[doodlestj]

I would only guess at a small leak in the pipe work from the turbo through the intercoolers.
Can you rig up a pressure test through the pipe work to the throttle?
It sounds like you've had a few problems, so hopefully this is just the last one.
Do you still get the misfire error as well? Even though you've replaced the coil?

Yes I still get the misfire errors. I've not done a pressure test... honestly not sure how to do that. Could you link me to whatever product you use? I can probably figure out how to do a pressure test from there

 

[doodlestj]

You are definitely clearing the errors?

Yes I'm clearing the errors with VCDS every time

 

[doodlestj]

The ross-tech article.

Have you logged the car? The rosstech article is pressure drop between turbo and throttle body... so if you log it, you will see what the desired and actual boost is.... maybe the map sensor is at fault, when I had that error the DV was jammed open?

I assume all the other errors disappeared like the misfire?

Have you checked for splits on the left side (looking at the engine) on the inlet manifold leading up to the brake servo.

I take it there's no hardware hacks like resistors to try and fool the car into higher boost.

Sorry I'm a bit of a noob... this article http://wiki.ross-tech.com/wiki/index.ph ... 297/004759 ?
I'm not sure what you mean by 'logged the car.' Basically I can go in and find whatever code ross tech uses and it will show me boost and also what boost it should have
Haven't replaced the MAP sensor, I could try that.

No, none of the errors disappeared. I always get all 4 errors.

I've looked before for all types of splits/cracks... I'll go look again. And no, no hardware hacks

 

[doodlestj]

Okay so I looked for any cracks on the line from the intake manifold to brake servo, saw nothing

Tried to do a log: using this website https://www.ross-tech.com/vag-com/m_blocks/110-119.html
and group #115 (I think that's the correct one to use). Only saw actual pressure value sometimes exceed specified value by 10-20mbar

One thing of note, I logged group #030 for oxygen sensors and it appears sensor #2 is never active... maybe this is my issue?

 

[doodlestj]

I don't really know the vcds blocks.

But the o2 sensors are bank 1 sensor 1 and bank 1 sensor 2 you don't have a bank 2 as that is v6s

Yeah sorry I meant bank 1 sensor 2... It's never giving the readout "sensor ready"

But I do get "sensor ready" for bank 1 sensor 1

 

[doodlestj]

I don't think the post cat sensor does anything, mine is coded out for sports / de cat.

Is everything properly plumbed in?

Underneath the inlet manifold there's the two 4mm connectors for FPR and N249 (or straight to DV if N249 deleted) on the left and in the centre there's a bigger (maybe 6mm) connector which connects to the PCV valve.

I think if you run blocks 1, 31 and 32? You can view long term and short term fuel trims. And then if you clear all errors (even if there are none)? That will reset the fuel trims. If there's an air leak it will be easy to tell.

Hmmm so no sense in buying a new O2 sensor?

Yeah I just deleted the N249 (thought maybe there was a leak in there) and plumbed in my own lines from manifold to DV and manifold to FPR. Had the codes both before and after doing that. I've seen the PCV connector but can try to look at it more thoroughly. I'll try to look at blocks 1, 31, and 32 tonight after work

 

[doodlestj]

Don't discount the "P0420 Catalytic system efficiency below threshold" error being the Cat itself failing.

I got my V6 in 2013 and have been getting "16804 - Catalyst System; Bank 1 P0420 - 001 - Efficiency Below Threshold" errors intermittently, mainly if driven gently/cruising.

At the end of 2019 I purchased a Scorpion system and Lucifer SportsCats, with the intension of fitting them after its Feb 2020 MOT... but with the :roll: situation in 2020 I only got round to fitting them last Friday.
When we got the old Cat off we could see a hole down the centre of the Bank 1 Cat........!



Explains why it only just got through the last few MOT emissions tests too... :lol:

Ouch. I hope that's not my issue, sounds expensive. I also don't get why that would cause misfires too, though

 

[doodlestj]

I don't think the post cat sensor does anything, mine is coded out for sports / de cat.

