Help: WOT Pre-Detonation / Knock + Oil Consumption

[Low and Behold]

Ive done research at nauseam for about 9 months. Hell I’ve also seen a couple guys with similar issues lately (@danaldson, @hemantpd1). But I feel like I’ve gone through the entire checklist of possible scenarios here, so its time to ask for some help.

The Car:
07 2.0 Avant (tip). 81k

The (short) backstory:
About a year ago I had my tune installed (GIAC). About a month later I started noticing some pre-detonation, and I was adding a quart about every 900 miles on average. Did my timing about 6 months ago and noticed a CRAZY amount of oil coming out of the IC piping. Ever since then I've been trying to find the source of it. At WOT I will get some hesitation. If I'm really gunning it at low RPM, I will usually get some knock as it builds boost. The car runs perfectly otherwise.

My theory:
The large amounts of oil in my IC piping is being sucked through the intake, causing hesitation, smoke, and ultimately pre-detonation/knock.

Things I've replaced over the past year:
MAF
Coil packs
Plugs every 3k (NGK coppers)
Entire PCV system
VC+VCG
Switched over to a BSH Catch Can
TURBO

Am I missing something major? Im sure I left something out - its a lot to remember. Im confident that the pre-detonation is due to the oil being sucked through. Just need to figure out how the hell the oil is making it in there.

[aluthman]

How much oil are we talking here? A small amount is normal. And when you say pre-detonation/knock, how are you determining this? Is it audible or are you looking at timing pull on logs?

[Low and Behold]

- About 1/3 quart
- Audible and verified by local tuning shop. Basically a loud ticking noise accompanied by smoke and loss of power

[Okedokey]

subscribed

[Okedokey]

What is your compression like?

[ShelbyM3]

We haven't tried a compression test. Our theory is that because the oil is pooling in the IC pipes so heavily, that even if the rings were bad, which I don't think they are, the oil will never make it to the IC pipes.
After we replaced the turbo, all was well for about 2 weeks. Now he's got a decent amount of oil back in the IC piping.


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[grassrootz]

subscribed.

[derrek]

compression test just so you know where you're at then check the valve cover for cracks on the underside.

[ShelbyM3]

Valve cover has been changed.


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[Low and Behold]

Compression test coming soon. I highly doubt the rings are responsible, but I want to know what the compression looks like anyways. I don't think its possible (and correct me if I'm wrong please) for bad rings to cause oil pooling in my intercoolers.

Im leaning back toward Valve Cover and PCV system and i have a question about the metal breather hose connected to the turbo: Is it supposed to let oil into the turbo from the valve cover? Mine seems to be letting in a good amount, and over the course of 800-900 miles I feel like it could really add up. mind you I've already replaced this breather hose once with the revision/check valve hose.

Heres a pic

[onedumslack]

My oil consumption ranges about 1 qt every 1500 miles. And it builds up in the intercoolers just like you have pictured. I have also replaced everything you have and got about 175 compression on all cylinders. I am not aware I have any knocking or pre detonation though. I eventually just gave up chasing the oil loss.

[Low and Behold]

My oil consumption ranges about 1 qt every 1500 miles. And it builds up in the intercoolers just like you have pictured. I have also replaced everything you have and got about 175 compression on all cylinders. I am not aware I have any knocking or pre detonation though. I eventually just gave up chasing the oil loss.

Are you tuned?

I honestly don't care much about the oil loss, but it seems to be causing performance issues. If i wasn't suffering from performance issues I would probably give up as well.

Can anyone shed some light on the metal breather tube pic i posted above? Really wondering if that could ultimately be causing the issue

[onedumslack]

Are you tuned?

I honestly don't care much about the oil loss, but it seems to be causing performance issues. If i wasn't suffering from performance issues I would probably give up as well.

Can anyone shed some light on the metal breather tube pic i posted above? Really wondering if that could ultimately be causing the issue

I'm Apr stage 2+ tuned. I got to the point where I needed to do a leak down test to determine if it's rings or valve guides and then lost interest cause I don't believe it's hurting my performance and I'll be engine swapping soon anyways.

[ShelbyM3]

Are you gonna do a compression test?


