Topic: Airboy's other white car (2015 WRX...stock mufflers)

[05LGT]

That's about what I expected based on others I have seen online.  DI is great other than that one flaw.  BMWs and Audis are really bad for coking up the valves from what I have seen.

[kijho]

Kind of a silly question:  How does one go about cleaning that up? Is it something simple (someone like me with little experience could do), or can a shop generally do it for a fair price?

[dudder]

The ugly side of DI. I have been preparing myself for this reality since since the day one. Still I must admit I am also surprised by the extent of the build up.

 The plan was to install meth injection after the warranty was up, the hope was that the buildup wouldn't have been significant by that point. And therefore avoid a walnut blasting or other service. If we assume the buildup will continue at approximately the same rate (which is consistent with the early audis) I think it's pretty clear a cleaning will be in order by the time the warranty is up.

I would love to see the intake valves from a brz with the same (or greater) mileage I wonder if the port injection fires enough to keeps the valves clean.

[05LGT]

Kind of a silly question:  How does one go about cleaning that up? Is it something simple (someone like me with little experience could do), or can a shop generally do it for a fair price?

Kinda tough.  If its not terribly caked on you could run the vehicle and spray minuscule amounts of cleaner into the throttle body to allow it to pass over the valves and hopefully clean them.  We usually recommend doing a decarbonization every 32k km at GM.  If its really really bad though the only real way to solve it is to media blast them, usually with walnut shells.  This can get pretty pricey.

[10secdream]

Kind of a silly question:  How does one go about cleaning that up? Is it something simple (someone like me with little experience could do), or can a shop generally do it for a fair price?

It is a faily simple process as long as you have the proper equipment and can remove an intake manifold (really simple on the FA20).

If you want to keep peak performance then it is just another maintenance item that needs to be performed every 100,000 km (or whenever it needs to be done). Essentially you eliminate the timing belt change and replace it with intake valve cleaning.

[Tik-Tok]

I wonder if running a good quality fuel injector cleaner every few fill ups would reduce that.

[10secdream]

I wonder if running a good quality fuel injector cleaner every few fill ups would reduce that.

Negative. Fuel is injected in the cylinder and does not wash over the valves.

Methanol injection will likely reduce the build up but it won't fix the problem.

[RedndWhite]

So that's carbon build-up on the intake valves?

Would removing the EGR crap help reduce this?

[10secdream]

So that's carbon build-up on the intake valves?

Would removing the EGR crap help reduce this?

Yes that is carbon build-up.

Blocking off the EGR is suppose to help reduce it along with a proper air oil separator. Only way to tell if this works though is to inspect the build up, clean the valves, install the associated parts and review the results at a similar interval.

Unfortunately blocking off the EGR requires an accessport to remove the codes.

[RedBimmer93]

Kind of a silly question:  How does one go about cleaning that up? Is it something simple (someone like me with little experience could do), or can a shop generally do it for a fair price?

Seafoam??

[Dr Beans]

^No

That only works for the inside of a combustion chamber.

[10secdream]

From my research seafoam did not clear up the carbon build-up on Audis, BMWs and other DI motors.

Mechanics have mentioned that vehicles that have been driven "harder" than the average daily driver have less carbon build-up given similar mileage.

[05LGT]

My dad "seafoamed" his Caterham this summer and it killed the O2 sensor, and he found lightly spraying water into the intake while it was running was actually more effective than the seafoam after inspecting the cylinders with an inspection camera.

Regardless no don't bother with seafoam.

[10secdream]

There are lots of DIY's on the internet already. Some people use carb-cleaner and brushes while other people use a small walnut blaster and a vacuum pump to suck out the debris.

Either method seems to work.

[10secdream]

For reference here is a MK6 GTI motor after 16.5K miles (26,400 kms). The carbon build-up on Airboy's WRX looks worse but you get an idea of how quickly it can build-up.

http://www.golfmk6.com/forums/showthread.php?t=62797

[Dr Beans]

Are there any dyno's of before and after cleaning? I'm too lazy to look.

[Tik-Tok]

My dad "seafoamed" his Caterham this summer and it killed the O2 sensor, and he found lightly spraying water into the intake while it was running was actually more effective than the seafoam after inspecting the cylinders with an inspection camera.

Regardless no don't bother with seafoam.

People use that stuff on modern cars??? Jesus H. I would never run it through anything that isn't carb'd and catalytic converterless.

[RedndWhite]

Are there any dyno's of before and after cleaning? I'm too lazy to look.

We're harassing the correct guy's thread for that test...

[10secdream]

Are there any dyno's of before and after cleaning? I'm too lazy to look.

Likely an improvement. It needs to get bad to the point where the vehicle has a hard time idling and starts throwing codes.

[snackers]

Likely an improvement. It needs to get bad to the point where the vehicle has a hard time idling and starts throwing codes.

There is a significant drop in power before it starts throwing codes.
The BMW forums have before/after dynos.
It happens gradually, so you don't notice it. It can be upwards of 50hp. Getting it cleaned it like having a totally different car.

[10secdream]

There is a significant drop in power before it starts throwing codes.
The BMW forums have before/after dynos.
It happens gradually, so you don't notice it. It can be upwards of 50hp. Getting it cleaned it like having a totally different car.

Good to know Snackers. I am curious when you plan on tackling the intake valves on your BMW.

[Airboy]

Are there any dyno's of before and after cleaning? I'm too lazy to look.

Not a Subaru but you get the idea.

[RedBimmer93]

^^ That's pretty substantial! 

[Airboy]

That's a little dirty.

Are you seeing some issues? Or was this an investigation for curiosity's sake?

Took the pics during the installation of these:


The pictures added quite a bit of install time as I had to remove the "riser" piece between the block and the TGV.

[cha0tik]

From my research seafoam did not clear up the carbon build-up on Audis, BMWs and other DI motors.

Mechanics have mentioned that vehicles that have been driven "harder" than the average daily driver have less carbon build-up given similar mileage.

I was just gonna mention this since it's almost a requirement on diesels as well. DI motors should be run at higher RPMs so that enough heat is produced to keep the valves cleaner.

Airboy commutes a lot between Alberta and BC, a trip which would see the motor sit in the lower RPM range, which is the perfect scenario for quite a bit of carbon buildup on the valves.