Soofisahab

iTrader: (2)

All,

In port injection setups, the injectors spray onto the valves which helps keep them clean of PCV garbage that gets cycled back into the intake; in a direct injection setup, the fuel is injected after the valves, therefore no cleaning. I'm thinking our intake manifolds and valves are getting throughly shitted up over time (as exhibited in a previous post on Porsche and Audi DI engines).

I ran some seafoam through my car (20000 miles) and all sorts of crap came out (made evident by the huge plume of smoke); in contrast, the smoke cloud that came off my friend's Navigator (5.7L, 70000 miles and port injection) couldn't compare.

I also have begun running some distilled water through the car every once in a while; keep the car at 2000-2500 rpm and trickly water into a vaccum port on the intake manifold to steam clean the engine (BE EXTREMELY FREAKIN CAREFUL IF YOU DO THIS, TOO MUCH WATER AND YOU WILL HYDROLOCK).

If you are removing your intake manifold, please take a picture (or comment)....I hope you disprove my theory on DI.

Oh, a catch can will do wonders for this. The breather line on the intake has a check valve so no worries. Gonna get a air compressor water separator from hardware store and put on other pcv line...anyone have diagram of pcv system?

peachpuff

No need to think, grab a scope and take a peek inside the manifold. I did and all is well, nothing on the valves.
Porsche/audi/vw have their problems, we don't.

northvibe

iTrader: (1)

yeah this seems a little over board. Honestly you would of heard the sky/solstice people complaining a while ago. On my ms3 forums everyone just ran oil catch cans and were happy.

Soofisahab

iTrader: (2)

Please specify your mileage. How hard do you drive your car? Do you have a catch can? Do you run any cleaning products through your car? Water injection?

We have blowby, right? It gets sucked into the intake via the PCV system, no fuel to wash port and valves...forgive me if I'm assuming ****

Razor564

Click

Stamina

Repost.

A GM Engineer on here already addressed this. It's not a problem on our engines.

Soofisahab

iTrader: (2)

Ok, please show me the link...need to read the logic to quiet down

Stamina

I'm still looking. Was going to post it up. It came up about a week and a half ago.

Edit: Alright, search is giving me issues. Anybody else know where it is? The guy even posted a picture of the clogged up valves on the inside of Porsche engine if anybody remembers that thread.

Edit x2: Here's one of the pics they posted up originally (found it). It's the inside of a Porsche engine with DI.. in this case a 2008 Cayenne...

We were then told by the engineer that they took apart the LNF to look for wear many times during testing, but had never seen any kind of deposits even remotely like the picture.

I think the original thread got deleted. A ton of searching on my part came up with nothing. I'll check my browser history on the computer I was using to confirm if it's around still and if so, post up the thread link.

rukkee

iTrader: (3)

When my car was new it had a terrible hesitation between 2500 and 4500 rpm . The car would just stop pulling and fall flat.....the exhaust note would change when these "bog's" would occur as well . I ran some injector cleaner threw the intake manifold because i had read a post about sticky valves when new .....they have such tight tolerances from the factory , and being dry due to DI doesn't help. After that ,not a single bog or hesitation..... It's been a different car ever since then .

buellfooll

I think I'd be careful what aftermarket additives I put in my DI LNF. What with the stainless intakes and sodium filled exhausts and all. These are high tech, high performance pieces and I'd want to know exactly how they'd react to additives. JMHO!

coffeeslug

OP, did you ever actually have a problem with your engine, or are you just the most paranoid human on Earth? You are going to screw it up big time, if you haven't already, with your "cleaning".

Soofisahab

iTrader: (2)

They watching me, son!!! Yes, I'm paranoid, neurotic, impulsive, etc...but, it is these characterisitics that serve as catalyst for my yearning to know. I bought my car 1.5 mos. ago used, just making love to it, getting in it's guts, raw.

Deposits rob performance (via intake crud), and create hot spots conducive to detonation (but that's in the combustion chamber) = simple facts. If we accumulate excessive amounts of carbon our cars are slower. After performing these simple cleanings, there is not the slightest amount of hesitiation!

Just school me, that's all I ask! Tell me how my logic is flawed, show me diagrams of the PCV system, etc....