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[Low and Behold]

Update, in case this helps anyone -

Took it to a local tuning shop for further diagnosis. They were quite confident that oil filter housing was failing. There were no leaks whatsoever, but apparently it wasn't separating air/oil and just pushing tons of oil up to the VC - through PCV - Through rear breather (see post #10) - into intercoolers - up through intake. A gulp of oil through the intake will basically cut fuel octane and make it run like shit regardless, especially with a tune.

Changed it over the weekend. Most say its a PITA, but I found it surprisingly easy and relatively cheap at $185.

Car feels good right now. Still some slight pre-detonating as residual oil works it way out. Will take the ICs out this weekend to inspect and clean.

[Low and Behold]

Another update in case this can help anyone in the future. The saga continues...

No luck with that oil filter housing. Shop also recommended replacing the valve cover (again) so i did that this weekend with a brand new one. The old one was definitely thrashed so this should help. I also removed the ICs and all piping to deep clean everything and ensure there was no oil (or at least very little) left in the system to get sucked through the intake. Also put in new OE plugs. Still have the same issues with preignition

At this point I've decided that I'm definitely chasing TWO issues. I believe the oil consumption issue will now be solved with my third VC. There was no doubt that the old one failed big time after removing it and inspecting it. However, the preignition continues even with all the aforementioned work.

Now I'm starting to wonder if its just not getting enough fuel under boost? Cam follower was changed 8k ago and the old follower looked great. I think its time to refocus my efforts

[Jake@JHM]

Another update in case this can help anyone in the future. The saga continues...

No luck with that oil filter housing. Shop also recommended replacing the valve cover (again) so i did that this weekend with a brand new one. The old one was definitely thrashed so this should help. I also removed the ICs and all piping to deep clean everything and ensure there was no oil (or at least very little) left in the system to get sucked through the intake. Also put in new OE plugs. Still have the same issues with preignition

At this point I've decided that I'm definitely chasing TWO issues. I believe the oil consumption issue will now be solved with my third VC. There was no doubt that the old one failed big time after removing it and inspecting it. However, the preignition continues even with all the aforementioned work.

Now I'm starting to wonder if its just not getting enough fuel under boost? Cam follower was changed 8k ago and the old follower looked great. I think its time to refocus my efforts

Yea I don't see how an oil filter housing would lead to anything other than an oil leak.

Since you have an FSI car there is a chance you have a failing injector. If the injector is spraying less fuel than it is supposed to, that cylinder heat is going to get way hotter than the rest (lean), thus causing pre-ignition. If the injectors is CONSTANTLY spraying, its going to create severe hot spots in your combustion chamber that would cause pre-ignition and could lead to melting through the piston.

Additionally, both of those could cause your ring gap to expand in that cylinder which can cause cylinder wall scoring and ultimately leading to oil consumption.

[Low and Behold]

oil filter housing - suggested to be replaced by shop. Wasn't leaking, but they thought it might not be separating air/oil and just pushing it all up to the VC. I figured it was worth a shot at that point...

The consumption of oil lies pretty exclusively in my ICs and related plumbing. Correct me if I'm wrong, but bad rings won't put oil into this system? But given the busted seams in my old VC, it was obvious that the PCV was sucking oil straight out of the crankcase and forcing it down into the turbo.

The injectors are a good callout. I was originally thinking HPFP

[Jake@JHM]

oil filter housing - suggested to be replaced by shop. Wasn't leaking, but they thought it might not be separating air/oil and just pushing it all up to the VC. I figured it was worth a shot at that point...

The consumption of oil lies pretty exclusively in my ICs and related plumbing. Correct me if I'm wrong, but bad rings won't put oil into this system? But given the busted seams in my old VC, it was obvious that the PCV was sucking oil straight out of the crankcase and forcing it down into the turbo.

The injectors are a good callout. I was originally thinking HPFP

Oil in the turbo/intercooler is somewhat natural for a journal bearing turbo. Blow by is always going to be present. If it was super excessive then I would look at failing; valve cover, turbo chra, or pcv.

If you are down a quart, you would need to find about a quart or more worth of oil in your intercooler.

What was your though for HPFP? If that was failing you would have a fueling codes. The reason why a failing injector could slip under the radar is that AFR and EGT isn't monitored per cylinder.

