DI intake valve deposits

[edyvw]

Originally Posted By: Mykl
I'm not sure how people on the TSI forums are able to effectively test the difference in carbon build-up resistance between holding the RPMs at 4000 for 20 minutes versus redlining the car several times a day. If those forums could outline their technique for testing and measuring the results, I could buy into it.

I never said that my car didn't have build-up. What I'm saying is that if the build-up isn't impacting the engine's operation, reliability, or durability then why should I care? My car is in your "definitely will break" envelope, so I guess we'll see what happens.

Well, my CC has 61K, no issues, avg. consumption is 28.9 (lot of city too). Driving often between C. Springs and Denver, on open road always hits 36-37mpg.
My wives Tiguan had manifold issue when it had 32K. It was serviced in VW dealership with [censored] 5W40 castrol, and older person was driving car. Based on the condition of brake pads and rotors, I think that car never saw 4000rpms, like EVER!

 

[Mykl]

Doing some more research on the subject and I found this....

http://www.google.com/patents/US6866031

Essentially, in order to fight carbon deposits you need to either keep your intake valve temperatures at below 180° C to prevent it in the first place or above 380° C to remove it once it's stuck.

It goes on to state that if you go for the high heat option with engine speeds of 3000+ RPMs it is recommended that you do this for a duration of at least 20 minutes, so I suspect that this is the document where the "4000 RPM" theory was born from.

Because I have no clue what the intake valve temperature of a 2.0 TSI being asked to cruise at low load at 4000 RPMs for 20 minutes is, I have no idea how effective that approach actually is.

Conversely, my technique of running it to redline in the first four gears every now and then might not get heat in the valves to have any effect, and even if it did it may not be long enough to really help.

It seems like the best option is to find an environment where you can run your car at high RPMs at full load for longer than a few seconds at a time. Track days come to mind, but so do isolated back-roads. Since my car has had many hours of exactly this type of exercise, I'm not terribly worried about it. If my car starts running poorly as a result of valve-carbon-deposits it likely won't happen until after 100k miles, if it happens at all.

 

[Jeffs2006EvoIX]

Originally Posted By: Mykl
Doing some more research on the subject and I found this....

http://www.google.com/patents/US6866031

Essentially, in order to fight carbon deposits you need to either keep your intake valve temperatures at below 180° C to prevent it in the first place or above 380° C to remove it once it's stuck.

It goes on to state that if you go for the high heat option with engine speeds of 3000+ RPMs it is recommended that you do this for a duration of at least 20 minutes, so I suspect that this is the document where the "4000 RPM" theory was born from.

Because I have no clue what the intake valve temperature of a 2.0 TSI being asked to cruise at low load at 4000 RPMs for 20 minutes is, I have no idea how effective that approach actually is.

Conversely, my technique of running it to redline in the first four gears every now and then might not get heat in the valves to have any effect, and even if it did it may not be long enough to really help.

It seems like the best option is to find an environment where you can run your car at high RPMs at full load for longer than a few seconds at a time. Track days come to mind, but so do isolated back-roads. Since my car has had many hours of exactly this type of exercise, I'm not terribly worried about it. If my car starts running poorly as a result of valve-carbon-deposits it likely won't happen until after 100k miles, if it happens at all.


Yes the patent does reflect a "self cleaning" affect that is obtained by keeping the vehicle over 3000 rpm for 30 min. That is in the VW patent. No arguement there.

I do 4000 rpm for 20 minutes because I am never on the hwy long enough at 3000 rpm, so I just drop a couple gears for a shorter period of time. If it works or not I will find out.

a redline fun drive even on a daily basis wont do it. The valves wont get hot enough to bake off the carbon.

It is what it is. Just a by product of a DI motor.

Jeff

 

[Jeffs2006EvoIX]

Originally Posted By: Mykl
I'm not sure how people on the TSI forums are able to effectively test the difference in carbon build-up resistance between holding the RPMs at 4000 for 20 minutes versus redlining the car several times a day. If those forums could outline their technique for testing and measuring the results, I could buy into it.

I never said that my car didn't have build-up. What I'm saying is that if the build-up isn't impacting the engine's operation, reliability, or durability then why should I care? My car is in your "definitely will break" envelope, so I guess we'll see what happens.


Your car is in no envelope of mine.

It will affect reliability one day. its just if you keep the car long enough.

The dealer charges around $400-$600 to clean the valves. Not that bad considering the price of a new car. That is for sure.

