Carbon issues with direct injection engines

[shabby]

Teflon maybe? Valves made by t-fal...
I caught around a tablespoon of oil within a week of owning the rx catch can, my cheap ebay catch was pretty much bone dry when i took it out.

 

[TridenT]

There are special treatments you can do to engine heads. Can be time consuming to do all the prep (make sure it's a clean surface) and I'm not really sure what the benefits would be since I don't know of any off the top of my head that are meant for the intake and for this particular problem. (Although would be nice... I'd do it)

An example of an engine surface treatment would be Glyptal red enamel 1201 which supposedly helps with oil flow a bit because it creates a smoother surface. I have no idea if you could use it on the intake or if it would beneficial for creating some kind of non-stick surface. Here's an example of it being used https://www.youtube.com/watch?v=77CKFnRHA3c

 

[Geoff Finlay]

Hi Everyone, I just signed up and wanted to add a little additional information for you to chew on. FULL DISCLOSURE: I'm a retired mechanic and instructor. I began designing auto diagnostic equipment about 14 years ago. Three years ago I started to look at the GDI issue. I've come up with an answer, but I don't want to use this forum to benefit, but just to pass on valuable information. This will be the first time I pass this on to a forum like this.

While the basic design of DI engines predicts that intake valve carbon fouling will eventually occur, it can be helped along and sped up considerably. If you ever left a lawn mower with ethanol blended fuel in it over the winter, the chances of that mower starting up on a couple of pulls in the spring are pretty remote. Ethanol is agroscopic, which simply means it absorbs moisture. From the atmosphere and from inside the fuel tank (condensation). It never stops absorbing water until it reaches a saturation point. At that point, along with the water, it becomes too heavy to stay in suspension, so it sinks to the bottom of the tank, next to the fuel pickup. You can Google "phase separation" and see what it looks like.

Once that mix of ethanol and water is pumped into the engine (often after an overnight cold start), it can't burn. Some of it will be forced past the piston rings and into the crankcase. Now ethanol is aggressive and very corrosive (remember that lawn mower). As it sinks into the engine oil, it basically attacks the engine oil's additive package, causing it to "gas off". There's only one place for it to go and the oily gas lands in the intake manifold and on the intake valves. If we add a little soot (there's lots in there) to the oily film that's already there, we have a bake oven in the manifold area on low/medium heat and a great deal hotter area around the intake valves.The longer it sits there, the harder it gets.

While I've read about a million words in crazy theories, this is what's happening. It's a pretty simple process. In Canada one of the oil companies sells hi octane without any ethanol in it. If you can purchase ethanol-free fuel in your area, you'll greatly slow down the process. All the theories about better synthetic oils are valid. I'll post again next week to talk about ethanol a little more. If you don't know about it, you'll be surprised.

Geoff

 

[bruceb]

Nice to know, even though my 2016 Caddy ATS Premium 3.6L V6 normally aspirated only requires 87 octane fuel. Also a company called CRC now makes a cleaner that you spray into the throttle body, say every 10-12K miles or so, which is said to clean the back of the intake valves.
But I will try to find gas with as little ethanol in it as possible and I will also use the very best Mobil 1 Full Synthetic oil as that will also keep things nice and clean.

http://crcindustries.com/auto/intake-valve-cleaner.php

 

[Rifter]

It wouldn't help any as there isn't any way for seafoam to splash onto the intake valves.

I wonder if any of these issues will be covered under warranty, as there is literally zero preventative maintenance an owner could conceivably do to prevent this..

I always suck it directly into the intake through the brake booster vaccume line, will clean the head out great that way.

 

[CrackRabbit]

I always suck it directly into the intake through the brake booster vaccume line, will clean the head out great that way.

And give your neighborhood a smokescreen that James Bond would envy...

 

[LTC8K6]

So we just need a can of HEET or ISO-HEET once in a while if we have a DI engine, to deal with any water in the fuel?

 

[Meghan54]

So we just need a can of HEET or ISO-HEET once in a while if we have a DI engine, to deal with any water in the fuel?

I'm just curious about something. If you subscribe to what Finlay posted, most of which I don't...a lot of what he posted is grounded in fact but then moves into something else...why would you substitute one alcohol for another?

