# P0171 system too lean bank 1 troubleshooting



## K2Keith (Sep 11, 2006)

Hi all, have a 2007 gti giving me this code. Clear it and it comes back in 24 hours, so all but 1 emissions checks go to readiness, but the the CEL comes on and obviously in an emissions state I will have to resolve this before next march to pass inspection.

Just had the HPFP, Camshaft and follower replaced under extended warranty program. This code would periodically come up prior to the end of the HPFP breaking off (putting the car in limp mode) and actually after the warranty service I thought this would no longer occur. I thought it was a sign of the failing HPFP / cam follower but I guess not.

Is there a checklist to follow or measurement to monitor? Don't have VCDS but I'm using an ELM327 wifi obd-II and dash command iOS app. It does have some measuring blocks, mostly standard stuff like fuel trim, MAF sensor reading, etc.

Could this be a vacuum line or o2 sensor? Cars running so I don't know what else. I also replaced the Rev C. DV with a Rev D. one because I had an underboost code a month ago. Haven't had that particular code since. About 89,000 miles on the car. Turbo does make a whistle like noise if flooring it past 3000 Rpms so I'm wondering if that is a vacuum leak?


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## kbad (May 26, 2007)

hey man .. this makes me wonder if you have had the rms (rear main seal) checked/replaced .. how about the pvc and timing chain tensioner/cover seals? .. good luck!


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## K2Keith (Sep 11, 2006)

kbad said:


> hey man .. this makes me wonder if you have had the rms (rear main seal) checked/replaced .. how about the pvc and timing chain tensioner/cover seals? .. good luck!


I thought he rms was more of a problem in the TSI engines. Specifically a lot of Tiguan's had the problem due to a shotty manufacturing job of it.

I'm thinking to check the pcv because it seems it's a very common problem. I'm not sure the mechanics behind why it could cause fuel too lean bank 1, but I'll try to read up on it more, how it works. I believe people were talking about taking a running car and pulling the dipstick or oil cap and seeing if the idle changes, then the pcv is doing its job. I'm not getting the constant whistle like in a few of the YouTube sample videos of failed pcv's, but I sure get a whistle that seems to line up with boost in heavy acceleration.


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## GTI's (Nov 27, 2011)

Have you taken a good look at your brake booster hoses..both pieces


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## ROH ECHT (Dec 9, 2010)

Check your fuel trims...a vacuum leak will be evident there. If not...and you know the pcv(front and back) is in fine shape...I would replace the 1st O2 sensor. I wouldn't assume plugs, coils, or anything that would result in misfires because you would not get the lean code for any of that. Focus on causes of too much air and not enough fuel. Fuel pressures and filter too. May even be a fuel sensor sending the wrong info to the ecu and making an improper fueling request...but not as likely as the other possibilities.

https://www.youtube.com/watch?v=yM3iarhSP68


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## K2Keith (Sep 11, 2006)

Thanks everyone for the suggestions! ROH ECHT, That video really helped me understand the fuel trim readings. I have a 3 day weekend so hopefully I will find some time to check some of this out by Monday and go from there.


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## Fogcat (Apr 29, 2015)

When changing my fuel pump, I cracked one of the prongs on the check valve shown in the post above. I didn't even notice it at first but soon had what you've described. Just something easy to check and costs nothing to check but costs a lot if it is bad and money paid out for other things . Hope it works out and RON is a pro.


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## K2Keith (Sep 11, 2006)

I had this intermittent problem even before changing the HPFP. Anyway I can replicate the video exactly. I can pull the dip stick and watch short term fuel trim shoot way up to around 26%. Put the stick back in and it works it's way down to around 2-3%. I did drive some long highway driving this weekend. Reset trip and at 19 miles in had this CEL. Cleared it and it came back with 171.1 on the trip. Cleared it again and it came back around 323. I was out of town the weekend and had a lot of catching up to do today, but I think I will look for some leaks and check the PCV valve and also O2 sensor.