Is everything properly plumbed in?

Underneath the inlet manifold there's the two 4mm connectors for FPR and N249 (or straight to DV if N249 deleted) on the left and in the centre there's a bigger (maybe 6mm) connector which connects to the PCV valve.

I think if you run blocks 1, 31 and 32? You can view long term and short term fuel trims. And then if you clear all errors (even if there are none)? That will reset the fuel trims. If there's an air leak it will be easy to tell.

Running blocks 1, 31, and 32 it seems my lambda stays pretty close to 1. Not sure how to view long or short term fuel trim

Group 32 I don't really understand... it says my bank 1 sensor 1 idle is about 2.6% and my bank 1 sensor 1 partial load is -7%... no idea what to make of these #s

Attached the log for those blocks

 

[doodlestj]

I still don't understand about the errors not disappearing?

Have you cleared them with the engine off and made sure they are not there. And they only come back after a few minutes running?

Did you check the fuel trim blocks 31 and 32 I thing sort term and long term..

The coil wiring can go brittle and / or dodgy earth connectors on cam cover..

I clear them and then they come back but not for some time... sometimes after 40kms of driving, sometimes up to 250kms later

 

[doodlestj]

I had a cheap coil pack and it vibrated up the tube leading to an occasional misfire.. I also bought some bkr7s from ebay and one of them cylinder 1 failed, it would only miss like a lul if hot and ~5500rpm..

If its intermittent is it possibly wiring? Or maybe oil getting into the spark plug hole? From the centre cam gasket..

Could be wiring. Tracing that back is going to be a bitch.

I saw there was a bunch of oil on the spark plug so I replaced the valve cover gasket... haven't checked since I did that but I assumed that fixed it

Just replaced the downstream O2 sensor :/. If the code comes back I'll order some new PCV pipes and an intake manifold gasket and try replacing that. Unfortunately shipping takes a long time

 

[doodlestj]

Still getting the codes... going to take it apart a bit and order new PCV hoses today. Pretty hard to find online... if you have any recommendations on places to shop for them I'll take any advice.

Will probably replace the intake manifold gasket while I'm at it

 

[doodlestj]

I don't think the post cat sensor does anything, mine is coded out for sports / de cat.

Is everything properly plumbed in?

Underneath the inlet manifold there's the two 4mm connectors for FPR and N249 (or straight to DV if N249 deleted) on the left and in the centre there's a bigger (maybe 6mm) connector which connects to the PCV valve.

I think if you run blocks 1, 31 and 32? You can view long term and short term fuel trims. And then if you clear all errors (even if there are none)? That will reset the fuel trims. If there's an air leak it will be easy to tell.

Running blocks 1, 31, and 32 it seems my lambda stays pretty close to 1. Not sure how to view long or short term fuel trim

Group 32 I don't really understand... it says my bank 1 sensor 1 idle is about 2.6% and my bank 1 sensor 1 partial load is -7%... no idea what to make of these #s

Attached the log for those blocks

Sorry it is 32 and 33 not 31 and 32

Essentially, if you are leaking air you will get fuel trims out side the target range...

There are some other linked videos, essentially the goal is 0%, long term fuel trims are adaptions based on how much more or less fuel is required to correct for unmetered air (a leak) as idle is always at vacuum. But there are acceptable settings. Like maybe 4% for long term and -10 to +10 for short term. If you have -2.6 in LT and clear all errors (even if none) fuel trims are reset and then looking at ST FT your short term might be -10,+7,'-10,+7.... etc then after a while the LTFT might be -1 then your STFT should be -9,+8,-9,+8... etc. Short Term always go less, more,less,more but its ideal to get the gap between the numbers smaller..

There's also a Map table called FKVVS which stores a profile based on Audi Stock Injectors, but that sometimes needs adjusting... there's a tool you can get to tell you the best new values, it's based on the throttle position (maybe load?) and revs, and you drive around trying to cover as many rpm, TP combinations and it will show you the adjustments for your table..

