*DIY* - B5 1.8T Vacuum/Check Valve/SAI/PCV - Delete & Simplification

**walky_talky20** · 08-02-2011 07:38 PM

>> PDF VERSION WITH PHOTOS - CLICK HERE

There have been a lot of questions lately about doing Emissions deletes on the B5 1.8T. User "absolutegtr" did a very nice writeup for the B6 1.8T guys here:
http://www.audizine.com/forum/showth...simplification

There is nothing quite like it for the B5's. I hope this DIY will stand in that gap.

Goals:
Simplify the under-hood vacuum system
Identify specifically what does, and what does not cause DTC codes (and subsequent Check Engine Light illumination)
Get rid of "all those check valves", after first understanding what they are for.

Note 1: There are differences in the vacuum and PCV systems between almost every year of the B5. I will do my best to identify the differences. That said, most of the deletes discussed here will apply to the 2000+ cars. The 97-99.5 AEB emissions system is already pretty simple as it is.

Note 2: Since this is something I did a while back, it won't be a step-by-step type of the thing. You can rip this crap out in whatever order you deem necessary and effective. Onward.

For each system we will first take a look at the factory setup and determine what exactly we want to remove. We will be going through the systems in a piece-wise fashion for those that only want to delete certain parts. The following will be covered in order:

1. Secondary Air Injection system (SAI)
2. N249 (Electronic control of Diverter Valve)
3. Suction Jet Pump
4. Vacuum Reservoir (constant vacuum source)
5. Evaporative Emissions (EVAP)
6. PCV refresh

*If there are any errors in anything I've shared, extra information that should be added, or crap I just plain got wrong - please do not hesitate to correct me on it. This is meant to be a resource for B5'ers, so your input is appreciated.

**walky_talky20** · 08-02-2011 07:38 PM

SAI System

Application Notes:
Only 2000+ has SAI.

A little discussion:
The SAI systems entire goal in life is to push fresh air down the exhaust during a cold start. The extra oxygen in the exhaust stream, combined with the excess hydrocarbons from the cold start enrichment, create an “afterburn” effect which serves to heat up the catalytic converter much more quickly. All of this happens in the first 60-90 seconds after a cold start. While that is great, it doesn’t have anything to do with how good your car runs. All the rest of the time after the 90 seconds is over, it is just dead weight and extra crap to work around under the hood of your car. Add to that the high failure rate of several of the parts and the high cost to repair the system and we've got a real winner.

Here is the factory vacuum system.

What we are looking at:
Highlighted in BLUE is the Secondary Air Injection Pump. In RED is the SAI fresh air piping. In VIOLET is the Combi valve. In GREEN is the vacuum line to the combi valve. In ORANGE is the N112 SAI solenoid valve. In PINK is the path to constant vacuum source for the N112.

Things to consider:
Deleting this entire system will cause 1 code: P0441: SAI incorrect flow. This is unavoidable unless you get it "coded out" in your ECU software. Other than the DTC code and CEL, it will also cause 1 emission monitor (SAI) to not pass "readiness". If that is applicable to your state emissions inspection program (ie: they check OBD2 readiness), you may not be able to delete this system. Some states allow 1 or 2 readiness monitors to fail. So you may get by that way. Of note, you must leave the N112 solenoid plugged in electrically, or it will set an "open circuit" code. You can remove all the vacuum lines from it (GREEN, PINK), but you must leave it plugged in electrically, OR replace it with a suitable resistor. Direct fit resistors are available from www.postreleased.com.

What you have to do:
You will be removing the pump itself, the accordian hoses at the pump, the metal hard line that is mounted to the front of the turbo, the metal hardline that is mounted to the valve cover, the combi valve at the back of the head, and the vacuum line to the N112. Heck, I even deleted the bracket that holds the pump to the car, so have at it. If you aren't doing any other deletes, you would just cap that port on the N112. Further deletion of the constant vacuum source system (PINK) will be covered later.

