18619/P2187/008583 - Bank 1; System too Lean at Idle

[MagicMK]

Hello - long time member that has been dormant for a while, but just had an issue that I'm having some trouble resolving. My Autel scanner tells me that "System too lean at idle, Bank 1." I cross referenced it with the RT page that provides the same data as my Autel (ie - check MAF, intake leak, exhaust leak, N80 valve, injectors, fuel pump). I just changed my N80 to remove it from the possible mix, and no luck there. The MAF was replaced about a year ago with an OE Hitachi MAF, and MAF has less than 10K on it. I even bought a new intake duct as my old one required zip ties for a tight hold. Oh, and the PCV valve and even updated metal breather hose (both genuine VW parts with lifetime warranties from FCP Euro). The air filter is newer as well, with less than 15k miles on it.

Now, one thing I have to check, as I haven't been under the car, yet, is that intermediate exhaust "tube" that connects the intermediate pipe with the rear mufflers. I have two muffler clamps on that, and it has come loose in the past... but it usually accompanied with some additional louder noise. And to cover some basic questions - my cam follower has been replaced multiple times (always in great condition), I use synthetic 5w-40 oil, and the car is closing in on 100K miles, and on the original timing belt.

EDIT - oh, and just realized it's not under my avatar... I own a manufactured in May 2008 VW GTI MKV with the BPY engine code and a timing belt.

Thanks in advance!

 

[GTI's]

FSI or TSI

Did you check the brake booster vacuum hoses?

A leak after the O2 sensors will not come in to play for Dtc.

 

[ROH ECHT]

I assume it is FSI since you mentioned it does have a belt?

Best thing to do is check for leaks. You can smoke it to test for leaks...or use a blower sealed as best you can into the intake. Then use soap & water in a spray bottle to spray all tubing and connections between the turbo and intake manifold. Remembering the two tubes to the pcv as they may be cracked or not connected fully and may have failed o-rings. Inspect what GTI's suggested as well as all of the EVAP tubing.

If all of this reveals nothing, then....I've seen on forums when a new B1S1 O2 sensor fixed this code. And again when one car sat at my VW dealer shop for a week while they found nothing wrong but tried everything.

 

[MagicMK]

FSI or TSI

Did you check the brake booster vacuum hoses?

A leak after the O2 sensors will not come in to play for Dtc.

Thanks - as part of my forum research, I found the other case where someone else found his brake booster hose practically "fell apart in his hand." As far as I can tell, the hoses going to the brake booster are in good condition. I was just under the hood the other day trying to find the location of my canister purge valve and I was checking out most everything with a hose connection. Btw, I finally found the valve on the lower left side of engine... it was quite difficult to locate the part, and nothing online or in YouTube seemed to mention the part (but, as part of the emissions system, I thought it was worth replacing - not a cheap part, though, at $44 for the Pierburg valve). Again, though, I haven't been able to locate any bad hoses.

 

[MagicMK]

I assume it is FSI since you mentioned it does have a belt?

Best thing to do is check for leaks. You can smoke it to test for leaks...or use a blower sealed as best you can into the intake. Then use soap & water in a spray bottle to spray all tubing and connections between the turbo and intake manifold. Remembering the two tubes to the pcv as they may be cracked or not connected fully and may have failed o-rings. Inspect what GTI's suggested as well as all of the EVAP tubing.

If all of this reveals nothing, then....I've seen on forums when a new B1S1 O2 sensor fixed this code. And again when one car sat at my VW dealer shop for a week while they found nothing wrong but tried everything.

Thanks for the suggestions - I saw some of your other posts that had some very good info. What tubes to the PCV are you referring? I just replaced the PCV about a year ago with an genuine VAG part, and at least at the time, don't recall noticing any issues. I also purchased a new gasket with the new PCV. As for the B1S1 02, is that by chance the 02 near the firewall behind the air box? I've already replaced 2 of my 02 in the downstream exhaust, but I was looking at that wondering what the lifespan on the part was. It's a real PITA for me right now as I'm past inspection, and am at a bit of a loss... was hoping the N80 and the new airbox connecting tube might have solved it, but no such luck.

A vacuum leak seems to be the normal culprit, but what about lack of fuel due to a dirty fuel filter? I ordered a new MANN fuel filter as well, as I've never changed the stock OEM filter, and I've had the car since it had 20k miles on it. So, I can comfortably presume that fuel filter has about 100K miles on it. Again, though, I am wondering about that one 02 sensor. Do you know the expected life span on that 02?