[Low and Behold]

Mini bump.

Jake - you were correct on the fueling thought. But theres something Im a tad confused about after taking it to a local shop. After logging the car, they concluded that my fuel pressure is too low @110 mbar. They said it should definitely be higher and that its likely causing it to run lean to the point of preignition... They asked if I've changed my cam follower and inspected the cam. Yes, i have (7k miles ago). I can't recall EXACTLY what the follower looked like, I was just relieved that it didn't have a hole in it and wasn't caved in. They're willing to wager that i need a new cam.

Anyway, i ordered an HPFP stud kit and a new follower as i will check this weekend. If all looks good then ill be back to square one . I might just remove my tune (I don't have a stock program) if everything looks good. Id rather drive bone stock and not explode

Whats the high fuel pressure supposed to be at? They claimed that it should be 125, but i can't find anything to confirm it. Everything i find says 110 exactly.

[p0isin]

I thought 110 - 115 bar was normal for a stock tune. You shouldn't see large impact to lambda unless you are >15 bar too low on fuel pressure anyways as the ecu should increase injector open time to compensate. Log actual vs requested fuel pressure to see.

[Jake@JHM]

110 is correct for a stock car.

[Low and Behold]

Well the tune is asking for 120 so theres the issue. Grrr....

might just replace the follower and reinspect the cam. if all looks good then the tune will have to be removed

[Low and Behold]

Just for reference, whats the OEM hpfp capable of in terms of pressure?

[p0isin]

Maybe I missed it just skimming this page of your thread but is the car stock or tuned? A tune can request 120+ bar and some of the early b7 a4s had a PRV valve around that number which would cause it to open and dump fuel pressure too early.

[Low and Behold]

Maybe I missed it just skimming this page of your thread but is the car stock or tuned? A tune can request 120+ bar and some of the early b7 a4s had a PRV valve around that number which would cause it to open and dump fuel pressure too early.

Its ok to skim

Yes i am tuned - GIAC

[Okedokey]

What about modding the PRV to a RS4 one to increase the rail pressure capacity. Also, S3 injectors?

[Low and Behold]

Ive thought of this, but wondered why the stock PRV isn't putting out more pressure in the first place.

[martin0079]

Check LP fuel pressure at WOT. Make sure you are getting the 6bar. The relief valve opens if there is too much pressure on the HP side. Without seeing the log no one on here can say if the PRV is lifting causing you to stay at 110bar. IIRC and someone correct me if this isn't correct early 2.0t PRV was 116bar late was pushed to 120bar and the RS4 is 125bar.

No mention of carbon cleaning with the amount of oil in the intake you more than likely need to get this done. Also any pressure testing of the intake system vacuum leaks cause these kinds of problems.

[Jake@JHM]

Check LP fuel pressure at WOT. Make sure you are getting the 6bar. The relief valve opens if there is too much pressure on the HP side. Without seeing the log no one on here can say if the PRV is lifting causing you to stay at 110bar. IIRC and someone correct me if this isn't correct early 2.0t PRV was 116bar late was pushed to 120bar and the RS4 is 125bar.

No mention of carbon cleaning with the amount of oil in the intake you more than likely need to get this done. Also any pressure testing of the intake system vacuum leaks cause these kinds of problems.

Early 116bar
Late 126bar
RS4 136bar

[Low and Behold]

So my tuning shop here is certain that i need a new intake cam.

We think that the PO had a blown follower (for who knows how long), replaced the follower, but damage was likely done at that point. So this got me thinking...

I called my local Audi dealership so they can verify the cam/hpfp warranty. Im still within the timeframe and only have 85K. The service writer told me that if I'm having fueling issues i can pay them to inspect the pump, and if they find a hole in the follower everything will be replaced under warranty. Problem is I replaced my follower about 8-10k ago so I doubt its warn through, but who knows. I will check it on saturday.

If I see cam damage but the follower is ok, I'm going to find a blown follower and slap it on there, drive to audi, and ask them to inspect. I will have to uninstall my tune first for sure though

If any of the previous posters have thoughts on this let me know. Ive read through the extended warranty thread and it seems like different dealerships handle it differently. My dealership said for certain if they find a hole in the follower everything would be replaced.