Upon deletion of the combi valve, you will need to block off the port on the head where it was, else you will create a huge exhaust leak. You can buy one from various vendors (IE, 034, etc) or you can just make one. I used a square slab of scrap steel, the factory metal gasket that was there, and some high temp silicone to make sure it sealed up.

You will also have to plug the hole in your airbox after you remove the line. Go to your favorite parts store and ask for an "expanding plug" in the 1 inch size (as I recall). They will immediately pull out from behind the counter this magical device that seems like it was designed for the express purpose of plugging that hole. It is simply too magical to hang on the shelf, so they keep them locked away. It looks like this:

**walky_talky20** · 08-02-2011 07:39 PM

N249 Delete

Application Notes:
Only 2000+ has the N249 valve.

A little discussion:
On 2000+ 1.8T's,the diverter valve is not directly connected to the intake manifold like it was on the earlier 1.8T's. It is connected through a solenoid called the N249, which is able to connect it to the manifold (in it's passive state), or connect it to a constant vacuum source (in it's active state). Thus, the ECU is able to open the DV in situations where it would otherwise be closed. It is somewhat controversial to modify this system as solenoid control of the DV does have its advantages. It is able to help with pre-spooling the turbo (opening the DV at part throttle when boost request is low), and opening the DV sooner upon throttle lift. Many owners who have "deleted" the n249 have noted more "crisp" boost and more predictable DV response. In any case, the 97-99 cars did just fine without it, so we can delete it too.

**Here is a thread which discusses the pros and cons of deleting the N249: http://www.audizine.com/forum/showth...-Pros-and-cons

Here is the factory vacuum system:

What we are looking at:
RED is the vac line from DV to N249, GREEN is from manifold to N249, PINK is the path to constant vacuum source to N249.

What you have to do:
You will be connecting the DV directly to the manifold. Again, you will be leaving the solenoid itself in place and plugged in electrically while removing all the vacuum lines from it. If doing only this delete, you will simply "loop" the valve, as shown by the GREEN line below - leaving the PINK vac source in place. This delete causes no codes at all, so long as the n249 stays plugged in. Again, a suitable resistor could be put in its place.

**walky_talky20** · 08-02-2011 07:40 PM

Suction Jet Pump

Application Notes:
97-99 (AEB) automatic cars have the SJP, but vacuum routing may look slightly different.
All 2000+ have the SJP and should look like the diagrams shown.

A little discussion:
The suction jet pump (SJP) is used as a vacuum amplifier for the brake booster. It uses the venturi effect to do this. This device is equipped on 97-99 1.8T's with automatic transmission, and all 2000+. The theory is nice, but in reality it is kind of a joke. It uses flow from the PCV system to create the effect, and requires that flow to go through a very small passage. Obviously with the oil and contaminants in the PCV system, this passage becomes quite easily blocked, killing all the effectiveness of this valve for braking purposes. It also simultaneously cuts off the vacuum source the crankcase: not good. Vacuum to the crankcase is important to evacuate blow-by emissions, and a properly working PCV system is even more important on a turbocharged car due to the increased blow-by. Add to this that the SJP is made of plastic and likes to explode itself after a couple years of full boost (to the face), this device is major fail on several counts. Here is the factory vacuum system (yet again):

What we are looking at:
RED is the SJP, BRIGHT GREEN, is the line connecting it to the manifold, PINK is the "h" splitter hose, BLUE are some check valves that make this mess work, ORANGE is the 3-way check valve's connection to the manifold, YELLOW is the 3-way check valve's connection to constant vac source via the other BLUE check valve. DARK GREEN is the SJP's connection to the PCV system (remember that flow we talked about?).