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## K2Keith (Sep 11, 2006)

Long time update overdue. Seems it's the brake booster hoses. Thanks for all the pointers and help. Def can change the amount and tone of the "hissing" from this assembly by manipulating my hand over it while the engine is running, and noticing a direct correlation to the short term fuel trim. I think I will get the whole kit, including the check valve for about $60 from DAP, rather than just the hoses which is $20 cheaper.


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## Luftpost (Jan 1, 2017)

*Help with part please....*

Hello all,

New to the forum and am tackling my first item with the 2008 Eos.

I am getting the P0171 code, as described in the posts above. I can see a crack in the vacuum line. So I bought the brake booster from an online supplier. It arrived today, but looks different from what I have in my car. It is my understanding that I have a FSI BPY engine (oil filter is on bottom, dipstick is on front passenger side of engine, FSI on engine cover). What I got today was this:










But what I really need is this and this......



















When I go to any online supplier, it always shows the valve with three fittings on it. What I need is the valve with 4 fittings on it. Am I looking up the wrong part? I suppose I could just repair the line with a new hose, but would prefer to replace the whole assembly.

Thanks for any help!

L


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## GTI's (Nov 27, 2011)

They sent you the vapor canister

https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/vapor-canister-check-valve-kit/06f133781l/

Your looking for this

https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/brake-booster-hose/1k0612041gm/

https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/brake-booster-hose/1k0612041kc/


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## Luftpost (Jan 1, 2017)

GTI's said:


> They sent you the vapor canister
> 
> https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/vapor-canister-check-valve-kit/06f133781l/
> 
> ...


Thank you for the quick response! I see the mistake now. New and correct parts are on order.

L


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## Luftpost (Jan 1, 2017)

The new vacuum lines did the trick for me. No more check engine light. Thanks for the good info. 

L


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## Jicafold (Mar 21, 2016)

So I have the same problem. A new P0171 code. It hunts and surges at idle and fuel economy seems down. I replaced both of the vacuum lines above and there is no change (I replaced the brake booster one last year and the other one today). I had a spare MAF sensor and that did not make a difference either. What do you suppose I should consider next?


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## Thy_Harrowing (Dec 7, 2014)

Jicafold said:


> So I have the same problem. A new P0171 code. It hunts and surges at idle and fuel economy seems down. I replaced both of the vacuum lines above and there is no change (I replaced the brake booster one last year and the other one today). I had a spare MAF sensor and that did not make a difference either. What do you suppose I should consider next?


Start by replacing PCV. If that doesn't do it PM me or post back.


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## Jicafold (Mar 21, 2016)

Hello. Thank you for your help. I already replaced the PCV with a block off plate a few months ago.


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## Thy_Harrowing (Dec 7, 2014)

Jicafold said:


> Hello. Thank you for your help. I already replaced the PCV with a block off plate a few months ago.


Have you checked the rest of the vacuum hoses? Have you checked for possible exhaust leak, possibly even at manifold? I've known several FSI/TSI owners (including myself) who had exhaust manifold studs loosen and fall out over the years somehow. I had a exhaust leak at manifold on passenger side corner due to a missing stud and a second one that was loose.

Otherwise you'll want to use a data logger to check the exact fuel trim and to check fuel pressure on low an and high end. These system lean codes more often indicate vacuum line leaks but if you rule that out then these are the other things you need to look into. If you suspect a particular vaccum hose then, while data logging, spray some carb cleaner (just a mist) or similar at the spot and if there is a leak you'll notice on the logger that your fuel trim goes richer briefly.


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## Jicafold (Mar 21, 2016)

I need to check the large hose running off the block off plate. Other than that....what other vacuum lines are there that we haven't yet discussed?

Why would an exhaust leak cause a P0171 code and a fluctuating idle? Because it is a turbo motor rather than naturally aspirated?


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## Thy_Harrowing (Dec 7, 2014)

Jicafold said:


> I need to check the large hose running off the block off plate. Other than that....what other vacuum lines are there that we haven't yet discussed?
> 
> Why would an exhaust leak cause a P0171 code and a fluctuating idle? Because it is a turbo motor rather than naturally aspirated?