Would you rather have the ninetyeth billion ^2 thread on the release date of the GM kit?

buellfooll

Calling all GM engineers!!! What happens when you cool something hot too rapidly? The exhaust valves must be getting hot in the LNF if they went to the expense of sodium filled valves, or they just wanted to help cool them in a controlled sort of way. I think doing what you're doing , with the water trick, is, in the long run, going to do more damage than good. Your warranty covers even carboned up valves. I don't think it will cover split open valves caused by rapid cooling. When I was a kid (a long time ago) we used to pour water through the carb for the same reason you are. With age I learned it doesn't help a bit. But in the case of the LNF it may hurt a lot.

Again. JMHO!

Area47

the gm engineer you got that info from is a crack pot.

buellfooll

That didn't come from an engineer. That's why I ended it with JMHO! But if pouring water, or any other snake oil, into your engine pour-on.

No time off MY warranty.

Area47

it was in reference to someone else. not you.

Terminator2

Dont waste your time on that catch can I did that to mine and drove it hard for few days and no oil or gunk at all in the can. GM has the valve cover pretty well baffled and that oil would be in you CPs and IC first. Pull your hotside CP near the IC there should be no oil in there mine was perfectly dry after 8k miles

007G5GT

I talked to the shop foreman (who's a fairly knowledgeable guy as far as foremans go) at my dealership about this same issue actually. I was wondering the same thing as the OP, would the PCV gunk and oil returned back into the intake stream make it's way to the valves to dirty them up. The foreman said the same thing about the head and valve cover as Term, that GM baffled it specifically for this DI setup so that if any oil did make it's way that direction that it would be caught before it hit the valves.

Maybe one of the reasons our heads flow like **** compared to the LSJ heads. Also maybe part of the reason ZZP saw such a huge increase from porting the head...wonder how much of an issue, if any, they'll have with valve gunk build-up.

Terminator2

The valve cover is well baffled enough that it think it will be a non issue. Almost no oil even makes it into the intake itself. There is a one way check valve as well to help stop anything that does get by.

rukkee

iTrader: (3)

The valves in the LNF are ....TOO dry.... if anything . There was a PI from GM about them sticking when new.

peachpuff

Around 25k miles, i drive the car the way gm meant for it to be driven.
I just installed a catch can actually, got tired of seeing oil in my intake. And i don't run anything through the motor.

Few days? Put it in for a month next time. While the lnf doesn't spew out oil like the turbocharged cars from the 90's it will still soak your intake.
This is on a 2 month old car, the green stuff is dye in the oil.

Soofisahab

iTrader: (2)

Thanks for the additional info.

Which line did you install the catch can on? How much oil are you catching over a month?Please take a pic of your installation, if you will.

peachpuff

Pics are here https://www.cobaltss.net/forums/show...7&postcount=12
I'll take a peek inside the can over the weekend.

Bandit1

I asked about this awhile back.At 4k miles,i brought the car in for an oil change(heh,felt lazy and the rpice was right),and had them check the turbo for blowby as well.I was there,and it was perfectly dry.I asked the technician why some might have it and some don't.He said probably from folks dropping the clutch too quick.Don't flame me i am just the messenger of what took place.

That aside,someone mentioning sticky valves and the effect of that,i believe i still have that issue but whatever it is,it is annoying as hell.

A catch can? would still consider it if i saw a nice writeup on the details.

buellfooll

You'll get no flames from me.

Years ago, when my 67 Firebird 400 was brand new, I made a Bonsai trip to Miami on I-95in the middle of the night. The car was brand new so naturally I had to see just how fast it would really go. I was too busy watching the road so I never did see how fast I was going till I let go the throttle and checked my mirror to see if there were any flashing lights behind me. All I saw was a plume of smoke behind the car that scared the **** out of me. The car didn't seem to be hurt so I continued my trip. As soon as I got back home in Cocoa, FL I went to the speed shop I dealt with and asked why the smoke. The owner of the place was a very knowlegable and wise long time racer and I believed whatever he told me. He said what I saw was OIL smoke that had been drawn past the not fully broken in valve guides into the combustion chamber after a sustained full throttle run (minimum manifold vacuum) where oil was collecting around the valve stem and guide, followed by a fully closed throttle (maximum manifold vacuum) where that oil was drawn past the stem and guide into the combustion chamber. This can also happen with WORN OUT guides. Wanna bet something like this is happening to the LNF? If you drop the clutch on an engine at full boost (ZERO vacuum) and then the manifold vacuum immediately, but momentarilly, pegs it would be very close to what happened to my Firebird. It may be for this reason the owners manual recommends to avoid downshifting to brake during the break in period.

Your technician probably hit the nail on the head. But of course this is only my opinion and experience talking.