Im new to VW so this whole DI, carbon issue is new to me. I guess I should have kept my Evo.

Lesson learned for me. Time will tell.

Jeff

 

[Jeffs2006EvoIX]

Originally Posted By: edyvw
Originally Posted By: Mykl
I'm not sure how people on the TSI forums are able to effectively test the difference in carbon build-up resistance between holding the RPMs at 4000 for 20 minutes versus redlining the car several times a day. If those forums could outline their technique for testing and measuring the results, I could buy into it.

I never said that my car didn't have build-up. What I'm saying is that if the build-up isn't impacting the engine's operation, reliability, or durability then why should I care? My car is in your "definitely will break" envelope, so I guess we'll see what happens.

Well, my CC has 61K, no issues, avg. consumption is 28.9 (lot of city too). Driving often between C. Springs and Denver, on open road always hits 36-37mpg.
My wives Tiguan had manifold issue when it had 32K. It was serviced in VW dealership with [censored] 5W40 castrol, and older person was driving car. Based on the condition of brake pads and rotors, I think that car never saw 4000rpms, like EVER!


You get 37mpg in your CC??? I get nowhere near that in my GTI. The CC must be geared much much taller.

Jeff

 

[Jeffs2006EvoIX]

Conversely, my technique of running it to redline in the first four gears every now and then might not get heat in the valves to have any effect, and even if it did it may not be long enough to really help.

I cannot even think of doing this (above) redline the 1st for gears?? I would be doing like 110mph. Where I live that would land me in jail quicker than you can say "officer I was just cleaning my vavles" haha

I will stick with the higher rpm's on the hwy. True we dont know the vavle temp, but since VW designed the valves to clean themselves and they in fact say to do this in their patent to reduce the build up, we must assume it works. Or at least helps.

Jeff

 

[Clevy]

Originally Posted By: Jeffs2006EvoIX

Conversely, my technique of running it to redline in the first four gears every now and then might not get heat in the valves to have any effect, and even if it did it may not be long enough to really help.

I cannot even think of doing this (above) redline the 1st for gears?? I would be doing like 110mph. Where I live that would land me in jail quicker than you can say "officer I was just cleaning my vavles" haha

I will stick with the higher rpm's on the hwy. True we dont know the vavle temp, but since VW designed the valves to clean themselves and they in fact say to do this in their patent to reduce the build up, we must assume it works. Or at least helps.

Jeff


I think to effectively clean the valves the intake air needs sustained high velocity and operating temp.
It's like fuel dilution. It's not going to get evaporated in 1 30 minute highway run after a month of short trip commuting.
A highway such as the autobahn would be perfect for maintaining this type of running condition.

 

[edyvw]

Originally Posted By: Jeffs2006EvoIX
Originally Posted By: edyvw
Originally Posted By: Mykl
I'm not sure how people on the TSI forums are able to effectively test the difference in carbon build-up resistance between holding the RPMs at 4000 for 20 minutes versus redlining the car several times a day. If those forums could outline their technique for testing and measuring the results, I could buy into it.

I never said that my car didn't have build-up. What I'm saying is that if the build-up isn't impacting the engine's operation, reliability, or durability then why should I care? My car is in your "definitely will break" envelope, so I guess we'll see what happens.

Well, my CC has 61K, no issues, avg. consumption is 28.9 (lot of city too). Driving often between C. Springs and Denver, on open road always hits 36-37mpg.
My wives Tiguan had manifold issue when it had 32K. It was serviced in VW dealership with [censored] 5W40 castrol, and older person was driving car. Based on the condition of brake pads and rotors, I think that car never saw 4000rpms, like EVER!


You get 37mpg in your CC??? I get nowhere near that in my GTI. The CC must be geared much much taller.

Jeff


It is geared like any other DSG transmission. I drove GTI DSG did not see that it is geared differently. Take into consideration, even if it is, CC is heavier car so any higher gear ratio is diminished by weight.
My friend in Alabama had CC with stick shift, he was hitting regularly on open 37-40 (if he pushes hard, meaning a lot of engine braking).
There are several factors:
1. I use summer/performance tires, not all-season tires.
2. Tire pressure is always 2-3psi higher then what it says in the book.
3. If it is downhill, I always use manual option to brake with engine as much as possible.
4. CC, although heavier, has better aerodynamics since it is 3-volumen car, not 2-volumen like GTI.