What you have to do:
You will be ripping all this crap out. If you are only doing this delete, you can must use a "T" at the manifold (shown in red), else hang on for the delete of the constant vacuum system. When deleted, you will need to bridge the gap between the existing large vac line (BRIGHT GREEN), and the brake booster line (BLUE). I used a brass barb coupler and piece of rubber hose (BLACK). Make sure you clamp it well because this line will see full boost. For the PCV system, it will now be connected direct to the manifold, just like the older AEB manual trans cars. I used the existing "S" hose from the PCV valve (DARK GREEN), a brass barb coupler, and short piece of rubber hose (PURPLE) to do this. Again, clamp it well as it sees full boost.

Here are some photos of the actual install on the car. Colors from the diagram above are carried over to help explain things a bit:

**walky_talky20** · 08-02-2011 07:41 PM

Vacuum Reservoir System

Application Notes:
97-99 (AEB) cars use vacuum to operate the cruise control, so deleting this completely may not be possible. AEB owners, please feel free to add insight here.

A little discussion:
If you decide to delete all of the above (SAI, N249, and SJP systems), you will now have no more use for the constant vacuum system, so it can be deleted as well. Here is the factory diagram (with all previous deletes removed):

What we are looking at:
PINK is the “F” hose, BLUE is the braided hose that runs to a plastic hard line. Said hard line continues and connects to the actual vacuum reservoir in YELLOW.

What you need to do:
You can take all of that out. I chose to just remove the 2 hoses in the engine bay and leave the stuff in the fender alone. The plastic hard line from the fender comes out under the coolant reservoir and can’t really be seen. Here are some photos showing the stuff removed, and the remaining line I left:

**walky_talky20** · 08-02-2011 07:41 PM

EVAP system

A little discussion:
I’ve chosen not to delete this system for a few reasons. This system is responsible for burning off the fuel vapor emissions from the fuel tank. It does this in a regulated fashion so as not to upset the air fuel ratio. The system (in the engine bay anyway) is pretty minimal – consisting of just 3 check valves, the purge valve, and some tubing.

Things to consider:
None of this is extremely ugly, cumbersome, or failure prone, in my opinion. Deleting it will cause 2 codes (I believe, again I didn’t do it): 1 code for EVAP incorrect flow, and another for lack of vacuum source to the Leak Detection Pump. Here is the factory vacuum diagram:

What we are looking at:
Starting from the left, DARK GREEN is the purge valve, VIOLET is the “F” hose, BLUE is a check valve, ORANGE is the line to the Turbo Inlet Pipe. RED is the line across the firewall, BLUE is another check valve, GREEN is the line to the manifold, BLUE is another check valve, and PINK is the line to the Leak Detection Pump.

What you have to do:
You can remove all of that if you wish. You will leave the purge valve in place and plugged in, just tuck into the fender. Obviously the opening in the turbo inlet pipe would need to be plugged as well as the port on the manifold. The stuff should like this when removed:

**walky_talky20** · 08-02-2011 07:42 PM

PCV Refresh

Application Notes:
The parts I show here are applicable for 2001+ only. The 2000 and earlier use a different plastic pipe. A kit is available for those cars here:
http://www.ecstuning.com/ES5942/

As the vast majority of the interest here is the “PCV” system, I thought I should address what I did to freshen mine up “while I was in there”. When I pulled all this crap out, it was in quite bad shape:

All busted up and leaking and such. So I got this stuff new:
http://www.ecstuning.com/ES523283/
http://www.ecstuning.com/ES258895/
And I cleaned out this guy (PCV Bleeder Valve):
http://www.ecstuning.com/ES5957/

And installed as such:

I reused the stock “S” hose, the one that connects to the Bleeder Valve there (shown in first photo). Recently there has been some development in this area by 034 motorsports. You can now buy a silicone “S” hose, and a billet aluminum PCV bleeder valve. Just the other day I noticed my re-used “S” hose is starting to tear and leak slightly (dag-nabbit!!), so I hope to install those 034 items soon. Check out their stuff here:

http://www.audizine.com/forum/showth...d=12&styleid=8

Many people have decided to remove the PCV valve and the manifold connection to the PCV system and just vent it to atmosphere. I feel that is certainly applicable to high horsepower/Big Turbo cars. With a stock turbo, it is my opinion that simplifying and keeping the stock system working well is the best route. Discussion of “catch cans” and other system re-routes and modifications is outside the scope of this DIY, but feel free to discuss amongst yourselves.

