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I have heard about ford direct injection engines having issues with deposit build up within the engine especially the valves and pistons.

I spoke with a friend who mentioned the issues faced by these engines due to the injector no longer being in the intake runner. He also mentioned a company who has a way to clean the deposits away but it seems costly.

Anyone heard of this? Or know of what the likes of GM have to say about this?


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

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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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Discussion Starter #14
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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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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BS. I've seen pictures of the valve deposits and GM is still replacing cylinder heads over it. What a crock of lies.

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

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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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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...

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