump after I clearly stated it was already rebuilt. I also never stated WHO rebuilt it. Also stated the pump runs EVERY time 12v is applied to it. It draws less then 20 AMP on a 40 AMP circuit so there is no excessive load such as a bind. Now try if you can to explain how hot gases get past the combi valves firstly. Then after they do they would flow backwards up through the pump. If the pump isn't spinning there is no restriction so they exit at the rear of the engine. Please tells the rest of us how those gases get into the closed ECU box and damage a electric relay.
I admit I do not know the programming of the ECU or how it decides to run the pump. But 50+ years dealing with electro/computer technology I do know that everything else in the circuit is working fine.
As I said the mechanic told you a something which cannot happen. As for my attitude, those who actually tried to help with a reasonable solution were thanked for their efforts. Improbable answers were handled differently. So now that you knocked ALL New Yorkers with your myopic biased view may I suggest....perhaps though I live in NY now, I might have grown up in the same little backwater place you did. Do me a favor and don't help me in the future and we all will be happier. I'm still learning new stuff, just not anything so far from you. Thanks

During a cold start which is determined by IAT the ECU sends a signal through the relay to start the secondary air pump. Also the regulation valve opens to allow vacuum to reach and open the two silver valves that allow the path of air from the pump to enter the exhaust channels of the cylinder head. IF THE PUMP DOES NOT PROVIDE ANY AIR. The valves are still open, and exhaust gases from the cylinder head can enter both valves and eventually the pump. This over time can ruin the valves the pump. SO yes it is possible, and as my Audi Mechanic said its common.

Read/learn:

http://www.dj-sures.com/GraphicFiles...r%20system.pdf

And I didn't grow up in a "backwater place" and I didn't knock "New Yorkers" you did that yourself by not respecting to everyone who's posted trying to help you. No one said you have to follow what any of us say or believe it.

[MonroeS4]

Pila_dot, are you sure? That would mean if the coolant were between 60F and 140F it will still run. I was wrong thinking cooler temps were required. Since the turbos were replaced I have intermittent outside air temp reading 10F lower than actual and random O2 sensor faults. All O2 sensors were replaced with turbos. EGT open faults were present before and still occur but less frequently since the major repair. EGT doesn't cause a CEL or drivability problems but the SAI code causes decreased performance and lower MPG. Thank you for your insight.

[phila_dot]

Pila_dot, are you sure? That would mean if the coolant were between 60F and 140F it will still run. I was wrong thinking cooler temps were required. Since the turbos were replaced I have intermittent outside air temp reading 10F lower than actual and random O2 sensor faults. All O2 sensors were replaced with turbos. EGT open faults were present before and still occur but less frequently since the major repair. EGT doesn't cause a CEL or drivability problems but the SAI code causes decreased performance and lower MPG. Thank you for your insight.

Positive.

Check block 104.

[Sales@J-Fonz]

Code them out and delete the pump etc IMO

You will save money in the long run... One less system you have to service.

[MonroeS4]

As you now have restated what I said, I will repeat....no way the exhaust gases can affect the relay as you fisrt suggested. ("Apparently if the pump freezes its a common problem exhaust gas can actually work its way back up into the SAI system and burn out the relays.")
The irony is that your present answer is exactly the answer I would have appreciated as you first reply. It's factual and helps. I wish you had provided this instead of what you did.
Thanks for this info, it's what I'm trying to learn. Pump runs perfectly both on the bench and in the car. All SAI hoses and manifolds are new, Heads were cleaned with probes and such. Oil lines to the turbos all replaced. Mechanic ran and then had me also rerun several cycles of BG 109 to soften any carbon and hard deposits throughout the engine. Previous owners either ran it quite hot or poor oil choices causing clogged lines. I'm the 4th owner. Turbo oil lines were so plugged that in the cold weather the oil would pour out of the seals because it couldn't get through the line to return. We didn't know that till the turbos were pulled so they were replaced along with everything he could find that was clogged. Car ran great for 5 months now this weird stuff started and pointed to the pump. Pump now no longer a suspect since I have a LED on the dash which will illuminate if 12v is applied to the pump. Never has it come on in 3 days now. Thanks

You started with the remarks("Typical New Yorker"), I just responded in kind.

[MonroeS4]

Slaes@ J-Fonz-That's a solution, but not what I choose to do thanks.
I really care that it may be a little bit better for our kids and grandkids if we don't defeat the emission components, Cats or Air pumps included. My choice that's all.
I wish I knew more about the ECU programming and that's why I came here, to ask those who know more than me. I'm used to tracing circuits and program cycles but I cannot find any info on this SAI system yet.
Considering the pump has 200K+ miles on it and cost $2 for parts and 1 hr labor to fix, it's a cheap system to maintain.
I'm hoping it's not the ECU, because if it is I'll probably take these suggestions to code it out, under increased consideration. Thanks for the input.

[MonroeS4]

Phila_dot-I'll see if I can tomorrow before I go to work. Hope my trial VagCom proggie will do this function. Is this value also available via the Heating AC readouts? Thank you.