**Papa_Dios** · 08-02-2011 08:00 PM

Great job as always here's my simplified bay (albiet dirty) I still decided to run a hose from the crankcase breather to the TIP (minus pancake valve).

IMG_20110731_202449.jpg by Papa_Dios, on Flickr

**biketsai** · 08-02-2011 08:10 PM

Awesome, Im glad this is written out clearly for us 00+ guys! Great contribution!

**Coopa** · 08-02-2011 08:19 PM

This is a terrific write up WalkyTalky, kudos. I'd rather not have codes from it tho..can you just use vag-com to keep them from tripping a cel?

**Coopa** · 08-02-2011 08:20 PM

Should probably just sticky this lol

**walky_talky20** · 08-02-2011 08:26 PM

Originally Posted by Coopa

This is a terrific write up WalkyTalky, kudos. I'd rather not have codes from it tho..can you just use vag-com to keep them from tripping a cel?

The only codes you'll get are from the SAI or the EVAP, which are described above. They can be "coded out" of the software, but you need *a lot* more the vag-com to do it. The EVAP lines wouldn't be difficult to "hide", if you wanted to make them go away. But the SAI is bummer because you need all the equipment to make it work. I suppose you could get creative and hide that stuff too.

**Seerlah** · 08-02-2011 08:38 PM

I stumbled upon a link in a different thread with resistors built into connectors, that could come in handy.

http://www.postreleased.com/

Ordered 4 (for n75, n112, n249, and possobility of VVT in the future) and will more than likely order the oval one for the N80 soon. You won't even need to place that bracket with soleneoids back under the IM and can remove the n80 completely. The resisitors should work on all the solenoids being tampered with, minus the SAI. That will need to be coded out of your ECU. I have not confirmed this myself, but the B6 people have all had sucess with these (where I found the link).

Oh yeah, great write up!

**Coopa** · 08-02-2011 08:39 PM

That's what I was thinking. Just wanted to double check. It's not like I don't have a cel on right now anyways = P

**biketsai** · 08-02-2011 08:45 PM

Originally Posted by Seerlah

I stumbled upon a link in a different thread with resistors built into connectors, that could come in handy.

http://www.postreleased.com/

Ordered 4 (for n75, n112, n249, and possobility of VVT in the future) and will more than likely order the oval one for the N80 soon. You won't even need to place that bracket with soleneoids back under the IM and can remove the n80 completely. The resisitors should work on all the solenoids being tampered with, minus the SAI. That will need to be coded out of your ECU. I have not confirmed this myself, but the B6 people have all had sucess with these (where I found the link).

Oh yeah, great write up!

Pretty cool stuff, Lmk how they work out for you!

**walky_talky20** · 08-02-2011 09:12 PM

^ I was a little skeptical of those resistors just because they didn't publish the ratings on them. You have to remember you are applying full battery voltage, up to 14 volts, across a 36 Ohm resistor. Just think about the heat that is going to make. Almost 6 watts. So those little buggers are going to get hot. My thought was that the solenoids aren't hurting *anybody*, and I can't even see them without a mirror. So I'll just leave them alone.

EDIT: No longer skeptical. Toby from PostReleased has shared the resistor specs with me. Please see my update in Post #26.

**ECS Tuning-Audi** · 08-16-2011 08:37 AM

Awesome write up Keith! I sent you a PM I had a question about the install!

Jason

**auh** · 09-23-2011 07:31 AM

I was just thinking to myself the other day, did walky ever make that write up??? Now I see I found my answer! Yay!

However after reading this, it doesn't sound like its useful for me(as an AEB owner) to really delete anything at all. Maybe just do the PCV clean up, but I'm still trying to make time to do my OCC.