Um, because an exhaust leak will allow umetered fresh air to enter the system on the negative pressure side which will cause an oxygen sensor to produce a lean reading. But I forgot you said it was surging: that is not typical of exhaust leak. I didn’t say exhaust leak was likely I’m just throwing out possibilities that can lead to this code based on what little info I have of your car. 

Do the carb cleaner test or a smoke test to rule out the vacuum lines, your eyeballs are not gonna cut it when a pinhole sized leak could be all it takes. 

Also check your N80 purge solenoid. If it gets stick open it can cause lean code among others.


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## Jicafold (Mar 21, 2016)

I appreciate your help. Headed back out to the garage....


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## Thy_Harrowing (Dec 7, 2014)

Jicafold said:


> I appreciate your help. Headed back out to the garage....


A bad N80 purge will often produce a loud rythmic clicking but so does a lot of stuff on the FSI so put your fingers on it and see if it is in sync with any clicking. Even if not it is such a cheap part and known failure point that I’d replace it anyway.


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## Jicafold (Mar 21, 2016)

It's fixed! I did the smoke test thing with a cigar. Took off a vacuum hose and blew into it. Strangely I didn't see smoke so much as hear a whistle. The problem was that one of the allen screws from the intake manifold block off plug that came with the PCV block off plate kit had fallen off. Small hole where the bolt was. Put a screw back in....test drive....all is well. Rock steady idle. Thank you for your help.


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## Thy_Harrowing (Dec 7, 2014)

Jicafold said:


> It's fixed! I did the smoke test thing with a cigar. Took off a vacuum hose and blew into it. Strangely I didn't see smoke so much as hear a whistle. The problem was that one of the allen screws from the intake manifold block off plug that came with the PCV block off plate kit had fallen off. Small hole where the bolt was. Put a screw back in....test drive....all is well. Rock steady idle. Thank you for your help.


Haha that’s a classy smoke test 

I’m about to go out and do axles. Wish I had a cigar to enjoy while at it. 

Glad it is fixed. After you reminded me it had rough idle I figured it had to a tiny vacuum leak that you would find eventually with a more thorough test. Nice work.


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## Jicafold (Mar 21, 2016)

Dude, Thank you so much. I mean I have skills but I am still learning from others with wisdom.. Now I have a fixed car and a cigar in my mouth while I change my DSG fluid. That was my next project and I am on schedule. Hope you have a great day.


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## Thy_Harrowing (Dec 7, 2014)

Jicafold said:


> Dude, Thank you so much. I mean I have skills but I am still learning from others with wisdom.. Now I have a fixed car and a cigar in my mouth while I change my DSG fluid. That was my next project and I am on schedule. Hope you have a great day.


No problem at all, glad it worked out for ya and hope the DSG fluid change goes well. I never owned a DSG so I don’t know about that but friend of mine said it isn’t too bad at all so you’ll be fine. Feel free to PM anytime you need some “wisdom”. I’m still learning myself (always learning, that’s how I like it) but I’ve tucked away a lot of info in my brain, some useful and some not so useful, over the years about these VWs so I can help out in most areas. Have a good one


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## JCMaler (Jan 8, 2003)

TSI GTI here w/ P0171 Fuel Trim; Bank 1 code CEL. Curious what function the brake booster hose does, as I have had a fluttering/vibrating /chattering brake pedal at idle, and while driving (especially evident when cold/cold out at a light, etc); feels like the ABS is triggering. I had the ABS module recall performed somewhat recently, so was assuming that problem was related... now I'm thinking this "brake booster hose" could be some sort of vacuum-related issue that could solve both problems.

https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/brake-booster-hose/5c0612041k/

Anyone have any experience with the Spulen silicone replacement hose?
https://www.uspmotorsports.com/SPULEN-2.0TSI-Brake-Booster-Hose.html


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## Thy_Harrowing (Dec 7, 2014)

JCMaler said:


> TSI GTI here w/ P0171 Fuel Trim; Bank 1 code CEL. Curious what function the brake booster hose does, as I have had a fluttering/vibrating /chattering brake pedal at idle, and while driving (especially evident when cold/cold out at a light, etc); feels like the ABS is triggering. I had the ABS module recall performed somewhat recently, so was assuming that problem was related... now I'm thinking this "brake booster hose" could be some sort of vacuum-related issue that could solve both problems.
> 
> https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/brake-booster-hose/5c0612041k/
> 
> ...