If I remember my chemistry correctly, all alcohols act the same with water. Alcohols form preferential bonds with water in the presence of water. So, what's different about how ethanol acts and isopropyl alcohol acts....isopropyl alcohol is the main/only ingredient in HEET or Iso-HEET. HEET works with an alcohol to combine with water to move it through the engine, just like ethanol works in our gas. And both alcohols, ethanol and iso., will combine with water, hold it and allow it to burn through the system, just like if it was gas. Ethanol that's adsorbed a bit of water doesn't automatically drop out of the gas...only when the ethanol gets oversaturated, which in cars just doesn't happen without some sort of failure in the fuel system.

I'd also add Finley seems to be conflating problems with open air fuel systems vs. fuel systems that could almost be seen as a closed system.

Open air fuel systems, to my mind, are the fuel systems that are vented directly to the air, such as lawn mowers, boats (it's only very recently that "closed systems" are becoming available on boats), weed eaters, snow mobiles, motorcycles, and other "small engine" devices.

A closed system, on the other hand, is what's found on cars. Sealing gas cap, no other entry of raw air to the fuel system exists. Other air enters/leaves the fuel system via a charcoal canister...never allows raw air into the system, so condensation/air humidity contamination problems are almost non-existent on cars.

 

[shabby]

Nice to know, even though my 2016 Caddy ATS Premium 3.6L V6 normally aspirated only requires 87 octane fuel. Also a company called CRC now makes a cleaner that you spray into the throttle body, say every 10-12K miles or so, which is said to clean the back of the intake valves.
But I will try to find gas with as little ethanol in it as possible and I will also use the very best Mobil 1 Full Synthetic oil as that will also keep things nice and clean.

http://crcindustries.com/auto/intake-valve-cleaner.php

That's not going to work, a proper catch can is the first step, otherwise you'll need a walnut cleaning every few years to get rid of the gunk.

 

[mindless1]

Even on an open system like a lawn mower, there are emissions limits. There's no active circulation of air to introduce more moisture into the fuel while it's sitting there in the tank, engine not running.

Finlay is copy/pasting a slightly altered, deliberated sales pitch for an intake cleaning service:
http://www.directinjectionsolution.com/repairs

Base oil vaporizes when it comes in contact with hot areas like pistons. Additive packages don't stop that, so even if ethanol were to attack an additive, it won't make much difference.

The suggestion that the (small amount) water which ethanol absorbs is a problem when it blows by pistons into the crankcase is ridiculous. Normal combustion of a gallon of gas produces almost a gallon of water. The amount ethanol would increase that is small. It'll be going into phase separation at about 0.5% E10 fuel concentration so there's your upper limit in fuel intake, while the fuel itself produces around 85% volume of water from combustion in the blow-by into the crankcase. 0.5% vs 85%, really ?

 

[bruceb]

Will have to see how the engine runs after many miles. While a catch can may be of some help, GM has denied some Camaro owners engine warranty service after the use of a catch can. Would rather not use it to avoid potential issues. You would think Cadillac would already have it, if it would really help.

 

[shabby]

Will have to see how the engine runs after many miles. While a catch can may be of some help, GM has denied some Camaro owners engine warranty service after the use of a catch can. Would rather not use it to avoid potential issues. You would think Cadillac would already have it, if it would really help.

We'll you're not supposed to go back into the dealer with it installed, funny they installed a catch can in the latest camaro and it keeps its warranty.

 

[bruceb]

Yes, I know. But it does tie in to both the PVC and the oil system. So it might be hard to remove if you need to send it in for repairs quickly. Personally I do not see it causing an issue, but you still need to check engine oil level (lot of people do not check it often enough). I hope my new 3.6L V6 will not have that issue. Time will tell and maybe by then, there will be other methods to clean it with a major disassembly.

 

[Geoff Finlay]

Nice to know, even though my 2016 Caddy ATS Premium 3.6L V6 normally aspirated only requires 87 octane fuel. Also a company called CRC now makes a cleaner that you spray into the throttle body, say every 10-12K miles or so, which is said to clean the back of the intake valves.
But I will try to find gas with as little ethanol in it as possible and I will also use the very best Mobil 1 Full Synthetic oil as that will also keep things nice and clean.

http://crcindustries.com/auto/intake-valve-cleaner.php

CRC is just one of a number of products that may or may not help prevent carbon buildup. As a strategy, it would be smarter to find a fuel stabilizer that absorbs the moisture in the tank. there are quite a few of them. This would have the net effect of keeping the ethanol in the tank with the rest of the fuel and having it burn normally. The stabilizer will disperse the water safely through the engine.

