# Direct injection issues.



## Aussie (Sep 16, 2012)

I found this, hope it helps.

Does direct injection cause more problems than it solves? | Driving


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## EricSmit (Dec 21, 2016)

Oh boy, here we go. @XtremeRevolution


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## jblackburn (Apr 14, 2012)

Most of it comes down to PCV system design. Some automakers (VW, BMW) have had significant issues with their early engines that required intake manifold removal & walnut shell blasting. Subaru still has issues with theirs, VW has mostly sorted it (and are going to a port and direct injection system like Toyota), and Honda has had zero issues that I'm aware of. 

GM hasn't had too many issues with intake valve buildup except on early 2.4 and 3.6 engines with relatively high mileage. Their newer motors - the 2.5, 2.0T, and newer 3.6 variants (that entire engine has been redesigned a couple times) seem to be relatively trouble free in that regard. GMs method for dealing with it is to soak the valve stems in a cleaner that will dissolve the buildup. Ford recently completed redesigned their 2.0T and 3.5TT, among which a redesigned PCV system was implemented.


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## Robby (Mar 1, 2013)

GM has a proceedure that involves using a detergent fluid that is drawn into the intake side (post throttle plate) that involves the fluid being drawn into the intake system while the engine is idleing for the purpose of cleaning the backside of the intake valves.

This is a problem that seems to occur on engines with rather high blow by gasses being vacuumed out of the crankcase through the PCV system. That and intake valves that are 'overcooled' by virtue of how the coolant is circulated around the valve seat area.

To soon to tell if the new Cruze DI engine will be affected......usually starts to show around 50k miles.

Toyota is already using a system where the car has port and DI injectors.....the engine idles on the port system and goes strictly DI above 10% throttle position. I expect that this is the future for all DI systems since there is no power loss or mileage disadvantage by adopting this method.

Probably start seeing something like this in next two or so years.

Rob


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## cedingtopn (Oct 12, 2016)

would gm be using some sort or oil/air separator like they have in the new Zl1? runs into the valve cover and separates it there


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## jblackburn (Apr 14, 2012)

cedingtopn said:


> would gm be using some sort or oil/air separator like they have in the new Zl1? runs into the valve cover and separates it there


Most PCV systems already have something like this. The 1st gen Cruze has a oil separator built into the cam cover.


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## XtremeRevolution (Jan 19, 2012)

The two biggest root causes are (in no specific order), with varying severity depending on exact engine design:

- PCV tract vapors
- Exhaust gas reversion

Using an oil with a low volatility and good oxidation stability helps reduce those deposits, but ultimately you'll need to have the valves cleaned either through walnut blasting or regular use of a purpose-built cleaning solvent. A catch can will address the first cause, but not without drawbacks. 

Last time I asked this question of the GM small cars engineer I was able to speak to at the unveiling, his response was "it's an industry-wide problem." Good deflection, I thought, to having to admit that they didn't do anything to alleviate this issue.


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## Aussie (Sep 16, 2012)

Does this issue also cause problems in a diesel, which is also direct injection?


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## Boostpatrol (Jul 30, 2013)

I guess my next question would be: if they know they screwed up with the design etc, are they on the hook to deal with this maintenance wise?


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## EricSmit (Dec 21, 2016)

Boostpatrol said:


> I guess my next question would be: if they know they screwed up with the design etc, are they on the hook to deal with this maintenance wise?
> 
> 
> Sent from AutoGuide.com Free App


hahahahahahahaha hahahahahahahahaha hahahahahaha no.


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## jsusanka (Jan 31, 2011)

http://www.amsoil.com/lit/G2543.pdf

That stuff couldn't hurt every 5 or 10 thousand miles.


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## diesel (Jun 8, 2013)

Aussie said:


> Does this issue also cause problems in a diesel, which is also direct injection?


Depends on the car. BMW, for example has a horrible track record with the 335D. My Cruze, however, is at 202K miles and I've not noticed any such issues.