[pezgoon]

So my tuning shop here is certain that i need a new intake cam.

We think that the PO had a blown follower (for who knows how long), replaced the follower, but damage was likely done at that point. So this got me thinking...

I called my local Audi dealership so they can verify the cam/hpfp warranty. Im still within the timeframe and only have 85K. The service writer told me that if I'm having fueling issues i can pay them to inspect the pump, and if they find a hole in the follower everything will be replaced under warranty. Problem is I replaced my follower about 8-10k ago so I doubt its warn through, but who knows. I will check it on saturday.

If I see cam damage but the follower is ok, I'm going to find a blown follower and slap it on there, drive to audi, and ask them to inspect. I will have to uninstall my tune first for sure though

If any of the previous posters have thoughts on this let me know. Ive read through the extended warranty thread and it seems like different dealerships handle it differently. My dealership said for certain if they find a hole in the follower everything would be replaced.

Everything I've read says that same thing, they will also do it for certain codes if you push them to, the trouble is having the hole or the codes!

[Low and Behold]

Hell yes!

Now, anyone have a blown follower laying around ?

[pezgoon]

Lol I know mickmerr did a few weeks ago, I changed it for him! Maybe you can try asking if he's still got it and can send it to you! Shit was blown clear through

[Low and Behold]

Sweet. Sent him a PM... Hopefully he still has it

[Low and Behold]

Updating this for the helluvit. Hoping it could help folks in the future.

1. VC changed. Oil consumption fixed
2. Uninstalled the tune in preparation to have Audi "check the cam/follower" and the car ran great.
3. Audi changed the cam/pump/follower under warranty.
4. Reinstalled the tune. Car ran better for sure, but still some hesitation and preignition. Not nearly as much as before

SO, at this point I'm going to do some logging to narrow it down a bit further. Definitely feels fueling related still. My thoughts are either PRV or one of the pressure sensors.

Will post logs when I have them

[derrek]

Updating this for the helluvit. Hoping it could help folks in the future.

1. VC changed. Oil consumption fixed
2. Uninstalled the tune in preparation to have Audi "check the cam/follower" and the car ran great.
3. I was able to use some resources and magic to get Audi to change the cam/pump/follower under warranty.
4. Reinstalled the tune. Car ran better for sure, but still some hesitation and preignition. Not nearly as much as before

SO, at this point I'm going to do some logging to narrow it down a bit further. Definitely feels fueling related still. My thoughts are either PRV or one of the pressure sensors.

Will post logs when I have them

If you're still getting oil in the IC pipes compression test and if thats bad leak down test. I've had blow by fill my catch can before, it could be sending it all threw your pcv system that reroutes back to the turbo inlet.

For fuel, log your LPFP I bet its not keeping up with whats requested and causing you to run lean.

[Low and Behold]

As stated above, the changing the VC fixed the consumption...

Will log LPFP for sure


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[Wharfbanger]

I was interested to find this thread. I have owned my 2008 2.0T Quattro for 2 months, 6MT. 93,000 miles. Went APR stage 1 a month ago. I have been getting some detonation in 4th after flooring it on steep uphill from about 1800-2000rpm. Definitely detonation, no doubt about it. At the top of the hill I pulled over and did a U-turn. The engine missed a little and belched some smoke as I pulled away in 1st. Then, it ran fine as I headed home without loading the engine or attempting to make it detonate.

Worried, I did some googling and read that carbon deposits in the cylinder can cause detonation. The theory is that carbon builds up and raises compression and this causes detonation. I am aware that the 2.0 TFSI engine is prone to carbon deposits.

One of the recommendations was an Italian tune up. Basically take it out for a spirited drive, enough to hit the red line a bit. All the heat and energy will hopefully dislodge the carbon. To cut a long story short I did the "tune up". I repeated the uphill stretch in 4th and it would appear the problem is solved - same fuel, no detonation.

I have done a couple of tune-ups now and both times it has fixed the detonation issue - for a time. Oh, the car uses a lot of oil - my last quart went in 540 miles.
So I was very interested in your comments that oil through the intake could be lowering the octane and causing detonation. This would potentially explain both issues. Does anyone have any suggestions?

[Okedokey]

What fuel you using?