I do NOT believe your issue is related to a brake booster hose leak, I believe it is related to the brake system itself which can behave in many different ways when it is very cold that can manifest itself in pedal feel. While this is often physically related to the braking components if it truly feels like the ABS is triggering in your case then I would think it relates to the hydraulics. How cold is it there? The properties of fluids will change in extreme cold. When was the last full brake fluid flush?

Yes, I have the Spulen silicone hoses. They are great quality and a good thing to upgrade preventatively because eventually those brake booster hoses will crack. You could of course get similar hose for much cheaper instead of paying for the name but the nice thing about the Spulen hoses is they are molded to shape for the application.


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## JCMaler (Jan 8, 2003)

> I do NOT believe your issue is related to a brake booster hose leak, I believe it is related to the brake system itself which can behave in many different ways when it is very cold that can manifest itself in pedal feel. While this is often physically related to the braking components if it truly feels like the ABS is triggering in your case then I would think it relates to the hydraulics. How cold is it there? The properties of fluids will change in extreme cold. When was the last full brake fluid flush?
> 
> Yes, I have the Spulen silicone hoses. They are great quality and a good thing to upgrade preventatively because eventually those brake booster hoses will crack. You could of course get similar hose for much cheaper instead of paying for the name but the nice thing about the Spulen hoses is they are molded to shape for the application.


Thank you for the info! My issue isn't exclusive to very cold temperatures, although it does seem to make it worse. Temps should be similar in NY to PA. Obviously right now we're getting that major freeze :snowcool:. I'm the original owner of this 2009 so the pedal feel is not normal for any weather condition. It's possible it's hydraulic-related. I'd have to check my records, but last brake fluid flush was w/in the last year for the ABS-module/software recall; I initially thought this issue was related to that upgrade since it surfaced recently afterwards. I can plan to flush next warm-weather-day I get, to rule that out. Hoping to diagnose this P0171 code myself w/o a smoke test. I can live with the brake issue for now...

It looks like the Spulen hose reuses the plastic ends of the OEM hose? Are the ends a potential failure point? Mine are approaching 10 years old at this point; they're original at ~80k. Also, is the hose a one-sze-fits-all-TSI-application? the suffix is different to the ECS tuning part. I wonder if one of the pictures are flipped, because it looks almost like a mirror-image to the two pics (in the links) I provided. The Spulen is way cheaper than the OEM replacement, so already ahead of the game price-wise :thumbup: Do cracks usually develop along the length of hose under the metal heat shield on the original? I just did a dsg service a few weeks ago, would have been the perfect time to upgrade that hose while the BSH intake was off; that things a major PIA and I hate the silicone interface tubes; the clamps slip and leak (In earlier cause of my P0171 code). Gonna pull the car inside at work and poke around that hose to look for cracks, and the condition of the ends... Too damn cold to work on cars outside :snowcool::beer:


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## Thy_Harrowing (Dec 7, 2014)

JCMaler said:


> Thank you for the info! My issue isn't exclusive to very cold temperatures, although it does seem to make it worse. Temps should be similar in NY to PA. Obviously right now we're getting that major freeze :snowcool:. I'm the original owner of this 2009 so the pedal feel is not normal for any weather condition. It's possible it's hydraulic-related. I'd have to check my records, but last brake fluid flush was w/in the last year for the ABS-module/software recall; I initially thought this issue was related to that upgrade since it surfaced recently afterwards. I can plan to flush next warm-weather-day I get, to rule that out. Hoping to diagnose this P0171 code myself w/o a smoke test. I can live with the brake issue for now...


