# Carbon Buildup & Holes in Exhaust Valves: A Cautionary Tale



## dannnno (Oct 30, 2010)

Hey all,

I've recently read up on the problems with carbon deposits in FSI engines, and wanted to share my recent experience with the results of this particular defect.

My car is completely stock. I have had none of the cold start or misfiring issues that other FSI drivers have experienced, although I was experiencing pinging in the 2000rpm range while driving up-hill/pushing the engine a bit, and was pretty sure that I was not getting my full 200hp. Just over a week ago, I was driving up an especially steep section of highway when the pinging got really bad, the CEL came on, and the engine started to shake quite badly, and was basically undrivable.

Turns out I had no compression in cylinder #2, and upon further inspection, the issue was with an exhaust valve. Not only was there a crack, but the characteristic carbon buildup all over all of the vales. My mechanic believes that the deposit on the problem valve superheated it and caused a crack.

I'm happy to have the issue fixed and also have had a chance to get the timing belt and water pump done while the head was off, but it was unbelievably expensive to do since I don't have the skills to do this myself. I'm pretty pissed off that a widely-acknowledged flaw in the design of the engine seems to have been the cause. Feels like this should be a cam-follower-style warranty extension situation, given the prevalence of the problem.

To everyone who's waffling over whether or not to get a properly done carbon clean, given my experience, I would highly recommend it. The cost of a clean pales in comparison to the cost of having the head off to replace a valve.

PS. As a last open-ended question to the rest of the FSI peeps, I was wondering if anyone else has had a similar experience to me with an actual crack in a valve due to the carbon buildup problem? I've seen tons of people who emptied what looked like a fireplace-worth of soot out of their engines, but no one post a picture of a cracked valve?

PPS. Pics or it didn't happen:


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## Elwood (Aug 10, 2001)

I've punched holes in exhaust valves on several older cars (with carbs). I believe the problem to be unrelated to carbon buildup. Sucks.


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## ordpetegti (May 20, 2004)

Wow. That is rough. What kind of mileage do you have on your GLI?


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## xtravbx (May 21, 2005)

I don't think is from carbon buildup.

This is from pinging/misfiring.. Which is actually pretty crazy because our ECU's do an EXCELLENT job to pull timing immediately upon any sign of detonation.

No matter what, this sucks. But I am not sure what it was caused by.


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## dannnno (Oct 30, 2010)

ordpetegti said:


> Wow. That is rough. What kind of mileage do you have on your GLI?


I'm at about 95,000km



xtravbx said:


> I don't think is from carbon buildup.
> 
> This is from pinging/misfiring.. Which is actually pretty crazy because our ECU's do an EXCELLENT job to pull timing immediately upon any sign of detonation.
> 
> No matter what, this sucks. But I am not sure what it was caused by.


Yea it's funny.. you can probably tell I'm not super knowledgable about this, but it seemed a little crazy that carbon could superheat steel to that point that it would disintegrate. This being said, although I did have pinging before the repair, I've driven about 200km since I got the car back (with plenty of replication of the scenarios in which it would ping before) and there is no more pinging. Also plenty of increase in power and fuel economy from the carbon clean.

Possible that the amount of carbon buildup on the valves was throwing the timing off > causing pinging > caused the crack in the valve? Is there anything else I should be checking on to prevent this from happening again, outside of carbon buildup?


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## [email protected] (Oct 23, 2008)

There is no carbon buildup, in the traditional direct injection sense, on the exhaust valves. The seats and valves on the exhaust side as well as the guides are subject to intense backpressure and exhaust gas temps on these small frame turbo systems. After building many heads, the valve guides are almost always a mandatory replacement area. If you look at some of the newer tsi platforms, they've increased the housing sizes on even the k03 units. I still feel that it is still too small. With the increasing frequency of ppl putting larger wheels into these small frame setups, you'll be seeing alot more of this. Especially with increased boost levels.

Usually goes like this.. premature guide or seat wear due to excessive heat, exhaust valve cannot seal propely, burnt exhaust valves due to combustion temps and pressures superheating of valve seat and rim..


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## filthyillness (Feb 13, 2010)

I'm no specialist on the matter but I would think that if it were damaged from being super heated that it would look a lot more like melted metal and not like something shot through it. Perhaps something entered into the engine and happen to makes its way into the #2 cylinder. On exit, from the combustion, shot through that section of the valve.


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## Elwood (Aug 10, 2001)

filthyillness said:


> I'm no specialist on the matter but I would think that if it were damaged from being super heated that it would look a lot more like melted metal and not like something shot through it. Perhaps something entered into the engine and happen to makes its way into the #2 cylinder. On exit, from the combustion, shot through that section of the valve.