Thank you! This helped a lot.

So I'll update as this progresses but my LT FT seems to be around +2%... not enough to throw a code. ST FT hovers around +/- 2%. So nothing crazy there

HOWEVER the good news is that I was spraying starter fluid around the engine bay and measuring ST FT while doing so. I found spraying it right on the PCV caused a spike to around -20% ST FT. So I ordered some parts to replace the PCV hoses. Supposed to ship here by Friday, surprising how fast that is

Also, the code for the pressure drop between turbo & throttle body registers almost immediately after a reset. The other 3 can take a while to materialize

Thanks again for the help Stuart, I'll update you as I go. Hopefully will replace all PCV stuff this weekend and the intake manifold gasket while I'm at it. Was thinking perhaps since the LT FT seems normal that maybe my fuel injectors are just not dumping enough fuel? Or the cat is bad? I'll wait until after replacing the PCV to assess

 

[doodlestj]

Do you have access to an air compressor?

I have a 3D printed boost test adapter you are welcome to borrow to do a proper pressure test.

It'll probably work with a decent bike pump or foot pump too.

Drop me a DM.

Hey tried to direct message but it won't let me because I'm too new to the forum.

Anyway, I do have an air compressor and also a 3D printer. If you link me to an STL I can print it and hopefully figure it out from there

 

[doodlestj]

Well this weekend I took my intake manifold off. Replaced all PCV hoses (where I thought there might be an air leak) and the intake manifold gasket

Still have the same check engine lights:

-P1297 Pressure Drop between turbo valve and throttle body (Check DV!)
-P0300 intermittent misfires all cylinders
-P0303 misfire cylinder 3

EXCEPT this code: -P0420 Catalytic system efficiency below threshold (running lean)

Has changed to this code1136 Fuel Trim Bank 1 (add) system too lean

And now my LT FT is more like 6.4%... Damn it

Not sure what to do now. Going to do some more spraying around. Maybe replace the fuel injectors?

 

[doodlestj]

In other news my Rosstech vc scope seems to not work anymore. Not sure why. The graph function displays the value and individual gauges work but the vc scope won't plot them along the screen of the graph as time goes on

 

[doodlestj]

Thanks for the replies gents. When I was replacing the PCV system I think one of the other hoses just came a little loose and that was the big leak. Fixed that but still getting all the codes

When I spray starter fluid around the engine bay I can get ST FT to drop to like -7%... nothing as crazy as it was before. I will look at the FPR to see if it's clogged

And is there any way for me to tell if my fuel injectors are bad before just buying new ones? I don't see any measurement blocks that show me a volume of fuel injected

 

[doodlestj]

Fuel pressure regulator looks clean so far as I can tell

One thing of note - while trying to diagnose all this I deleted the N249 system. As a result of that I had to route a hose off the secondary air injection to the intake manifold so I teed it off to the hose that goes from the manifold to the FPR... I read to do that online. I don't think that's my problem because I had the codes before and after doing that

Any other ideas on where to route the secondary air injection hose to? When I just capped it off I got a separate, unrelated code so that doesn't work.

 

[doodlestj]

Measured the resistance of all the fuel injectors.. all were 12.5 ohms, right on spec

Took hose off the FPR while engine was running, it's definitely got suction. No fuel dripping out of FPR

Could be a leaking o-ring at the fuel injector? I need to get a fuel pressure gauge and check that

 

[doodlestj]

Got a fuel pressure tester, here are the results:

Turned the key to 'on' but no ignition. Fuel pressure held right at 40 PSI. I let it sit for 10 minutes and no drop.

With ignition on fuel pressure was about 35 PSI. Held that at any steady RPM. And if I blipped the throttle the fuel pressure would blip accordingly

To test if the fuel injector O-rings were leaking was 10 minutes enough time? Or should I let it sit longer?