If the fluid was flushed within the last year then I wouldn't bother doing another flush, but I would do a bleed if the issue surfaced shortly after that work was done in case they didn't fully bleed the system. Bleeding after an ABS system change needs to be done FAR more thoroughly than a normal routine bleed. At a high level it involves using software to interface with the ABS control module and cycle it whilst bleeding. It needs to be done several times. I would certainly hope the dealer, of all places, knows that but if they were in a rush they may not have bled it thoroughly. I would start there. I you want to do it yourself you're going to need VCDS to perform the full bleed procedure including the ABS system... Do you have access to VCDS? 



> It looks like the Spulen hose reuses the plastic ends of the OEM hose? Are the ends a potential failure point? Mine are approaching 10 years old at this point; they're original at ~80k. Also, is the hose a one-sze-fits-all-TSI-application? the suffix is different to the ECS tuning part. I wonder if one of the pictures are flipped, because it looks almost like a mirror-image to the two pics (in the links) I provided. The Spulen is way cheaper than the OEM replacement, so already ahead of the game price-wise :thumbup: Do cracks usually develop along the length of hose under the metal heat shield on the original? I just did a dsg service a few weeks ago, would have been the perfect time to upgrade that hose while the BSH intake was off; that things a major PIA and I hate the silicone interface tubes; the clamps slip and leak (In earlier cause of my P0171 code). Gonna pull the car inside at work and poke around that hose to look for cracks, and the condition of the ends... Too damn cold to work on cars outside :snowcool::beer:


Yes, the spulen hoses reuse the plastic ends. No, the plastic ends are not a common point of failure, the hoses themselves are the common point of failure as they get brittle over time. I was gonna say they are usually pretty damn easy to spot but then I had to remind myself that with your TSI you have that metal heatshielding you mentioned over the hose. The FSI brake booster hoses don't have that. You're going to have to remove that to check for sure and at that point you may as well replace the hose because without that heatshielding it will definitely get brittle quicker. 

Let me just point out that I've had cracked brake booster hoses that did not impact my braking feel or power, oddly enough. The brake booster must do that good of a job with amplifying the vacuum it gets that even a fairly big leak doesn't sufficiently under-power it. That said, the brake booster hose routing is a bit different on the TSI than my FSI and so there may be some different behavior as far as the impact of a leak. It did however make my car idle like crap, as you would expect from a vac leak, so that's a telltale sign I assume you would have mentioned. Another reason I don't think you have a vac leak in the booster hoses. But, again, can't hurt to replace them with the spulen hoses anyway for future-proofing. Yes it should be one-size-fits-all for your TSI.

Yeah, it his 0 degrees today... I ain't doing **** on my car for awhile either. Even my propane heater struggles to keep my garage warm in this cold.


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## JCMaler (Jan 8, 2003)

I initially misread your question; I read '_bleed_' instead of "_flush_". Not sure what the dealership would have done for the ABS module and software update, I'm sure they had to cycle the pump whilst bleeding... good point about potentially rushing. I had called them a few months back questioning that something isn't right after the ABS recall service and two dealerships made it clear that all work would be on my dime. Last time I bled the brakes myself (2-3 years ago?...again, I need check my records) I believe I cycled through enough to replace all fluid in the lines, but didn't use VCDS, so I'm assuming that would be needed to replace the fluid in the ABS pump etc. I do have VCDS and a motive bleeder, but using the two together for a bleed/ABS-cycle will be a first for me. I'll look into it :thumbup:

Yeah, I plan to do the Spulen hose either way. I have an email in with USPmotorsports questioning the cross-reference numbers for the TSI hose as stated on their website ("_Replaces the following factory part# 1K0 612 041 FH, 1K0 612 041 GJ_"). These seem like FSI hoses; 5C0 612 041 K seems correct to me. I also questioned the same thing about reusing the VW plastic end connectors, which you answered :thumbup:


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## Thy_Harrowing (Dec 7, 2014)

> Last time I bled the brakes myself (2-3 years ago?...again, I need check my records) I believe I cycled through enough to replace all fluid in the lines, but didn't use VCDS, so I'm assuming that would be needed to replace the fluid in the ABS pump etc.