 

[Jeffs2006EvoIX]

Originally Posted By: edyvw
Originally Posted By: Jeffs2006EvoIX
Originally Posted By: edyvw
Originally Posted By: Mykl
I'm not sure how people on the TSI forums are able to effectively test the difference in carbon build-up resistance between holding the RPMs at 4000 for 20 minutes versus redlining the car several times a day. If those forums could outline their technique for testing and measuring the results, I could buy into it.

I never said that my car didn't have build-up. What I'm saying is that if the build-up isn't impacting the engine's operation, reliability, or durability then why should I care? My car is in your "definitely will break" envelope, so I guess we'll see what happens.

Well, my CC has 61K, no issues, avg. consumption is 28.9 (lot of city too). Driving often between C. Springs and Denver, on open road always hits 36-37mpg.
My wives Tiguan had manifold issue when it had 32K. It was serviced in VW dealership with [censored] 5W40 castrol, and older person was driving car. Based on the condition of brake pads and rotors, I think that car never saw 4000rpms, like EVER!


You get 37mpg in your CC??? I get nowhere near that in my GTI. The CC must be geared much much taller.

Jeff


It is geared like any other DSG transmission. I drove GTI DSG did not see that it is geared differently. Take into consideration, even if it is, CC is heavier car so any higher gear ratio is diminished by weight.
My friend in Alabama had CC with stick shift, he was hitting regularly on open 37-40 (if he pushes hard, meaning a lot of engine braking).
There are several factors:
1. I use summer/performance tires, not all-season tires.
2. Tire pressure is always 2-3psi higher then what it says in the book.
3. If it is downhill, I always use manual option to brake with engine as much as possible.
4. CC, although heavier, has better aerodynamics since it is 3-volumen car, not 2-volumen like GTI.


The summer tires you use would adversely affect mpg not help it.

Best mpg I've hit on my GTI is 31. That is calculated not using the optimistic on board computer which I have found to be 2-3mpg off.

That is with the a/c on though. I have found that drops mpg 1-2 mpg

Jeff

 

[edyvw]

As far as I know, most summer tires have lower resistance then AS, but could be that some AS have lower then summer/performance. That being said, Pilot Super Sport that I have now on the vehicle get better mpg then Kumho AS that I got new on the car (to add, I will never understand point of having All Season tires).
I constantly have high mpg on open road (me calculating on gas pump, good ole fashion way). Last tank, HWY=70%, city+30% was 31.2mpg, calculated based on miles and gallons I put in. Take into consideration that one trip, that amounted to 325 miles was to Keystone ski resort, climbing to 11,000ft.
If I have a lot of city driving, it is in mid 20's to high 20's, but that is not very good way to determine, since I love red line from start.

 

[Quattro Pete]

Originally Posted By: Jeffs2006EvoIX
You get 37mpg in your CC??? I get nowhere near that in my GTI. The CC must be geared much much taller.

The reason for his better MPG is altitude. He's at 6,000 feet above sea level.

 

[edyvw]

Originally Posted By: Quattro Pete
Originally Posted By: Jeffs2006EvoIX
You get 37mpg in your CC??? I get nowhere near that in my GTI. The CC must be geared much much taller.

The reason for his better MPG is altitude. He's at 6,000 feet above sea level.

I was getting 34-35 in CA and AL. But true, altitude will increase mpg.

 

[supercity]

How effective would aftermarket water or water/meth injection be at keeping the valves clean?

 

[SteveSRT8]

Originally Posted By: supercity
How effective would aftermarket water or water/meth injection be at keeping the valves clean?


Introducing liquids into a dry manifold design is riskier than many here think.

 

[BMWTurboDzl]

Originally Posted By: edyvw
As far as I know, most summer tires have lower resistance then AS, but could be that some AS have lower then summer/performance. That being said, Pilot Super Sport that I have now on the vehicle get better mpg then Kumho AS that I got new on the car (to add, I will never understand point of having All Season tires).
I constantly have high mpg on open road (me calculating on gas pump, good ole fashion way). Last tank, HWY=70%, city+30% was 31.2mpg, calculated based on miles and gallons I put in. Take into consideration that one trip, that amounted to 325 miles was to Keystone ski resort, climbing to 11,000ft.
If I have a lot of city driving, it is in mid 20's to high 20's, but that is not very good way to determine, since I love red line from start.


OT I know but A/S tires work well for the Southeast US. Our winter temps can fluctuate between 30F and 55F, and we rarely get ice/snow which hangs around for more than a couple of days. Snow tires wouldn't last and Summer get too hard, slippery during those sub-40 days.