**xdewaynex** · 09-23-2011 08:08 AM

Originally Posted by auh

I was just thinking to myself the other day, did walky ever make that write up??? Now I see I found my answer! Yay!

However after reading this, it doesn't sound like its useful for me(as an AEB owner) to really delete anything at all. Maybe just do the PCV clean up, but I'm still trying to make time to do my OCC.

AEB here and I deleted the pcv and all vacuum and check valves, except for the brake booster, and lines needed for boost gauge and turbo. I will say, that since I deleted all the vac lines, I never hooked my vac reservoir back up, and my cruise control doesnt work. Ill be hooking it back up soon and seeing if that fixes it. I also done an occ setup, with the use of 034's block breather adapter.

**turbo kraut** · 12-07-2011 06:30 PM

back from the dead bump

yay, we actually have a write-up for the b5..... i'm going to be doing this in the very near future.... like maybe this weekend... lol

don't have a catch can yet, so will probably dump under the car for now....

**Seerlah** · 01-18-2012 10:10 PM

Originally Posted by walky_talky20

^ I was a little skeptical of those resistors just because they didn't publish the ratings on them. You have to remember you are applying full battery voltage, up to 14 volts, across a 36 Ohm resistor. Just think about the heat that is going to make. Almost 6 watts. So those little buggers are going to get hot. My thought was that the solenoids aren't hurting *anybody*, and I can't even see them without a mirror. So I'll just leave them alone.

Integrated Engineering now offers these resistors on their website, from the same company on the link I previously posted. If IE is willing to sell them on their website, I am sure they are safe. Anyways, I should be doing the delete shortly, when the good weather comes back out.

**dcampana** · 01-19-2012 11:54 AM

i too will be doing the "clean up" . tired of all the bogus crappy lines.

**Seerlah** · 01-23-2012 04:08 PM

I have a question. Where do you guys tuck the harness for the SAI, MAF, and N80?

**SS92** · 01-23-2012 04:20 PM

Question for those deleting/deleted Evap - My Check Valves are shot and causing a vac leak. I have a year before emissions so I'm thinking of a year long hiatus of the evap system. Any negatives besides the CEL? Can it cause bad A/F Ratios?

Seerlah, you have enough slack to tuck yours or are you running mafless? Mine barely reaches the maf as it is. I just let SAI/N80 hang down

**Seerlah** · 01-23-2012 04:47 PM

I didn't do it yet. I want to do it the same time I install my turbo kit, and will be running a MAFless file with SAI delete. I'm thinking of deleting a whole bunch of stuff in the software though, including my n80. The 249 and n112 are def getting deleted. If my tuner can't do that, I have resistors for the solenoids I will use.

But I simply don't know where people tuck it. Behind the block, maybe? I don't want the wires getting all hot and frayed, though.

**walky_talky20** · 01-23-2012 05:21 PM

Originally Posted by Seerlah

Integrated Engineering now offers these resistors on their website, from the same company on the link I previously posted. If IE is willing to sell them on their website, I am sure they are safe. Anyways, I should be doing the delete shortly, when the good weather comes back out.

I would like to address my previous comments above concerning the resistors.

I was contacted directly by Toby from PostReleased. He assured me that the resistors he sells have been tested by many and work well and safely. The resistors used for the various solenoids are 330 Ohm and rated for 1 watt. The measured resistance of the actual solenoids is closer to 30 Ohms or so, but in Toby's experience (and his customers), the 330 ohm value is sufficient to satisfy the ECU's circuit tests. The higher resistance also makes for lower current and heat in the resistor, which is good.

The only application I cannot recommend for a resistor is the SAI pump itself. The pump circuit is relay-driven and as such, it is not metered by the ECU whatsoever. Putting a resistor in place of the pump will serve no purpose other than to waste electricity. The resistor would perform a function of keeping the harness connector clean and insulated, but a little bit of electrical tape would do that as well.

