Does Toyota have carbon build up issues?

[nielshm]

I know that Volkswagen have carbon issues with their TSFI engines with direct fuel injection. Does Toyota suffer from the same thing, or is the engines designed different to prevent this? 

What can I do to keep my engine clean? Is I understand the problem, fuel additives won't make any difference, since the walves won't be flushed by the fuel. 

Does fuel powered engines have a EGR walve, since this problem is rather normal? 

[FROSTYBALLS]

EGR issues aren't confined to either VAG or Toyota.

As regards Toyota petrol engines early 1.0 IQ's were thought to have issues with the EGR valves, but a recent customer service campaign which replaced the insulator and manifold seems to have cured the issue - 

 

[smudge-1991]

What engine do you have ...

What fuel do you use ...

Where do you drive most ... town or city 

What miles are you on ...

What's the cars history like ... 

[FROSTYBALLS]

17 minutes ago, smudge-1991 said:

What engine do you have ...

What fuel do you use ...

Where do you drive most ... town or city 

What miles are you on ...

What's the cars history like ... 

Profile states 1.2T - petrol turbo

[mickburkesnr]

Please correct me if I'm wrong: The DPF issues are down to how the car is driven. If you're driving around town or short journeys, over a period of time the DPF will become clogged up with carbon deposits and cause issues. Cars that are driven for long periods of time or on motorways don't suffer from this issue as over 50mph the DPF should regenerate itself.

Diesels, while cheaper to run, are only cheaper to run if doing over 16,000 miles a year. Otherwise it's more economical to drive a petrol. As far as I know petrols don't have DPF's as it's a diesel specific thing. So if you're driving a diesel to the shop and back every day, you're going to have a bad time eventually.

[nielshm]

Many petrol engines with direct injection soffer from massiv carbon build up in the intake manifold, or on the valves.

Question is, does Toyota struggle with the same thing, or have they found a way to avoid this?

The link shows a Audi 4.2 liter V8 after just 10.000 miles.

http://www.audiclub.dk/forum/viewtopic.php?f=19&t=28766

[Gerg]

Perhaps the Atkinson cycle feature and port turbulance of the 1.2T, and the fact that the small engine will work harder, might help prevent this?  And the fact that Toyota was so late to bring out this engine, means that Toyota had plenty of time to learn from VAG's problems.

As you said, it does seem that direct injection gasoline engines are prone to this, I haven't read of any engines other than VAG TSIs  with these problems. Did the Mitsubishi 1.8 GDI  engine (fitted to the Carisma) suffer similarly? I think that was one of the earliest direct injection petrols, so there should be lots of history...

As an aside, but GDI related, the Mitsubishi was said to suffer from very bad particulate emissions, but no one was measuring petrol engine particulates then. Particulate filters for direct injection petrol engines are coming, an automotive industry emissions expert said; the atomisation of fuel is not as effective as a port injected motor and the exhaust emissions suffers for this.

Curiously, Toyota's Lexus LS460 engine (2007 - ) was both direct and port injection. Speaking to some engine calibration engineers (not at Toyota), they told me that direct injection is not optimal for all engine conditions. So is the second set of injectors for carbon reduction in the port, or just efficiency, perhaps someone knows?  So maybe it is bigger GDI engines at light loads that suffer most?

I did read about a year ago that a future 1.8/2.0 TSI VAG engine would feature a second set of (port) injectors, but I don't know if this has happened yet.  The VAG 1.4 and 1.2 engines were comprehensively redesigned a few years ago without a second set of injectors being installed.

I am not aware of any VAG 1.2TSI and 1.4TSI suffering carbon build up yet, which is promising.

HTH

[Konrad C]

I have been reading about direct injection engines and carbon build up. The crankcase ventilation is a possible cause, as well as the EGR if fitted. Turbo if fitted can let oil flow by when the seals due to age/wear and tear. Without petrol to assist cleaning the inlet side. It will need a strip down or a chemical sprayed, to try and reduce or remove the carbon.

I think some engines have injectors into the inlets, in addition to direct injection. Lexus GS450h ('05) use the 2GR-FXE which uses both port and direct injection. VW/Audi has taken up a similar setup for some of their engines. 

Toyota dropped the 2 litre direct injection engine. In a post, a fellow member claim the Valvematic engine is direct injection, when it really is port injection. My car is Valvematic, so I know that the injectors are located in the head, but outside the combustion chamber before the inlet valves. This might give the impression the engine is direct injection, when in fact it is port injection! 

This brings me to the Auris which uses the 8NR-FTS 1.2 litre turbo engine. It has couple of the ingredients for carbon build up - direct injection and PCV. 

http://toyota-club.net/files/faq/13-01-01_faq_nr-engine_eng.htm   

The PCV has an oil separator which may need to be serviced. Also the engine runs Atkinson/Miller cycle which may help minimise carbon build up. I don't think there is a EGR.

Back to the 2 litre, I would make sure the crankcase ventilation is not bringing too much oil into the inlet.   

Can I add that fuel cleaning systems, BG44 and Terraclean won't work since they work on fuel systems, which being direct injection, won't touch the inlet side.  

Edited October 25, 2016 by Konrad C
Additional info.

[Konrad C]

On 25/10/2016 at 0:30 PM, Gerg said:

Perhaps the Atkinson cycle feature and port turbulance of the 1.2T, and the fact that the small engine will work harder, might help prevent this?  And the fact that Toyota was so late to bring out this engine, means that Toyota had plenty of time to learn from VAG's problems.