No, that's a pretty average pic of a failed valve from heat. I don't know why they break that way, but they do.


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## [email protected] (Oct 23, 2008)

Yes, the 'burned' exhaust valve is more of a figurative term. The heat actually causes cracks and then eventually just breaks away, especially on hollow, filled valves.


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## lodermeier (Jan 10, 2011)

*valve*

This looks to me to be due to carbon deposit,and that area of the valve face area . Not just in this engine ,but the valveget hot and does not seal to the seat area, with leakage a '' blow torch effect '' takes place that is why it looks cut out , Years ago bmw had a carbon issue and want you to use teckron fuel additive , We try to get our cust. to add a BG product every other lof 6000mi maintance , Acouple of positive factors to consider, intake will not have a cold start sponge effect,and the proper amount /atomized fuel will create smooth idle ,and a o2 sensor that will cycle without having a incorrct bias...

loder


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## Bo Toichi (Jan 15, 2013)

I have seen 2 cars roll into my shop with this same issue. One was [email protected] 55k miles,stock tune. The other car a A4and chipped with 74k miles. I use Supertech inconle valves instead of stocks when I am doing these. There are also Ferrea valves out there,get them at IE,they are good quality for the price.


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## filthyillness (Feb 13, 2010)

So strange.

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## jhines_06gli (Feb 3, 2006)

The valve carbon buildup all cars have with the DI engine happens on the intake side. The exhaust valves do not gum up(or at least in the 60+ heads on FSI/TSI cars I've never seen a bit of buildup). It's definitely from the extreme heat buildup on these cars. As stated earlier, you take a very smell-frame turbo and spin it at 80,000+RPM and you are gonna get some EXTREME heat being built up in the small housing. Add a little detonation into that mix and get a small "hot-spot" formed on the valve face or piston......and you have some serious issues. We usually see the FSI/TSI valve fail like this and come in missing a much larger chunk. But when you say it had been chugging up hills for a little while when under load, how long had it been doing this? Chugging under load is typically an ignition misfire due to a weak coil, which will leave a small amount of unburned fuel in your combustion chamber and an cause even more issues for the engine. 

In the end, there are tons of things to take into consideration when you have a failure like this......as for the exact root cause, who knows 100% what lead up to this happening.


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## filthyillness (Feb 13, 2010)

Well if anybody on Jhines level of expertise have anything to add?

If not then there you have it!

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## jhines_06gli (Feb 3, 2006)

filthyillness said:


> Well if anybody on Jhines level of expertise have anything to add?
> 
> If not then there you have it!
> 
> Sent from my SGH-T999 using Tapatalk


Al has probably seen this more than me being in the aftermarket parts as well. We tune cars, but I only have about 6 K04 FSI/TSI cars floating around this area I work on, and no hybrid turbo cars. I had contemplated taking my K04 off and porting the housing and possibly getting a larger wheel installed, but the heat issue is what is mainly holding me back. Installing an EGT gauge would be a thing to monitor it, but if going through the time/effort and thought, why not just get a proper T3 housing and turbo setup, right?
J. Hines


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## filthyillness (Feb 13, 2010)

I understand what your saying. Your take on aftermarket intake manifolds?

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## jhines_06gli (Feb 3, 2006)

filthyillness said:


> I understand what your saying. Your take on aftermarket intake manifolds?
> 
> Sent from my SGH-T999 using Tapatalk


I'm wanting to work with a company to design one, we just have to get together and get the measurements and exact specs on what I'm looking for. Essentially it's already out there, I just want a slightly different design and look. But keep the separate holes to utilize the meth injection straight onto the valves with the spray and add internal venturi stacks. And of course would like to work in on development and testing for the perks of the discount for being the guinea pig(that's how I got my current HPFP, rail valve and follower). But I'm still not ready to make big power out of my GLI yet.....it's my "family car". My toys are my older cars as they are MUCH cheaper and lighter!

But from dealer experience, it's sad to say, but long term I'm seeing less issues out of the FSI than the TSI. When taken care of and maintained properly, the FSI is outlasting the TSI engines. I'm closing in on 200K miles and have basically only done maint. and the usual stuff that you would expect for a 2005-production BPY engine(just parts updating).
J. Hines


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## [email protected] (Oct 23, 2008)

jhines_06gli said:


> Al has probably seen this more than me being in the aftermarket parts as well. We tune cars, but I only have about 6 K04 FSI/TSI cars floating around this area I work on, and no hybrid turbo cars. I had contemplated taking my K04 off and porting the housing and possibly getting a larger wheel installed, but the heat issue is what is mainly holding me back. Installing an EGT gauge would be a thing to monitor it, but if going through the time/effort and thought, why not just get a proper T3 housing and turbo setup, right?
> J. Hines


I know you see this too, even on the oem level when you're seeing this repeatedly. I have literally 4 TSI K03's in the shop that have succumbed to actuator arm issues because of heat which the dealers only recourse is to warranty the entire unit as its somewhat integral to the turbine housing. The one piece non-adjustable IHI actuator arms are an absolute joke.