Btw - is this the part you mean when you write B1S1 02? -- https://www.fcpeuro.com/products/audi-volkswagen-vw-oxygen-sensor-front-bosch-17045#reviews

Thanks.

 

[GTI's]

You may want to take a look at the hoses again hard to believe with over 100k you have never had them replaced, they usually will split at the barb fittings and is sometimes hard to see. These are from my car with less than 50k/12yrs

 

[MagicMK]

You may want to take a look at the hoses again hard to believe with over 100k you have never had them replaced, they usually will split at the barb fittings and is sometimes hard to see. These are from my car with less than 50k/12yrs

Interesting - I will take a closer look with some powerful lighting, but did not notice any apparent cracking on first look.

 

[ROH ECHT]

Thanks for the suggestions - I saw some of your other posts that had some very good info. What tubes to the PCV are you referring? The two large corrugated tubes. One goes form the PCV to intake manifold and the other down to the oil filter housing. I just replaced the PCV about a year ago with an genuine VAG part, and at least at the time, don't recall noticing any issues. I also purchased a new gasket with the new PCV. As for the B1S1 02, is that by chance the 02 near the firewall behind the air box? Yes, it's that one which measures air/fuel and reports rich or lean to the ECU. I've already replaced 2 of my 02 in the downstream exhaust, but I was looking at that wondering what the lifespan on the part was. It's a real PITA for me right now as I'm past inspection, and am at a bit of a loss... was hoping the N80 and the new airbox connecting tube might have solved it, but no such luck.

A vacuum leak seems to be the normal culprit, but what about lack of fuel due to a dirty fuel filter? It could be, but if so...it would likely run poorly (i.e.; backfire, pop, power cut etc.) when you get aggressive with the throttle if the filter is plugged or fuel delivery in general is reduced. I ordered a new MANN fuel filter as well, as I've never changed the stock OEM filter, and I've had the car since it had 20k miles on it. So, I can comfortably presume that fuel filter has about 100K miles on it. Again, though, I am wondering about that one 02 sensor. Do you know the expected life span on that 02? It varies. I've replaced my B1S1 between 110k to 130k miles.

Btw - is this the part you mean when you write B1S1 02? Yes, that's the one. Replace it if you find nothing else wrong. -- https://www.fcpeuro.com/products/audi-volkswagen-vw-oxygen-sensor-front-bosch-17045#reviews

Thanks.

On some of the small tubing, visual and feel are good for inspecting them...but try disconnecting one end and use for example a bicycle tire pump with a tapered nozzle (if not able to access regulated compressed air) and have someone hold the pressure in the tubing while you spray them and look for bubbles to form. Otherwise, you may be prematurely replacing bits. Both GTI's and I are saying be sure to eliminate the possibility of any leaks first. Unless you are set on doing so because the parts are old anyhow. Just to repeat, there could be a poor seal anywhere between the MAF and intake manifold...including the MAF-to-intake seal.

 

[GTI's]

If you have Vcds or other scan tool that can look at fuel trim you can also us hydrocarbons to look for you leaks.

 

[MagicMK]

On some of the small tubing, visual and feel are good for inspecting them...but try disconnecting one end and use for example a bicycle tire pump with a tapered nozzle (if not able to access regulated compressed air) and have someone hold the pressure in the tubing while you spray them and look for bubbles to form. Otherwise, you may be prematurely replacing bits. Both GTI's and I are saying be sure to eliminate the possibility of any leaks first. Unless you are set on doing so because the parts are old anyhow. Just to repeat, there could be a poor seal anywhere between the MAF and intake manifold...including the MAF-to-intake seal.

Hey, thanks again - just wanted to advise, I'm still working on this (just haven't had enough time to dedicate to fixing). I've checked that tube, but I see your pic shows this sort of t connection to the tube, but I do not recall seeing that next to master cylinder / firewall. I'm not clear where that t connection is at... is that on the other end of tube since you have the tube cut? As an FYI, I did order the other 02 sensor on the firewall (I think I've replaced the other 2 on the car - I know I've replaced at least one, but likely both in the downstream exhaust under car). Ended up using Rock Auto for that, as FCP was over $20 more. I love FCP's warranty, but this is a 100k mile part, so not worth the additional money to buy from FCP for that part. I have my fingers crossed that this will fix the problem, but if it doesn't, then I'm going to invest more time in checking for split tubes and leaks (I've already been looking, but haven't found anything so far).

I'll keep you both updated.

Thanks.

