SAI - Removing it without actually removing it?

[Capt. Obvious]

Paging Old Guy, Diagnosticator and probably Greg as well.

So, this is my engine bay:

Not a lot left.

But, I'm getting tired of the check engine light being on from removing the secondary air injection, so I'm contemplating putting it back on. BUT, I want to do so in a manner that doesn't involve putting everything back on for it.

So, before I get to work, I want to run an idea past everyone to 1) see if my understanding of the SAI system is correct and 2) find out if my idea could even possibly work.

My understanding of the SAI system is that when the car is started cold, the SAI pump kicks on and pushes air into the EGR valve, which feeds extra unmetered air into the engine to make the car run leaner (and thus hotter) for a few moments to warm up the catalytic converter faster.

Correct?

SO, with that said, will I be able to fool the car into thinking the EGR and SAI are still present if I were to instead put the SAI pump back on the car and instead of having it feed the EGR valve (which I would like to leave off), have it force air into the TIP (post-MAF, so it's unmetered), which would cause the car to run slightly lean?

Thoughts? Ideas? Suggestions?

[dougyfresh]

My understanding of the SAI system is that when the car is started cold, the SAI pump kicks on and pushes air into the EGR valve, which feeds extra unmetered air into the engine to make the car run leaner (and thus hotter) for a few moments to warm up the catalytic converter faster.

That is correct. It puts additional air into the exhaust ports in the head to lean out the exhaust mixture for cold starts.

I don't believe its an EGR valve per-say.

SO, with that said, will I be able to fool the car into thinking the EGR and SAI are still present if I were to instead put the SAI pump back on the car and instead of having it feed the EGR valve (which I would like to leave off), have it force air into the TIP (post-MAF, so it's unmetered), which would cause the car to run slightly lean?

Thoughts? Ideas? Suggestions?

Your code is for insufficient flow. In your case it is because there is no flow in the head. Where the ECU is sensing this? I do not know. I don't believe there is an electrical connection on the valve in the back of the head. That only has a vacuum line coming from the N249 valve (I think thats the valve). Trying to recall my car (SAI is completely removed) the only electrical connection I have is the SAI pump itself.

I know you don't want to do this but I would try to hook up the valve on the head and run the lines under the turbo and relocate the pump back to where it was. You'll basically be putting the system back in but hiding all the lines so the only thing you'll see is the valve on the back of the cylinder head.

The key here is that the additional air is post combustion. That is how the factory can get away with leaning out the mixture. You don't want to lean out any mixture for combustion itself.







OR, you can talk to kompressd and he can set readiness to 'okay' for you within your ECu. That will allow you to keep the SAI system out of your car.

[Capt. Obvious]

OR, you can talk to kompressd and he can set readiness to 'okay' for you within your ECu. That will allow you to keep the SAI system out of your car.

Is this a VAG-COM tweak of some sort, or is it in conjunction with ECU software?

[F16HTON]

SAI is a ULEV requirement, has no real affect on how the car runs. Contact David @ Eurocode, he can take care of the MIL for you.

[A4natomical]

Contact David @ Eurocode, he can take care of the MIL for you.

^^I need to do this soon

[dougyfresh]

Is this a VAG-COM tweak of some sort, or is it in conjunction with ECU software?

He'll physically go into your ECU and change a few things. You can not do this with VAG-COM. The only way to set readiness to 'good' is to physically tweak a few files on the ECu.

Its more than just setting readiness to 'good' too. You need to change a few maps to set the cold starts up properly. Otherwise cold starts will be rough.

What software are you running? If REVO, follow Greg's advice.

[Capt. Obvious]

Its more than just setting readiness to 'good' too. You need to change a few maps to set the cold starts up properly. Otherwise cold starts will be rough.

Cold starts have been perfect. It's been in the teens and 20's here and it fires right up every morning.

[dougyfresh]

Cold starts have been perfect. It's been in the teens and 20's here and it fires right up every morning.