That's fine, you only need to flush out the ABS system when you are either doing work on the ABS system and exposing it so that air gets in, obviously, or if you manage to let the brake fluid reservoir empty because then air gets pulled into the system. So your flush back whenever you did it without using VCDS to cycle the ABS pump and do a full flush was fine. However, in the case you are in now, you're going to want to take that extra step since the dealership had done work on the ABS system and it is possible they didn't properly flush the air out of it. Ross Tech has procedures on how to do this on their site if I recall correctly. It is not complicated, just annoying.


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## JCMaler (Jan 8, 2003)

Thanks, I'll look into the Ross Tech procedures. One huge observation is that this annoying pedal vibration only happens when in gear. Anyone in the car can hear the thing actually chatter... I put it in neutral and it disappears.


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## Thy_Harrowing (Dec 7, 2014)

JCMaler said:


> Thanks, I'll look into the Ross Tech procedures. One huge observation is that this annoying pedal vibration only happens when in gear. Anyone in the car can hear the thing actually chatter... I put it in neutral and it disappears.


Okay see now that takes this whole thing in a totally different direction and would have been good to know in the first place... Before we continue, are there any other significant pieces of info like that which you haven’t brought up?


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## JCMaler (Jan 8, 2003)

I just made this observation over the weekend. There's no real-world reason for me to take my DSG car out of gear while at a red light (until now). It's not as obvious when first going from P into gear... but that's probably just circumstantial since I don't have my foot on the brake for any length of time then. 

The other weird "transmission/clutch"-related oddity is when it's cold I've noticed (only a handful of times) a "surge" or clunk when it initially "grabs"... it's tough to explain, but almost like you can't give it gas too early or it will have a bad lurching effect. These are all very recent observations... I've only experienced a "oh $#!t, that was bad!" sound/feel once... and that was last Friday. Also, not something that surfaced specifically after my DSG service. It's been my observation that all auto cars I've owned can feel "sluggish" going into gear or transferring that initial power when it's extremely cold out... so I hadn't considered this an issue... Thoughts?


Oh, and related to the Spulen TSI brake booster hose, I received this reply from USP Motorsports:

"_Hello,

From what I can see they are the same part https://www.vwpartsvortex.com/oem-parts/volkswagen-vacuumpipe-5c0612041k. I know our fitment on this product is well tested and correct. If you see your vehicle listed under the "cars this fits..." then this will be compatible for your vehicle._
...?


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## JCMaler (Jan 8, 2003)

Sorry this P0171 issue has gone off track to the OP. The smart money is on my brake pedal issue being related to my aftermarket air intake tube hitting the brake lines or reservoir...

https://forums.vwvortex.com/showthr...e-brake-pedal-vibration&highlight=brake+pedal

https://forums.vwvortex.com/showthr...through-the-brake-pedal&highlight=brake+pedal

https://forums.vwvortex.com/showthr...g-only-on-idle-Help&p=113045755#post113045755

https://forums.vwvortex.com/showthr...g-only-on-idle-Help&p=113045755#post113045755

https://forums.vwvortex.com/showthread.php?4575258-brake-pedal-rattle&highlight=brake+pedal

https://forums.vwvortex.com/showthr...-after-Neuspeed-install&highlight=brake+pedal

https://forums.vwvortex.com/showthread.php?4152735-Brake-Pedal-Shudder&highlight=brake+pedal

https://forums.vwvortex.com/showthr...elt-through-brake-pedal&highlight=brake+pedal

https://forums.vwvortex.com/showthread.php?3606683-brake-pedal-pulsating&highlight=brake+pedal

https://forums.vwvortex.com/showthr...es-at-idle-after-intake&highlight=brake+pedal


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## Thy_Harrowing (Dec 7, 2014)

Apologies for the delayed response, been a busy week here...



> I just made this observation over the weekend. There's no real-world reason for me to take my DSG car out of gear while at a red light (until now). It's not as obvious when first going from P into gear... but that's probably just circumstantial since I don't have my foot on the brake for any length of time then.


Fair enough, I did not recall if you had stated that you have DSG or MT and sometimes I mistakenly just assume MT because I have always owned MTs and that's just what my mind gravitates toward.




