what fuel to prevent the EGR problem?

Here in the USA, specifically California, our gas prices are USD $3.xx/gallon right now. For our scale there are 87, 89, and 91. In other parts of the country there are places with 93. There are a very few stations around that sell a racing fuel that is 100. Unfortunately if you want to use that it is $9.xx/gallon. I found the article you shared interesting, most of the fuel sold here in California at least, is E10, whether 87, 89, or 91. Not sure what exactly is in the 100 sold around here, but I did note it is fragrance free. I guess not tainted with any sulfur.

While I'm not sure if it prevents EGR clogging, the higher the octane rating, the increase resistance to engine knock, one of the symptoms of a clogged EGR if I'm not mistaken. We have been running 91 (E10) consistently in our Prius v and have not experienced the symptoms of engine knocking but it is a low mileage car.


moto g(7) power ?

 

Your profile says that you have a 2009 Prius. In the U.S. gen 3 started with the 2010 model year. Which do you have and how many km?

 

Anecdotal and I can't say it prevented anything, however I've run top tier fuel, mostly Shell 87, octane for the 50k miles I've had the car. I just did the intake manifold and EGR cooler at 98k miles and it wasn't bad at all. Manifold, EGR pipe and cooler had some gunk but was nowhere near clogged. Valves were clean and the intake ports wiped right up with a rag. I was pretty impressed and happy to find that when I took everything apart.

 

no one knows why the egr clogs. i'm concerned about mine at only 20,000 miles. i suspect gentle driving and 2,500 miles/year make it very unhappy

 

I agree that fuel with good detergents is more important than octane. Your experience fits with my reading of forum posts. Full clogging rarely occurs before 120,000 miles and head gasket problems before 150,000. You should easily be good for another 98,000.

At the rate that you are driving, you can drive for another 11 years without problems no matter what fuel you use. So, I don't think it is worth paying for higher octane. I got my "2010" Prius in Aug 2009 and it runs perfectly on 85 octane fuel, usually Top Tier.

And at the rate you are driving, your body's plumbing will give out before your Prius does.

 

unfortunately, i'm already having problems with both

 

Techron at Chevron is a very good detergent, proven. I try to use Chevron 87 as much as I can. The 87 has Techron.

At Shell, V Power is only in the 91.

 

Some feller here watched a Chris fix video and after the video, he was completely convinced that shell provides the best gasoline. The video was also sponsored by shell.

 

Wayne Gerdes who holds a few Guinness World fuel economy records and one of the absolute experts on getting the very best fuel economy, does mileage runs for major manufactures and he swears by Shell.

 

I was surprised at how little there was. It wouldn't have clogged totally in another 50k to cause headgasket problems. I'll probably end up cleaning it every 100k when it gets plugs anyway. I'm not worried about it now for sure.

I'll add that the car gets it's neck wrung regularly. It sees large throttle openings and sustained high speeds and pretty much always gets to and stays at operating temp for hours every time it's used.

 

I'm not sure that's the advice. Higher octane gas simply resists pre-ignition better, a condition often caused by carbon build up in the combustion chamber.

EGR carbon build up is in the EGR components, possibly accelerated by PCV system providing a steady diet of additional oil to the mix, like a 2-stroke engine, lol.

And when the EGR passages are clogged, the engine runs hotter than design, due to lack of exhaust gasses, more oxygen.

My advice would be to accept that it's gonna clog, be prepared to clean it periodically, sooner than later.

 

And that’s about all we know for sure

 

It's possible Toyota got some indication that this issue is hastened by starting the car and immediately driving off, allowing moisture collected overnight to mix with the oil and pull oil through the PCV. My '14 iQ has a green coolant indicator light that stays on until sufficiently warm. I assume it means let engine warm up before pushing hard on the accelerator.

So I opened up our '12 v manual, under specifications.

It says to:

"Select octane rating 87 (Research Octane Number 91) or higher. Use of unleaded gasoline with an octane rating lower than 87 may result in engine knocking...."

It continues on the next page:

"Recommendation of the use of cleaner burning gasoline.

Cleaner burning gasoline, including reformulated gasoline that contains oxygenates such as ethanol or MTBE is available in many areas.

Toyota recommends the use of cleaner burning gasoline and appropriately blended reformulated gasoline. These types of gasoline provide excellent vehicle performance, reduce vehicle emissions and improve air quality...

Use only gasoline containing a maximum of 10% ethanol."

moto g(7) power ?

 

No, that is definately not the consensus. I've not seen any evidence suggesting higher octane fuel reduces EGR build-up.

^^^This.

 

Ethanol is cleaner burning than longer chain hydrocarbons, kind of makes sense: the goal is to go to completion/to produce CO2 (clean burn). CH3CH2OH has a proportionately higher oxygen content than a longer chain hydrocarbon. The question/concern is if ethanol is more caustic to the fuel system piping/rubber, which may be suggested by maximum limit of 10%. Our '91 Mercedes all of a sudden sprang a leak after sitting for many many years possibly damaged by oxygenated fuel that was left in the tank.....

moto g(7) power ?

 

Bad for the car in terms of damaging piping/components not ethanol tolerant is different from bad in terms of combustion process. It may be argued that ethanol has less energy density as well, and I'll accept the decreased fuel economy that comes with it, IF my engine runs cleaner, meaning burns fuel more completely to CO2. Who wants to tear down and clean their EGR if they don't have to?

It's easier to break down, aka combust

CH3CH2OH

than

CH3CH2CH2CH2CH2CH2CH2CH3 (octane, from which octane 100 is based)

to

CO2 because it ethanol has oxygen it can contribute.

My concern is the pinging, with 87 slight pinging is considered normal. I want to avoid that completely. I haven't in any driving conditions noticed any pinging...


moto g(7) power ?