I spend a ton of time combating backpressure and EGT issues by engineering, manufacturing my own parts. Even upgrading garrett product...

Our own .72ar vbanded turbine housing that does not exist elsewhere (frees up a bit of the backpressures associated with the gt30 turbines in .63ar housings with no noticeable hit in response)









Our new 59mm inducer'ed extended tip wheel for 35r based frames which we've designed for decent response while maintaining elevating power levels up top. Less backpressure then the 30r turbines.









Cad designing wheel..









Disassembly of Garrett chra's to upgrade bearing race system for motorsports/race applications


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## jhines_06gli (Feb 3, 2006)

Yea.....I killed my first K03 due to the these issues and heat I would assume. I was pushing 24-26PSI daily through that poor lil guy for almost a solid year. Then one day it just stopped spooling past 15PSI and would only hold 12PSI to redline. I had every bolt-on available to the market at the time and a huge FMIC and full free-flowing exhaust trying to do everything I could to help it out. Still made almost 260hp/285ft/lb on the dyno on stage 2+ at those levels of boost. But I did everything trying to figure it out. Replaced wastegate with Forge unit, boost leak tested, logged and discussed with tuners.....nothing helped. I even wen to the extreme of installing a MBC inline with the N75 to try and trick it into allowing me to up the boost. But still it just would not have it. Installed another K03(perk of working at dealer) while I waited on Winter to do my K04 upgrade. New turbo and bam.......fixed issues.

I have seen the wastegates in K03 become deformed, break the rods, become loose in the housing....tons of things you would not expect to see, but we do. It's getting better on the gasoline side of things. But God help our diesel engineers and production managers!! Those things are sooo small and generate so much boost. WE see them grenade for no reason whatsoever. And usually once a car eats one, it comes back for a second....then it's good to go. Really wierd how the new common-rail diesels are.


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## [email protected] (Oct 23, 2008)

Nothing like personal experience and repeated diagnostics of these problems :thumbup:

I also see some other things that are brought on by backpressure issues. Elevated cylinder temps. This brings on a host of problems. Sometimes in the form of busted ring lands as stock spec ring gaps arent adequate enough to keep from kissing. When this happens, somethings gotta give. The war b/w steel and aluminum is an unfair one...


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## jhines_06gli (Feb 3, 2006)

Now you're stepping into VR-T territory. We split all 3 of the rear pistons on my buddy's. Still made 420whp, but drank oil and went through plugs like crazy. And it's usually rear cyl on a VR since the heat and naturally they have a slightly off A/F ratio due to the longer airflow chambers in the intake ports of the head.


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## [email protected] (Oct 23, 2008)

:thumbup::thumbup:

It is a modern miracle how they run properly at all. When you get rid of all the suppressors, you can hear the lopiness of those engines clearly. But oddly enough, it sounds great! Here is a 24vt that we are just about finishing up


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## filthyillness (Feb 13, 2010)

Finally! A thread where some good info is being passed between intelligent people about how things work. I say this because i frequent the FT f23t thread and its a damn animal barn in there but there is some good and decent info throughout the whole thing.

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## filthyillness (Feb 13, 2010)

Im gonna have to check out the PagParts website and see what going on there. Havent looked there since my VR6 build (speak of the devil).

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## Tutti57 (Jun 20, 2011)

filthyillness said:


> Finally! A thread where some good info is being passed between intelligent people about how things work. I say this because i frequent the FT f23t thread and its a damn animal barn in there but there is some good and decent info throughout the whole thing.
> 
> Sent from my SGH-T999 using Tapatalk


👍


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## xtravbx (May 21, 2005)

So what we're getting at, is I need to run direct port w/m or increase my fuel to decrease EGT's or I'm gonna blow things up w/ my hybrid turbo? =)


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## [email protected] (Oct 23, 2008)

xtravbx said:


> So what we're getting at, is I need to run direct port w/m or increase my fuel to decrease EGT's or I'm gonna blow things up w/ my hybrid turbo? =)


If you're going to anything like below...






where you are testing the limits of heat thresholds, you'll put a lot more stress on your engine than the car that is set up properly for it like above. Even the billeted 3071r experienced some elevated egt's. This motor is being transferred into an AWD platform and running our new 5935r setups in the near future with the current turbo kit. Enjoy the vid

Cooling down combustion temps will help a little but you will always battle restriction and exhaust reversion when you try to elevate engine VE's which is how you build power.