So, I am now in favor of replacing your deleted solenoids (N112, N249, N80, etc) with these plug-n-play resistors offered by PostReleased, if you so desire. Please check out the website here:
http://www.postreleased.com/

**Jimmy G.** · 01-25-2012 06:17 AM

Awesome writeup!. Walky , where did you get those red silicone hoses? Anything specific as far as temperature rating or anything i should look for? ALso, how would I get the system coded out of my eCU? Sorry I'm new with the 1.8t motor.

**walky_talky20** · 01-25-2012 01:25 PM

^To answer your questions:

1. Red hose was from ebay.
2. Yes, you should get decent hose. The stuff I got was cheap ebay brand, so I just used it for the boost gauge.
3. You have to talk to whomever tuned your car (APR, REVO, Unitronic, etc). If you are stock, PM user "k0mpresd" and he may be able to help you out.

**Jimmy G.** · 02-01-2012 10:32 AM

Thanks Walky.!

**Jimmy G.** · 02-01-2012 10:37 AM

Thanks Walky.!

**Seerlah** · 03-03-2012 01:27 PM

Hey Keith, I was wondering something. If you keep the line from the leak detection pump connected to the IM with a check valve in place, would you not get a CEL for it? That is my plans (going to do this maybe this coming week), along with removing the lines from the n80, keeping it plugged in, and tucking it into the fender.

**walky_talky20** · 03-06-2012 10:25 AM

Mitch, I think the answer is yes (yes, you would not get a CEL for it). You would minimally need to keep a manifold vacuum source (with check valve) connected to the LDP line to avoid the code from the LDP. The small section of hose that is needed to satisfy that is highlighted below:

I think you may be able to avoid EVAP "flow" codes by making sure the N80 remains plugged in and connected to the fuel tank line. The valve just vents into the fender. I don't think the ECU is looking to see that the fuel vapors actually enter the manifold. I'm not positive, but I believe it is just looking to see the tank pressure drop at a particular rate upon opening the N80. Somebody else might have a better answer for you there, but that is my best guess. It's bugging me a little bit that I can't be sure about this, so I'll probably look it up later.

**Seerlah** · 03-06-2012 05:11 PM

Thanks Keith. I'll also update on how the leak detection reacts, once I start my car back up.

I also have another question. Where do people tuck their wiring harness, after the delete. I have no use for any of the harness beyond where it splits for the ignition coils, and don't exactly know what to do with it.

**Poopie** · 03-06-2012 05:17 PM

just used this guide for avant. Thanks a whole bunch for taking the time to do this!

I ended up just removing everything with a vacuum line. Then ripped out the pvc system and ran -10 an lines from the crank and the valve cover to a catch can. 1 vacuum line for the brake booster and 1 vacuum line for the DV. Everything else got plugged and capped. Resistors on the n249, ect. Did i miss anything?

**andyrew** · 03-12-2012 02:47 PM

Poopie, you have pics of what you did with your PCV system?

**Poopie** · 03-12-2012 10:28 PM

yup should be done in a few days.

**redline380** · 03-13-2012 12:34 PM

Originally Posted by andyrew

Poopie, you have pics of what you did with your PCV system?

second. detailed photos would be awesome.

**Poopie** · 03-13-2012 03:34 PM

Just look for my thread in the main board. pics will be on there in a few minutes

http://www.audizine.com/forum/showth...num-parts-pics

**Seerlah** · 03-26-2012 05:02 PM

Wanted to update and say I did not get an LDP code when I had it hooked it up to the IM with a check valve. Not one CEL

.

**holywar0902** · 04-24-2012 03:41 PM

As far as the N80 and the evap system goes, has anyone gotten a p0441 code when they removed the hose from the n80? I put a check valve on the end of mine and still got the code. I am thinking about adding a hose to run to a vacuum source to fix it.

Also, over by the abs and washer bottle, there are 2 hard lines( not part of the abs) where do they run down to? I see they go into the fender but dont know what they connect to. Thanks