But it probably idles rough, right? If you try to tap the gas it'll probably stall?

[lookaught]

Does anyone know how much Eurocode charges to do this? Perhaps in conjunction with buying a BT software flash?

[lookaught]

Your code is for insufficient flow. In your case it is because there is no flow in the head. Where the ECU is sensing this? I do not know.

Perhaps it infers it from the lower than expected EGT's when the pump isn't running.

[vinny.dtw]

My sai is removed, and my car doesnt get a code....not anymore at least. It does get triggered once in a while if i don't let my car sit and warm up enough before I drive it. I have revo's file.

[dougyfresh]

My sai is removed, and my car doesnt get a code....not anymore at least. It does get triggered once in a while if i don't let my car sit and warm up enough before I drive it. I have revo's file.

This is an intermediate check that throws off the CEL. It won't happen on every start-up.


Dunno the specifics of what triggers it, Jon. Only thing I really know is my car was reprogrammed and I was told a little bit about everything that was reprogrammed. And when the changes were made my cold starts and idle and just off idle functionality turned back to stock-like from having a rough time.

[vinny.dtw]

Yea, but my idle is perfectly fine. In the cold of 1 degree to 32 degrees. So who knows, there's no point with me having the SAI since i don't even have a fricken Cat anymore

[actlsub9]

But it probably idles rough, right? If you try to tap the gas it'll probably stall?

I never had a single problem with cold starts or idles when my SAI was unplugged.

[Capt. Obvious]

I never had a single problem with cold starts or idles when my SAI was unplugged.

Same here. No rough idle or stalling if I blip the throttle. Runs perfect. It's probably kinda like running an open diverter valve, some cars do fine with it, some run like crap.

[[email protected]]

When you drop off the car to have the BT installed I'll have the SAI code removed from the software

[orangelmo]

I'm assuming you guys don't have to deal with emissions testing. If you do, how do you get it to pass with everything missing?

[[email protected]]

I don't have to have my car tested for emissions until 2014 and even if it did get tested they do it via the OBD port to see if any codes are present.

[dougyfresh]

I'm assuming you guys don't have to deal with emissions testing. If you do, how do you get it to pass with everything missing?

They plug my car's OBDII port into their computer and scan the car. If all readiness codes pass my car passes emissions. My SAI is always set to 'pass' for readiness

[Spinnetti]

He'll physically go into your ECU and change a few things. You can not do this with VAG-COM. The only way to set readiness to 'good' is to physically tweak a few files on the ECu.

Its more than just setting readiness to 'good' too. You need to change a few maps to set the cold starts up properly. Otherwise cold starts will be rough.

What software are you running? If REVO, follow Greg's advice.

Thats good info, and my car does act like a carby car on cold starts in cold weather (BT, Revo, no cat, stalls on gas after real cold start). I hate the constant warning light too, but I'm not happy with Gregs source, or that they would even do it for me (where I got ALL of my stuff from). Is there any other vendor that can do it?

[old guy]

The SAI system has no effect on the idle during a cold start. The SAI pumps air into the head post ignition and mixing with the exhaust outflow. The ECU is looking for a lambda integrator signal from the primary O2 sensor to determine if the extra O2 is present. Re-routing the SAI into the TIP will not work. Your only options are to have someone write the code out or leave it hooked up.

Sorry!

[Capt. Obvious]

Darn, maybe I'll just put the EGR and SAI back on for the time being then.

[Dopefish]

Capt, your engine bay looks fantastic! Any more images of it? I like the painted engine covers and clear turbo area. Is that Amulet red?

I presently have APR Stage 1+, when I went to ETA to have the update for my testpipe added, I asked if they could write out the SAI error as well and I was told no, David wasn't around to confirm though. Does anyone know more about that possibility with the APR software? I plan to go big turbo eventually and that will included the more popular REVO software but that is quite awhile away and the CEL is annoying for such a silly thing.