 

[LTC8K6]

It's roughly 1.25X I believe...a pound of gasoline produces about 1.25 pounds of water as a by-product of combustion.

So when you drive around and burn 20 gallons of gasoline, which weighs about 120 pounds, you have produced about 150 pounds of water.

And about 380 pounds of CO2...

This water production is one reason jet engines leave contrails behind...I believe the ratio is a little higher with kerosene based fuel.

 

[LTC8K6]

I'm just curious about something. If you subscribe to what Finlay posted, most of which I don't...a lot of what he posted is grounded in fact but then moves into something else...why would you substitute one alcohol for another?

If I remember my chemistry correctly, all alcohols act the same with water. Alcohols form preferential bonds with water in the presence of water. So, what's different about how ethanol acts and isopropyl alcohol acts....isopropyl alcohol is the main/only ingredient in HEET or Iso-HEET. HEET works with an alcohol to combine with water to move it through the engine, just like ethanol works in our gas. And both alcohols, ethanol and iso., will combine with water, hold it and allow it to burn through the system, just like if it was gas. Ethanol that's adsorbed a bit of water doesn't automatically drop out of the gas...only when the ethanol gets oversaturated, which in cars just doesn't happen without some sort of failure in the fuel system.

I'd also add Finley seems to be conflating problems with open air fuel systems vs. fuel systems that could almost be seen as a closed system.

Open air fuel systems, to my mind, are the fuel systems that are vented directly to the air, such as lawn mowers, boats (it's only very recently that "closed systems" are becoming available on boats), weed eaters, snow mobiles, motorcycles, and other "small engine" devices.

A closed system, on the other hand, is what's found on cars. Sealing gas cap, no other entry of raw air to the fuel system exists. Other air enters/leaves the fuel system via a charcoal canister...never allows raw air into the system, so condensation/air humidity contamination problems are almost non-existent on cars.

The condensation is from the air in the tank above the fuel...

But yes, I was making a point about alcohols with the HEET suggestion.

 

[Geoff Finlay]

FYI, the shelf life of gasoline without ethanol is measured in years. The shelf life of ethanol blended gasoline is anywhere from 30 to 100 days. In high humidity conditions, phase separation can and does happen as early as 30 days. The most common symptom is longer-crank, hard, cold starting especially as the ambient temperature drops. Misfiring is next. Conventional wisdom is to discard separated gas, however you can find products on the net that claim to reverse the separation. I haven't tried any of them.

 

[OverVolt]

Nissan Sentra, multi-injection FTW.

Token port injection for valve cleaning, and DI for fuel efficiency.

 

[MongGrel]

The regular application of an "italian tuneup" is never a bad thing.

It used to be a thing. Not sure it is these days.

Chuck some STP Gas Treatment/etc in the tank, take the car out on the highway or a straight country road and blow the carbon out of that thing driving it

 

[Geoff Finlay]

According to Meghan54 "no other entry of raw air to the fuel system exists" Maybe I can help a little..

There are two valves in an EVAP system - VENT & PURGE. The vent valve, vents the system to the atmosphere and on most systems is OPEN (to the atmosphere) when at rest. The valve is generally inserted before the carbon canister, however it is also connected to the fuel tank*.

The purge valve is located between the carbon canister/fuel tank and the intake manifold and is normally CLOSED at rest. The EVAP system is purged after a cold start at some point, depending on the OBD2 enabling criteria. During a purge, the open vent valve allows outside air to flow through the canister as intake manifold vacuum is applied to it and the fuel tank, when the purge valve.is opened. This allows engine vacuum to draw the adsorbed fuel from the canister and vapor from the fuel tank into the engine, along with all that outside air.

*As for that open vent valve. The natural changes in pressure/vacuum inside the fuel tank vary considerably with outside temperature changes, as well as the volume of the fuel. As it expands with warm outside temperatures, a little air (above the fuel) is exhausted (through the canister and the vent valve to atmosphere). As it contracts when the temperature falls, a little air is drawn in. There is no shortage of air in an EVAP system (including the tank).

All OBD2 systems have some way to vent the tank in the event of too low or high pressure. Some imports use a double valved fuel cap. Most North American vehicles use a version of a vent valve and almost all systems have the vent valve open to the atmosphere at rest.

Geoff Finlay

 

[LTC8K6]

Nissan Sentra, multi-injection FTW.