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## xtravbx (May 21, 2005)

Wow. Thank you for that video. Holy mother.

But realistically I'm running a hybrid turbo. It gets its fair share of abuse. Besides a free flowing exhaust, are you saying that the exhaust valves on the FSI are just too small as a general rule to keep up with constant heat abuse from the hybrid style turbo?

What is the solution?


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## [email protected] (Oct 23, 2008)

No, the exhaust valves arent small. The turbine, the housing, the frame of turbo is small. These 'hybrids' are really just k04 replicas that are delivered to you with cranked wastegates so they are forced to withstand some of the pressures that build up within. I see the bantering going on b/w some of these guys and dont want to get involved in any of it but the inconsistencies in boost control isnt entirely because of bad components. Its mostly attributed to using hardware outside of its intended purpose. Backpressure and EGT's are hard to combat without hardware changes. You reach a limit and thats it. Putting data acquisition tools like egt gauges, speed sensors, monitoring backpressure will show this. The above Cupra has a sizeable turbo setup on it and runs E85 and some timing. It makes well over 500whp which is slightly over its intended purpose so things have gotten a bit on the hotside. He did have a w/m mishap where it momentarily shut down during a hard pull and since he was cooling down the charge pressures and tuned with it, this happened...










It lost around 20% in compression on that cylinder. He's actually very lucky that the preigntion didnt take out the motor. He actually ran the nurburgring AFTER this took place with a worn out Wavetrac diff as well and still managed a very respectable time . This is the reason why he wants to go bigger. Its not necessarily to make more HP. Its to combat backpressure and to not stress the motor and combustion events.

My advice to you guys is to realize what you have. Keep it at its intended levels and dont be fooled into thinking that what you got is a 'bt' and you'll have a happier motor.


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## Elwood (Aug 10, 2001)

[email protected] said:


> My advice to you guys is to realize what you have. Keep it at its intended levels and dont be fooled into thinking that what you got is a 'bt' and you'll have a happier motor.


Thank you. Best bit of knowledge I've seen shared in a long time. The engine is engineered as a unit. The sum of the parts. You can't change one or two without effecting the rest.


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## filthyillness (Feb 13, 2010)

So a bigger turbo is at best an option suited to combat back pressure and heat. If i were to push for a bigger turbo, other than a k04 or reformed k04 id be better off in the long run as long as i dont abuse it in thinking with the mentality of more power but for more reliability...?

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## [email protected] (Oct 23, 2008)

Well, it depends on what you're doing. If you are falling for the advertising and thinking that you're getting a bolt on 350whp kit then, yes, you're better off with a larger turbo. As you're not going to get that without throwing the kitchen sink at it and dealing with the chance that you'll be experiencing failures associated with this. You'll see that most of the independent testing will fall well short of that. I do have experience with the 'hybrds'. If you are replacing a dying turbo and have a reasonable expectation, you will only have to worry about the possible quality deficiencies of a cloned product. But it does seem like the low rotating mass of these small wheels with very low tip height and small shafts dont put too much axial load on the bearing system as is the case on oem k03/k04 units.

And, yes, contrary to popular belief, a daily driven bt is much better for your motor. Puts less stress on combustion, exhibit lower egt's on average, less stress on the driveline down low. Push it hard and you'll run into the same problems because everything has a limit but at much higher power levels and engine efficiency is much higher. The bt world is pretty vast, however. You can go from T28 frame to watermelon frame so apples and oranges do apply here. This is not marketing, it is science...

If i was to make an education guess at what happened to the OP's valve... He was going uphill so he was generating alot of load. Very similiar to running elevated boost levels. Load energizes the turbo, spikes egt's. Monitors probably retarded timing at a certain point which probably had the manifold glowing red. You have backpressure surpassing 2:1 levels in the exhaust which spiked egt's further. The exhaust valve started burning, possibly igniting the soot that was collected around the valve. Way before tdc, the mixture probably preignited and as the exhaust valve closed, it found a weak seal on the compromised valve and further burned its way through... I can and would gather that with a larger turbo setup, this scenario doesnt happen as readily...