As you said, it does seem that direct injection gasoline engines are prone to this, I haven't read of any engines other than VAG TSIs  with these problems. Did the Mitsubishi 1.8 GDI  engine (fitted to the Carisma) suffer similarly? I think that was one of the earliest direct injection petrols, so there should be lots of history...

As an aside, but GDI related, the Mitsubishi was said to suffer from very bad particulate emissions, but no one was measuring petrol engine particulates then. Particulate filters for direct injection petrol engines are coming, an automotive industry emissions expert said; the atomisation of fuel is not as effective as a port injected motor and the exhaust emissions suffers for this.

Curiously, Toyota's Lexus LS460 engine (2007 - ) was both direct and port injection. Speaking to some engine calibration engineers (not at Toyota), they told me that direct injection is not optimal for all engine conditions. So is the second set of injectors for carbon reduction in the port, or just efficiency, perhaps someone knows?  So maybe it is bigger GDI engines at light loads that suffer most?

I did read about a year ago that a future 1.8/2.0 TSI VAG engine would feature a second set of (port) injectors, but I don't know if this has happened yet.  The VAG 1.4 and 1.2 engines were comprehensively redesigned a few years ago without a second set of injectors being installed.

I am not aware of any VAG 1.2TSI and 1.4TSI suffering carbon build up yet, which is promising.

HTH

Regarding the Mitsubishi GDI engine, see the following link which says some of the things mentioned on posts here:-

http://www.mitsubishi-forums.com/60-carisma-forum/49028-gdi-engine.html

As I said in my earlier reply, the owner of the Mitsubishi had problems with both the PCV and EGR. He solved them by putting filters to reduce the oil and carbon getting to the inlet side.

[TomdeGuerre]

Interesting to read about Toyota’s 1.2 turbo engine. Only way to really know these engines is to go on a course and them work on them but from review of the info there it seems

(1) The engine does have an EGR valve, operated by an electrically driven stepper motor. I thought they would have achieved exhaust gas recirculation using the variable valve timing and have less trouble that way.

(2) Apparently the engine does not have direct fuel injection. The article says the injectors are in the cylinder head but placed as close as possible to the inlet valves. This would suggest fuel being port injected close to the inlet valves to keep carbon formation to a minimum.

I wonder about direct injection anyway because DI engines have greater carbon formation around injector tips and piston crowns. As previously mentioned, Toyota has modded Lexus DI engines to also have port injection.

(3) The thermostat opening temperature is given as 80 to 82 deg C. That’s a very cold temp, maybe OK in very high ambient temperatures but not very good for getting up to heat on a winter morning.

(4) The engine has a claimed 185 Nm of torque between 1,800 and 5,000 rpm and I find this hard to believe. For one thing it will not produce this power while it is in the Atkinson cycle. So far I’ve never seen any independent verification of the claimed power/TQ graphs.

 

[Konrad C]

It seems that Terraclean do have a cleaning system for direct injection engines:-

http://www.terraclean.net/product.php?id=2

Probably because of the increasingly popular use nowadays. 

[Antti]

Hi!

Does the fuel octane level affect this in some way? More gasoline and less ethanol equals more carbon?

 I just bougt a 2015 model auris touring sports with 1.2 T engine. The car has been going for 8000km so it is relatively new still. Here in Finland when it gets really cold during the winter time (-20-35 celsius is pretty common in the north) petrol car owners are used to raise the octane level for better milages and cold starts during this season. What has been confusing me is the Atkinson and turbo combination. It is a common knowledge here that turbo charged engines go better with higher octane fuel. On the other hand I've read from Prius owners that a Atkinson engine runs better with e10 fuel than with higher octane or, premium, fuels. And some even claimed that premium fuels can even be harmful for Atkinson cycle. Well here in Finland what we have on petrol stations are almost only 2 options. 95e10 or, the most popular for winter for all petrol car users, 98e5. Shell still sells v-power but the new stuff is same as the 98e5 now days.

My question is. Is it better for low temperatures for me to use which fuel in my 1.2 T Auris? And if I choose the 98 octane 5% ethanol will it damage the engine somehow due the Atkinson cycle? I know the turbo would benefit from it. 

Thanks in advance and I clad that I joined the Toyota club :)

Antti Päätalo

Finland

[Gerg]

Hi Antti,

I'm not expert on this, but, turbo engines often give better fuel economy on higher octane fuels as they are able to adjust themselves to make use of the higher 'knock' threshold that those fuels have. 

Despite his American origins, the bloke who wrote this piece below seems to know plenty when it comes to combustion chamber design. This link might be worth a read if you need to know more about engine efficiency, or you are suffering from insomnia:-  http://www.contactmagazine.com/Issue54/EngineBasics.html)

That is not to say that running on a lower octane will harm the engine; you will just achieve a slightly poorer fuel economy. The engine is just as happy on either, and as a turbo, has a 'knock' sensor (a sort of piezo microphone) attached to the engine to prevent any excessive 'knock' taking place. So on higher octane fuels the engine is said to 'run better', which really just means it gives a bit more power as the engine can take advantage of that fuel to run more turbo boost or a different ignition advance curve.

As to why it starts better on 98e5, I would imagine that with the alcohol content reduced, the fuel is a little more volatile and so more readily ignitable.

I can not see why an Atkinson cycle engine would run better on a lower octane fuel.

I'm sure someone who knows more will be along soon.