Token port injection for valve cleaning, and DI for fuel efficiency.

Multi-injection's valve cleaning benefit was a coincidence, not the original intent. Toyota's D4-S goes back to 2005, I think. That has direct and port injection. Wiki:

The 2GR-FSE is a 3.5L engine used in the Lexus IS, GS 350, Mark X and Crown incorporate Toyota's latest D-4S twin injection fuel system. This system combines direct injection (949cc/min injectors) with traditional port injection (298cc/min injectors). Direct injection lowers the tendency to knock (detonation) and increases performance by reducing the charge intake temperature. Traditionally, direct injection engines require an in-engine mechanism such as swirl ports or specific piston crown shapes to increase air turbulence in the engine. These are in place to help achieve a homogeneous air-fuel mixture inside the cylinder at low RPM and high load, but these mechanisms inhibit performance at higher engine speeds. In the 2GR-FSE, port injection is used considerably to achieve the correct mixture without having in-engine restrictions, meaning the engine achieves specific power near the top of all naturally aspirated production gasoline engines in the world (67 kW/L, 235 kW in the Mark X). Toyota also developed a new type of injector for this engine. The dual fan spray pattern of the direct injectors is perpendicular to the piston travel with wide dispersion in the cylinder, which aids air and fuel mixture and therefore increases power and efficiency. The port injectors not only help improve the power and efficiency but they also help improve emissions, especially in the first 20 seconds after start-up (when the catalytic converter is in its warm-up stage).

For 2015 in the Tacoma, D4-S got a specific automatic cleaning cycle regimen for the valves.

http://wardsauto.com/technology/toyota-advances-d4s-self-cleaning-feature-tacoma

 

[LTC8K6]

According to Meghan54 "no other entry of raw air to the fuel system exists" Maybe I can help a little..

There are two valves in an EVAP system - VENT & PURGE. The vent valve, vents the system to the atmosphere and on most systems is OPEN (to the atmosphere) when at rest. The valve is generally inserted before the carbon canister, however it is also connected to the fuel tank*.

The purge valve is located between the carbon canister/fuel tank and the intake manifold and is normally CLOSED at rest. The EVAP system is purged after a cold start at some point, depending on the OBD2 enabling criteria. During a purge, the open vent valve allows outside air to flow through the canister as intake manifold vacuum is applied to it and the fuel tank, when the purge valve.is opened. This allows engine vacuum to draw the adsorbed fuel from the canister and vapor from the fuel tank into the engine, along with all that outside air.

*As for that open vent valve. The natural changes in pressure/vacuum inside the fuel tank vary considerably with outside temperature changes, as well as the volume of the fuel. As it expands with warm outside temperatures, a little air (above the fuel) is exhausted (through the canister and the vent valve to atmosphere). As it contracts when the temperature falls, a little air is drawn in. There is no shortage of air in an EVAP system (including the tank).

All OBD2 systems have some way to vent the tank in the event of too low or high pressure. Some imports use a double valved fuel cap. Most North American vehicles use a version of a vent valve and almost all systems have the vent valve open to the atmosphere at rest.

Geoff Finlay

I didn't post that quote...

I made the change to the actual quoted user to avoid any further confusion -- DaTT

 

[Rifter]

I didn't post that quote...

Nope but someone did, such as...

A closed system, on the other hand, is what's found on cars. Sealing gas cap, no other entry of raw air to the fuel system exists. Other air enters/leaves the fuel system via a charcoal canister...never allows raw air into the system, so condensation/air humidity contamination problems are almost non-existent on cars.

 

[Brandyk]

Hi guys,im a bit late for this discussion but i have a 1992 Toyota 1600 16valve Narrow Angle motor.Seems it was modified from fuel injection to carb.The inlet and outlet ID size of the hoses and fittings for an oil catch can,should not.be smaller than factory ID of pcv or breather.ID of my breather is 5mm (Im using 6mm ID hose),ID of pcv valve itself is 5mm.Pcv currently goes into 8mm ID nipple into the carb spacer then intake.So if i use nipples on my catch can/s of 5mm ID,i should be safe against back pressure/pressure buildup?

 

[mindless1]

^ A catch can is not a universal benefit to all vehicles. It's for direct injection engines due to the fuel not flowing over the valves to keep them clean(er). You don't have that situation with a carb'd engine, just use carb cleaner every now and then to keep the carb clean.