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## dannnno (Oct 30, 2010)

jhines_06gli said:


> The valve carbon buildup all cars have with the DI engine happens on the intake side. The exhaust valves do not gum up(or at least in the 60+ heads on FSI/TSI cars I've never seen a bit of buildup). It's definitely from the extreme heat buildup on these cars. As stated earlier, you take a very smell-frame turbo and spin it at 80,000+RPM and you are gonna get some EXTREME heat being built up in the small housing. Add a little detonation into that mix and get a small "hot-spot" formed on the valve face or piston......and you have some serious issues. We usually see the FSI/TSI valve fail like this and come in missing a much larger chunk. But when you say it had been chugging up hills for a little while when under load, how long had it been doing this? Chugging under load is typically an ignition misfire due to a weak coil, which will leave a small amount of unburned fuel in your combustion chamber and an cause even more issues for the engine.
> 
> In the end, there are tons of things to take into consideration when you have a failure like this......as for the exact root cause, who knows 100% what lead up to this happening.


Sorry for delayed reply.. I had coilpacks done by dealer about 20-25,000KMs ago

Also, had a new episode of scariness (ugh) will detail below


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## dannnno (Oct 30, 2010)

After ~1500km of relatively blissful driving, (apart from remembering the hole in my pocketbook,) had another episode the other day coming onto the highway. Gave her some gas on the on-ramp to get up to speed, was only slightly aggressive. Got 2-3 backfires, no CEL, but a HUGE plume of white smoke behind me..

Car has been slightly spluttery since, seems to do these "unsure of itself" gear changes rather than pull in low RPMs like it did right after I had the exhaust valve replaced. I can still make it pull on hills and such, but it definitely doesn't feel like it did after the repair.

I had my mech check cam follower and HPFP while he had the head off, so I can't believe either of these are giving me problems.. Do these new symptoms shed any more light on my situation? :banghead:

Thanks all.


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## [email protected] (Oct 23, 2008)

You just had that one valve replaced? In my experience, you should change them all and check for seal. Overheated exhaust valves usually dont seat properly


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## dannnno (Oct 30, 2010)

[email protected] said:


> You just had that one valve replaced? In my experience, you should change them all and check for seal. Overheated exhaust valves usually dont seat properly


Just had the one replaced.. mechanic had them all out to clean so I'd assume (HOPE) that if any were not in good enough shape to be put back in, he would've replaced those also.

Also, if there was a bad seal on one of the valves, there would be bad compression and therefore a CEL, no?


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## [email protected] (Oct 23, 2008)

If the tech checked them, lets assume they are fine but its not just the valves. The guides, seats get worn as well when components on the exhaust start to burn. There is an old trick where you can determine burnt valves. When the engine is idling, hold a paper napkin or towel over the tailpipe. If it wants to suck it in from time to time, you have burnt valves.


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## [email protected] Motorsports (Sep 24, 2013)

[email protected] said:


> If the tech checked them, lets assume they are fine but its not just the valves. The guides, seats get worn as well when components on the exhaust start to burn. There is an old trick where you can determine burnt valves. When the engine is idling, hold a paper napkin or towel over the tailpipe. If it wants to suck it in from time to time, you have burnt valves.


That's ol'school Al :thumbup::laugh:
BUT it works! This will determine if there is exhaust reversion on the intake stroke.
Exhaust is sucked back in thru the exhaust valves, creating a low pressure condition.


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## dannnno (Oct 30, 2010)

[email protected] said:


> If the tech checked them, lets assume they are fine but its not just the valves. The guides, seats get worn as well when components on the exhaust start to burn. There is an old trick where you can determine burnt valves. When the engine is idling, hold a paper napkin or towel over the tailpipe. If it wants to suck it in from time to time, you have burnt valves.


First off, thanks Al for sticking with me through this!

Kicked it old school and did the paper test. All blow no suck, thank goodness. Taking it back to mech this morning, I'll post when he gets back to me with new synopsis. Hoping for a wrong PCV install or air filter problem!


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## dannnno (Oct 30, 2010)

Follow-up: I had a blown PCV that was leaking oil back in under load. This is incredibly frustrating considering that this part was replaced less than 30,000KMs ago under a recall notice. I started a new thread, since this one has slightly deviated at this point, to ask about a possible reimbursement of these costs.

Thanks all!


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## 5ABI VT (Nov 9, 2013)

dannnno said:


> I was experiencing pinging in the* 2000rpm range* while *driving up-hill/pushing the engine a bit*


:facepalm:

Sorry couldnt help it... Is your car a 6 speed or auto? If you hear pinging you should get those rpms up asap.. no point loading the engine and letting it struggle at low rpms.. thats just asking for holes in pistons or valves. Were the pistons ok?


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