[B5A4Kevin]

i have the same improper/insufficient flow fault for my SAI, but my pump is still intact. ive had it ever since i installed my testpipe and cone filter, but i think i burned up my pump because i just used a vacuum cap for the inlet hose (poked about a million holes in the cap).

there is no egr on the 1.8t as it was eliminated by using vvt to achieve the same end. the valve on the back of the head is the Combi-valve (combination). and flow is determined by signal voltage from the primary 02 while the pump is activated.

ive just been clearing the fault every 2 weeks or so, once it sets. pisses me off because it erases my fuel trims when i clear it, but o well. ive also heard you can eliminate the pump all together by wiring in a 650 ohm resistor in its place, but you would still get the flow fault, just not an additional open circuit fault.

[A4natomical]

btw way darrick, you keep your car insanely clean, being that you are in washington.

you must get your panties in a knot when it rains. haha

[Capt. Obvious]

btw way darrick, you keep your car insanely clean, being that you are in washington.

you must get your panties in a knot when it rains. haha

LOL, it's filthy right now, but I do try to keep it really clean.

[1point8teeNW]

You need an R8 oil cap and then paint all the other caps black along with the coolant res..

But when have you ever taken advice, lol.

Clean engine bay.

[Smiley]

I must be retarded, but wheres your intake?

[Raus]

I must be retarded, but wheres your intake?

In that pic it I see a clamp and hose right under the headlight, looks like a custom setup pulling in air from the lower bumper area.

[Capt. Obvious]

[NyteEscape]

i know nothing of what you are trying to do, so there is no way i can help.

i just wanted to let you know that your engine bay is very pretty.

[czero]

He'll physically go into your ECU and change a few things.

Wow! Must be a small guy
OP:
The engine bay looks really clean, what intake manifold is that?

[Capt. Obvious]

The engine bay looks really clean, what intake manifold is that?

Stock. I just polished the top of it.

[Dopefish]

Thanks for the images, I love it! Gives me a few ideas to try out since I still think mine is a bit messy.

[FORCE_FED_DUB]

uni BT files can have everything written out of them as a free option. SAI, EVAP, N249, N112, CAT, MAF, etc.... but you have to be a uni BT customer to get this. and they are written out in a way that your OBD readiness will always display "PASS" when the emissions computer takes a look.

[czero]

Stock. I just polished the top of it.

Oh ok, never seen a longitudinal 1.8t motor so I didn't know if it was stock or not.

[orzech]

any updates on this? I want to remove all my vac.lines and such but i want to keep the SAI. I want it tucked away but im trying to completely understand how it all works first.

does the n112 valve receive vac/pressure from the intake manifold? or does it just dump into the vac. reservoir? I take it the vac reservoir is sealed up? Do i just cap the other end of the n112 valve? I plan on removing everything else but cant really figure out what to do with the vac line that comes out of the n112 and heads to the rats nest of other shit.

I am just confused which way the air flows after the it leaves the valve by the firewall and goes to the n112.

[old guy]

The N112 is essentially the same as the N249 valve with one of the ports blocked off. It functions as an on/off switch for the combi valve. You need a vacuum source going to the N112. That would be the straight line going to the "T" in the pic below. It's the valve on the right. The curved line leaving the N112 goes to the combi valve. The ECU activates the N112 which in turn pulls vacuum to open the combi valve allowing the SAI to pump extra O2 into the back side of the exhaust port.

[orzech]

The N112 is essentially the same as the N249 valve with one of the ports blocked off. It functions as an on/off switch for the combi valve. You need a vacuum source going to the N112. That would be the straight line going to the "T" in the pic below. It's the valve on the right. The curved line leaving the N112 goes to the combi valve. The ECU activates the N112 which in turn pulls vacuum to open the combi valve allowing the SAI to pump extra O2 into the back side of the exhaust port.

exactly what i needed to hear. going to go tackle all of this today. thanks a lot :)

[Matt Devo]

Cap'n, YGPM