> The other weird "transmission/clutch"-related oddity is when it's cold I've noticed (only a handful of times) a "surge" or clunk when it initially "grabs"... it's tough to explain, but almost like you can't give it gas too early or it will have a bad lurching effect. These are all very recent observations... I've only experienced a "oh $#!t, that was bad!" sound/feel once... and that was last Friday. Also, not something that surfaced specifically after my DSG service. It's been my observation that all auto cars I've owned can feel "sluggish" going into gear or transferring that initial power when it's extremely cold out... so I hadn't considered this an issue... Thoughts?


I have no first hand experience with the DSG trans, only what I've picked up on forums and in discussions with friends. My only experience with owning an automatic is my truck but every other car I've ever owned has been manual... so with that little disclaimer, I tend to agree with your assessment that autos, in general, are sluggish when it is extremely cold. My truck definitely is more sluggish in the Winter, but it is also old and has over 240K miles on the original engine/trans so it's allowed to be haha. As long as you have the right gear oil in there and you're sure of that then there isn't much else you can do about that. Surges, clunks, and odd grabs can sometimes be a sign that you need to get a TCU software update as VW has come out with better flashes for the TCU over the years, but those symptoms could also just be related to the behavior of the trans in the extreme cold too. 

Now, as for your annoying pedal vibration... well, the statement you made about it only happening in gear and not in neutral did originally make me suspect something along the lines of bad trans mount or subframe/dogbone mount, bad enough that harsh enough vibrations are occurring so as to vibrate any pedals or parts in the front of the cabin. However, there are plenty of other possibilities that can exist when we're dealing with a noise occurring when in gear vs. in neutral because so many more factors in play when you're in gear. Your idea regarding the intake rubbing on the master cylinder is a good example because while in gear the engine and everything attached to it will lurch when getting moving from a stop and also when coming to a stop whereas it will not when in neutral naturally.

Additionally, intake tubes hitting the foremost line of the master brake cylinder are somewhat common which is why some intakes come with a bracket to suspend the tube more firmly and prevent this. The only thing I would call into question is why this only just started happening... how long has the intake been on before this started happening and did you remove/reinstall it during any work recently before the brake vibration began?



> Sorry this P0171 issue has gone off track to the OP. The smart money is on my brake pedal issue being related to my aftermarket air intake tube hitting the brake lines or reservoir...


I don't think you have to worry about going off-topic... the OPs subject was handled long ago and this is still an informative/productive conversation so it will benefit future readers regardless.

My recommendation is to create a home-made bracket for your intake tube. I've had to do this myself because I had the same issue you did years ago, and frankly forgot until you brought it up. I have long since forgotten exactly what sizes of hardware I bought to make my bracket but the gist of it is this: 

The TSI should have the same battery tray as the FSI so there should be a free bolt hole on the left side of your battery tray that is about 6 inches below and 2 inches to the right of the intake tube. Buy a long enough bolt with very wide washers (practically tubes) and then some any kind of hardware that can serve as a bracket arm with a bolt hole in it. Assemble the parts so that the bracket is supported by the big washer/tubes that run the length of the bolt and then thread in the bolt. I can't remember the thread type but I wanna say my bolt was an M6 x 1.0. That's a common thread on these cars.

Unfortunately I don't have many pictures where you can see it all that well but the below should give you an idea. The washers running along the bolt are a bit difficult to see as the black tape I put on them makes them blend in with the rest of the engine bay (which was intentional. There is foam tape around the bracket portion itself and then duct tape around that for better heat resistance, since the intake tube lays on that bracket; the foam tape helps cushion any sound and the duct tape keeps the foam tape from melting/deteriorating. It looks kinda fugly in the first pic but it's hardly noticeable with the intake laying on it so it doesn't destroy the aesthetics of your engine bay. I haven't had a single issue with pedal vibration since I put this in 4 years ago


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## JCMaler (Jan 8, 2003)

No need for apologies, you've been a great help and I really appreciate your detailed response(s)! I'll try to respond to your questions and feedback, but first an update... 