 

[MagicMK]

Hey, you and ROH were dead-on as far as the causes go... but it turns out that you were dead-dead-on. So, I did order a rather expensive upstream O2 sensor, as the lifespan on those is only listed at about 100k miles, anyway. Even if it wasn't the issue, I figured it was at the end of its lifespan and may already be having some air reading accuracy issues. Also, that replacement is rather easy to do. So, next, after your comments, I was watching YouTube videos from the Humble Mechanic and Deutsche Auto --- the Deutsche video helped show that the part was located near the HPFP (didn't realize that!... I was looking near the firewall, on and near the brake booster), and Humble Mechanic went through a bit of a step-by-step discussion on how to diagnose lean codes.

Humble Mechanic mentioned the upstream O2 (which I'm also replacing) is often a culprit, but so are vacuum leaks. He also explained why airflow leaks prior to the MAF won't trigger a lean finding (already realized that, but helped to further drive it home by demonstrating how the ECM compensates by increasing fuel delivery by up to 25% due to the lean reading that is often due to a vacuum leak resulting in additional air picked up in the fuel mix that is read by the upstream 02 sensor as a "lean" condition). All of that said, when I went back out to look for this part next to the HPFP, I quickly noticed some small cracks. I then went to wiggle the hose closest to the top of the engine, and found that the other side had a much larger split in it! You were dead on right about me having 100K and it being odd if it was NOT cracked. Big thanks for that.... so, I took a quick look on FCP and a couple other sites, and found that FCP had about one of the best prices for what is really an OE part. As usual, the VAG part is really expensive, but they had a made in Germany Vaico for only $35. I was wondering why it wasn't listed as an OE part, so looked a little further and noticed it's exactly the same as the "OE" VNE part that's only $27.99, but on back order! So, basically, VNE Gmbh of Germany (Volker Natorp the founder) is the OE manufacturer for VAG at only $28... Vaico resells the part for a $7 markup at over $35, and VAG resells it as "Original VW" for $83 on FCP (although ECS has it for $69). I don't know how interested you find all of that, but I thought I'd share!

So, I used some 3M electrical tape around the split hose (for now) and will order a replacement part (along with an OE Mahle air filter) to get the free shipping - to hopefully fix this issue for good.

Thanks, again to both of you - and I'll follow up once I've tested the fix-es.

Btw, here's a link to that back ordered VNE OE part (with lifetime warranty from FCP no-less) for only $28:
https://www.fcpeuro.com/products/audi-vw-brake-booster-vacuum-hose-vne-1k0612041gm

 

[GTI's]

Did you checked the rear booster hose that connects to that front section by way of the coolant flange vacuum pass-through pipe and it was intact?

 

[MagicMK]

Did you checked the rear booster hose that connects to that front section by way of the coolant flange vacuum pass-through pipe and it was intact?

I'm not sure what part you're referencing... this part was clearly cracked and it has probably been cracked and leaking air for some time (over a year). The crack just got bad enough to trigger a CEL. What rear booster hose are you referencing? Again, this part was clearly leaking... I erased the code and ran it about 30 miles or so. I'll have to check it in the morning to figure out if it's in emissions "ready" status so I can run it over to the garage that's supposed to do my inspection. I can check that other hose (although, again, not clear which one you're referencing) -- but I'm guessing this was the culprit.

 

[GTI's]

Ok so you are replacing the one in the front of the system, the one you posted in the link above from FPCeuro. I am referring to the rear section from the brake booster to the pass-through pipe on the coolant flange side of cylinder head that then connects to the one you posted. Its the one I posted in the first pic in post #6 just that single hose from booster to pass-through pipe.

FWIW they do have a kit to replace most of the plastic pipes with silicone https://www.uspmotorsports.com/SPULEN-2.0T-FSI-Brake-Booster-Hose-Kit.html

& you can set readiness in the driveway with the proper scan tool without driving the car.

 

[MagicMK]

Thanks - yeah, that's the fitting I checked originally near the master cylinder and on the brake booster. That fitting looks great, and my braking performance has been great as well (albeit, I lost anti-lock some time ago). So, that fitting is not an issue for me. As far as setting readiness without driving, okay, you've piqued my interest. I don't have RT, but I do have an Autel MX808. It's funny, but I have an older Innova (a good one) that does OBD I as well, and has the connectors for it -- and it uses a proprietary "readiness" with a green, yellow, and red light set up on front of device. I've been using that to determine readiness vs the Autel, as I'm not aware where the hell the info is on the Autel. So, do you know if I can manipulate a field on the MX808 and set it as ready for emissions? The good news, though, is that I still have no CEL re-appearing after all of that driving, yesterday. I'll have to verify it's "ready," but it does look as though the tape may have worked.

Thanks.