So i've noticed a trend recently amongst GM's direct injection engines and it got me to thinking about my own.

The breather/PCV system in an engine is designed to direct evaporates from the engine crankcase into the engine for combustion. That's fine.. great emissions device and it keeps seals from blowing out. This oily residue has to pass by the intake valves before it gets to the combustion chamber. Sure, that's all well and good. There's only one hitch.

In a port-fuel injection engine, the fuel mixes with air in the intake manifold and passes by the intake valves to get into the cylinder. Fuel is a solvent so it tends to keep the valves very clean on top. Since direct injection engines move the fuel injectors into the combustion chamber, there's no more solvents passing over the intake valves to clean them.

I've seen more than a dozen cases of direct-injection engines with relatively low mileage (4,000 to 30,000) and long oil change intervals with gunk built up on the intake valves. This could be causing misfires as the engine is running.

That's my theory at least... Case in point, I'm buying an oil catch can as soon as I can afford to.

I think every LNF owner should.

 

Seafoam through the intake manifold every 20k miles cleans off the gunk pretty well. Catch cans will help some if you get a lot of blowby. My intake has been bone dry of oil ever since the engine break in was complete.

 

i dont got single trace of oil in my intake system and ive never cleaned it and have been modded for 2 years.

 

Meth Injection clean off gunk nicely also

 

If you get the revs high on a regular basis, it will take care of this issue. The valve rotate as they are depressed and driving a car hard will aid in reducing carbon build up. Also, as stated above, performing seafoam or a fuel service thru the throttle body will fix this as well. This is common on regular SMPI engines as well as DI.

 

or replacing your pcv system with a breather and plugging the intake hole. that's what I have currently and it has been working well.

just realized this is in the lnf section... disregard this ^^

 

it sure does.. especially a 80 - 90% mix.. i know guys who run 100% and its there daily..

 

Use sea Foam every 20k and save ur engine. I did it at 43,000 and the smoke was un-real. looked like a rocket took off.

 

I'll probably pull the intake manifold off just out of curiosity.

 

Which hose did you pour it through man cus i got people tellin me diff **** all the time

 

can you put an oil catch can on my stock airbox? I choose to do airbox mod and intake tube from ZZP

 

yes