*The check engine light, and brake-pedal-vibrations are both gone! (for now)*

I have played with the [BSH "race"] intake tube a bit... first experimentally just by putting a rubber-band around the "jiggly" tube and looping it around the bracket that's against the firewall, just above the reservoir. It worked! Essentially, the tube was resting on the reservoir cap, right at the bend; the L-shaped tube essentially has one connection points at one ends, the other end just giving support (nothing clamping it), so it really does need a support in the middle. I've read people putting foam where contact is made; I think any contact between intake and brake components should be avoided. I know I'll need to re-seat the silicone intake boot(s) and also the intake "scoop" at the other end (as it rotates a bit) when I get more time/daylight... It's at the cone-filter end where the tube just rests in a cutout in the shovel-shaped scoop. Play inevitably develops...

So yesterday I also removed my under-hood insulation. It sags in the back, basically blanketing the intake... it was a little chewed up here. Also, the side tabs no longer stayed in place corresponding hood ovals, and it had begun sagging there also. I had concerns that this was trapping heat rising from the turbo-area also. It looks better without it, and no longer puts weight on the intake tube. I do however have to get used to the increase in sound. It actually sounds like an air leak... but that wouldn't explain the lack of CEL. Initial feedback; I don't like it without. From what I've read, people don't seem to notice any increase in sound, but I certainly do, as it makes me think there's something wrong. I wish I spaced out the two changes :facepalm:.



> The only thing I would call into question is why this only just started happening... how long has the intake been on before this started happening and did you remove/reinstall it during any work recently before the brake vibration began?


DSG service a few weeks back ... you have to take half the damn car apart lol, intake off, battery tray out... I finished in the dark; didn't pay too much attention to tube alignment/interference, like I did when it was new. My newest focus was actually getting the damn tube in the silicone boots, and have them stay in place when I tighten the clamp. I hate this. Wipe off oily residue before tightening, but they're still slippery and the clamps inevitable shift. Another reason in the past for my CEL's... maybe two months ago I had noticed the clamp actually slipped off; that fixed the CEL that time (again, didn't pay any attention to contact with other things). I want to delete the noise pipe simply so there's one less thing in the way when working down in there!!!!!!!!!! :banghead: I don't have small hands and this fiddly work gives me anxiety.

A few final points related to the brake pedal vibrations I had experienced... They happened in D and S only, not P, N, or P.

Thanks for the details regarding the support you made. I'm trying to dig up a pic of my intake to compare... I just want to post, and update later since photobucket has a tendency to crash literally everything...


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## Thy_Harrowing (Dec 7, 2014)

Sounds like you're narrowed it down and just need to figure out the best way to support that intake. My application is a bit different but the battery tray and intake positioning should be pretty close to the same so the bracket idea I shared should work. Your idea of just putting a sound deadener of some kind over the place the intake is hitting the reservoir works too, just keep in mind whatever you use must be pretty heat resistant.



> I do however have to get used to the increase in sound. It actually sounds like an air leak... but that wouldn't explain the lack of CEL. Initial feedback; I don't like it without. From what I've read, people don't seem to notice any increase in sound, but I certainly do, as it makes me think there's something wrong.


I don't know where you're reading people saying that they don't notice any increase in sound with the sound deadener under the hood removed but they must not be very observant people. Engine noise is absolutely increased with that thing removed and it is totally normal that you notice more. It is NOT normal if you think you hear an air leak sound (as long as you aren't confusing "air leak" with turbo noise?), but what IS normal is increased sound of general engine operation noise, especially injector ticking as the injectors on these cars are quite noisy.


Oh and about Photobucket... yeah it's complete trash. I used to use it but they switched over to a business model that includes paid accounts and the website design and responsiveness is abysmal if you have a free account. Or at least that's how it seems to me. They might have just lost all their good developers too and ALL service is bad even for paid accounts. Not sure which. But as a software developer myself I find their websites functionality absolutely awful. I've switched over to using Imgur to host photos on the forums and it is far superior. Just remember to set your photos/albums to private before you upload on Imgur so that they are only viewed by direct link (if you generate the BBCode link and put it on the forum post). Otherwise google drive is a super easy way to host and send share links to photos.


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