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## Boostpatrol (Jul 30, 2013)

I just spoke with a friend who is a super tuner who tunes for GM. He says direct injection deposits are a total farce. Its a ploy for more services out of the customer. The older DI systems were running rich at 14:1 so you would get deposits. Direct injection now sustains 16:1 air fuels. His wife's truck has 140k on it with no issues and great mileage. His 2016 Denali runs 18:1 fuels. 


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## XtremeRevolution (Jan 19, 2012)

Boostpatrol said:


> I just spoke with a friend who is a super tuner who tunes for GM. He says direct injection deposits are a total farce. Its a ploy for more services out of the customer. The older DI systems were running rich at 14:1 so you would get deposits. Direct injection now sustains 16:1 air fuels. His wife's truck has 140k on it with no issues and great mileage. His 2016 Denali runs 18:1 fuels.
> 
> 
> Sent from AutoGuide.com Free App


BS. I've seen pictures of the valve deposits and GM is still replacing cylinder heads over it. What a crock of lies. 

Sent from my STV100-1 using Tapatalk


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## Boostpatrol (Jul 30, 2013)

What year of vehicles?


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## KENSTV123 (Sep 21, 2014)

Good info here: Consumer Reports - Direct Injection engines having reliability problem - Automotive Industry & Market Discussion - GM-Trucks.com
they blame the fuel but lack of fuel across the valve obviously is the real cause, somewhere saw a bulletin of major engine repair because of the carbon buildup and IMO the raw fuel is rinsing that essential residual oil film at the top of the cylinder which equates to a long life for the engine, anybody that has torn enough engines down knows that all the cylinder wear is in the top 1/4" of cylinder, the gas spraying directly in there likely cuts all the oil film, I'm sure the engineers have thought of this and hardened the cylinders and valve seats and stems but I question the actual longevity of the direct inject engines compared to the normal fuel rail charged engines


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## XtremeRevolution (Jan 19, 2012)

Boostpatrol said:


> What year of vehicles?
> 
> 
> Sent from AutoGuide.com Free App


Clear into late model 3.6 V6s only a few years old. 

Anyone can claim brand new models are better solely due to lack of mileage. 

Sent from my STV100-1 using Tapatalk


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## jblackburn (Apr 14, 2012)

XtremeRevolution said:


> BS. I've seen pictures of the valve deposits and GM is still replacing cylinder heads over it. What a crock of lies.
> 
> Sent from my STV100-1 using Tapatalk


To my knowledge, GM does not replace cylinder heads for valve buildup on the 2.4, 3.0, 3.6 engines. They simply clean the valves.


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## XtremeRevolution (Jan 19, 2012)

jblackburn said:


> To my knowledge, GM does not replace cylinder heads for valve buildup on the 2.4, 3.0, 3.6 engines. They simply clean the valves.


They do when it gets bad enough that the valves no longer seal correctly...

Sent from my STV100-1 using Tapatalk


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## [email protected] (Nov 12, 2011)

Get a tune and run meth injection. Problem solved


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## EricSmit (Dec 21, 2016)

[email protected] said:


> Get a tune and run meth injection. Problem solved


Consider it done.


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## oreo382 (Sep 17, 2014)

Aussie said:


> Does this issue also cause problems in a diesel, which is also direct injection?


Yes it does.As I type this my 2014 diesel is in the shop having the head removed and cleaned due to intake valve deposits.Symptoms were stumbling/misfiring on first morning start,especially when put in gear,fuel mileage getting worse.Stumbling goes away when engine warms up.


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## Aussie (Sep 16, 2012)

oreo382 said:


> Yes it does.As I type this my 2014 diesel is in the shop having the head removed and cleaned due to intake valve deposits.Symptoms were stumbling/misfiring on first morning start,especially when put in gear,fuel mileage getting worse.Stumbling goes away when engine warms up.


In Australia the diesel is 50 cetane, would that make any difference?


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## jblackburn (Apr 14, 2012)

Aussie said:


> In Australia the diesel is 50 cetane, would that make any difference?


Fuel never touches the valves - it's injected into the cylinder itself directly.

Most of the crud comes from the EGR and crankcase ventilation system.


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