 

[Mykl]

Originally Posted By: Jeffs2006EvoIX

Conversely, my technique of running it to redline in the first four gears every now and then might not get heat in the valves to have any effect, and even if it did it may not be long enough to really help.

I cannot even think of doing this (above) redline the 1st for gears?? I would be doing like 110mph. Where I live that would land me in jail quicker than you can say "officer I was just cleaning my vavles" haha

I will stick with the higher rpm's on the hwy. True we dont know the vavle temp, but since VW designed the valves to clean themselves and they in fact say to do this in their patent to reduce the build up, we must assume it works. Or at least helps.

Jeff


I think the top of fourth gear is about 95 MPH, which on the 75 mph interstates around here isn't so much over the speed limit that a quick burst to get up to that speed from an on-ramp is likely to cause me any trouble.

Also, your technique of low load at a 20 minute sustained 4000 RPMs probably isn't having the effect you think it is. Right up front I fully admit that I have zero idea what the intake valve temps in this car are at different loads and RPMs (I'd love to see the data if anyone has it), but my guess is that it doesn't get up to the "melts carbon" temperature with just an increase in combustion frequency.

I think to have a real effect you're going to want to add more fuel and air, as in find a place where you can keep your foot in it for 20+ minutes. So basically, add track days to your maintenance schedule. If four 20-25 minute sessions flat out on a race track doesn't clean those valves, it just isn't going to happen without removing the intake manifold.

 

[edyvw]

Originally Posted By: BMWTurboDzl
Originally Posted By: edyvw
As far as I know, most summer tires have lower resistance then AS, but could be that some AS have lower then summer/performance. That being said, Pilot Super Sport that I have now on the vehicle get better mpg then Kumho AS that I got new on the car (to add, I will never understand point of having All Season tires).
I constantly have high mpg on open road (me calculating on gas pump, good ole fashion way). Last tank, HWY=70%, city+30% was 31.2mpg, calculated based on miles and gallons I put in. Take into consideration that one trip, that amounted to 325 miles was to Keystone ski resort, climbing to 11,000ft.
If I have a lot of city driving, it is in mid 20's to high 20's, but that is not very good way to determine, since I love red line from start.


OT I know but A/S tires work well for the Southeast US. Our winter temps can fluctuate between 30F and 55F, and we rarely get ice/snow which hangs around for more than a couple of days. Snow tires wouldn't last and Summer get too hard, slippery during those sub-40 days.


I lived in Alabama seven years, I know what you mean, but then during that horrible, humid summer, they cannot match performance of pure summer tire.
I had AS on Mazda, however, on CC or let's say on the car you driving, I would go with performance tire, and maybe even switch to AS during winter. However, I really like long trips, and several winters I went to Detroit, Pittsburgh and Chicago. I think only because I grew up in country with lot of snow and the fact you driving on ice, snow etc for 5 months, I was able to not have problems. IMO AS tire in any kind of ice, snow is completely useless.
Only time when AS is useful, is like you said, when temperature goes down and it is dry or just simply wet.
For example, if you go to Motor Trend or other test sites, you will see that new BMW 328 has horrible braking. Go to Auto Motor ind Sport or other German/European web site, same car is rocking in braking distance, but in Europe they are delivered with performance tires, not those Continental AS tires designed strictly for the US market (though M package 328 comes with Bridgestone RE050).

 

[SteveSRT8]

Originally Posted By: Mykl

So basically, add track days to your maintenance schedule. If four 20-25 minute sessions flat out on a race track doesn't clean those valves, it just isn't going to happen without removing the intake manifold.


I love this idea. See you at the track for some valve cleaning!

 

[Quattro Pete]

Also, what's cheaper - a day at the track or valve cleaning job? But a day at the track sounds a lot more fun.

 

[edyvw]

Originally Posted By: SteveSRT8
Originally Posted By: Mykl

So basically, add track days to your maintenance schedule. If four 20-25 minute sessions flat out on a race track doesn't clean those valves, it just isn't going to happen without removing the intake manifold.


I love this idea. See you at the track for some valve cleaning!


Or, you come to my place and try to run as fast as possible to Pikes Peak, like I do sometimes. If you do not overheat engine climbing to 14,110ft, the valves for sure will be cleaned

Then, on the way back you can test how good your brakes are and whether your brake fluid is OK!