Too much ethanol in engine -- does it accumulate?

This will be a bit long, but I’m providing all the information in case it sheds light on the weird things my engine is doing.

On a recent long trip, just after filling the tank at one of those highway travel plazas (Citgo, in case that matters), my aging Saturn misfired and stalled. The check engine light and the oil system lights came on, and the engine wouldn’t start again for a couple of minutes. I got it started, and it ran strangely, but it ran. Too loud, too whiny, and it didn’t like starting, but at least the car kept moving. I wasn’t too far from the dealership where I bought it, and where the mechanics still remember Saturns fondly, so I took it there. They said the main computer was dying and the mass-airflow sensor was probably dead as well. Fixed the first, which made the second check out as OK, so I went on my way.

The check engine light came on again during the trip home, so I took it to my local garage, the GM branch of a fairly large dealership. After a disturbingly long diagnosis, they told me that yes, the mass-airflow sensor was dead, but also there was too much ethanol in the engine. This is the part that confuses me. According to the mechanic, in spite of the fact that I’ve only used the gas labeled as having no ethanol locally (I live in Iowa, and pay a steep premium for skipping the subsidized corn alcohol), gas companies other than the “top tier” often put ethanol in the no-ethanol gas, and more ethanol than they’re supposed to. Also, crucially, the ethanol somehow builds up in the engine over time. He told me I had 18% ethanol in my engine and fuel system! The car is only rated for 10% at most.

I freely admit that I don’t know cars, but this doesn’t really gibe with what I remember of high school chemistry. How does the ethanol in a uniform mixture of gasoline and ethanol stay behind in the engine and fuel system, thus reaching high concentrations? The claim is that over the years I’ve lived here, the bad ethanol-rich gas has left ethanol behind, so that now, after nine or ten tanks of gas only from the “top tier” companies on this long road trip, and no refill locally yet, it still has far too much ethanol in the system.

The cure is a rather expensive one: draining the entire fuel system, flushing and cleaning it, and adding some top-tier gas back in. Then I’m supposed to buy only the highest-octane gas for a couple of tanks.

Does any of this sound reasonable? Is it just my lack of car knowledge that makes me suspicious? I would be most grateful for any advice.

Nonsense. Ethanol doesn’t accumulate. You may have gotten a tank of high-ethanol gas, but that’s it.


Ethanol is essentially unaged whisky. They actually add some gasoline at the ethanol plant in some states (including Iowa) in order not to run afoul of anti-moonshine laws. It’d be a pretty cheap bender too, because ethanol is usually around 180 proof.

So, picture what would happen if you take very high proof whisky, and spray it out of a mister onto a match. What’s left over is what’s in your engine - namely, pretty much nothing - including your eyebrows, so don’t try it :wink: .

The guy’s full of crap. Now what can happen is that if you leave ethanol-tainted gas to sit for too long, it can build up moisture in the fuel and cause running problems which are solved by draining the tank and refilling with fresh gas.

I would never use that guy again, and I’d also call the dealership owner and GM corporate and let them know they’ve got a crook working for them.

Heet is methanol (the 1-carbon alcohol); Iso-Heet is propanol (the 3-carbon alcohol); both are sold as gasoline dryers - is ethanol (the 2-carbon alcohol) the opposite? It should do the same thing.

Water separates from gas, but it gets picked up by ethanol. So any moisture that gets on the walls of the tank and which would ordinarily remain separate from the gas instead gets mixed in with the ethanol, and then that mix gets pulled out of the gasoline and given sufficient quantities the gas will degrade below its normal octane rating, which can cause the usual pre-detonation problems.

They said the main computer was dying and the mass-airflow sensor was probably dead as well. Fixed the first, which made the second check out as OK, so I went on my way.
far from home? would you return to dealer to complain?
usually changing a part will make the computer happy.
what did they fix? or replace?
they “fixed” your computer? like replaced?

Ethanol doesn’t accumulate, but it is possible that some stations spike their gas with liquids less expensive than the fuel to enhance profits… illegally.

But I suspect the mechanic was using a different type of alcohol and it was affecting his judgment. I suspect the MAF sensor was dead and he was embellishing to pad his revenue stream. I also doubt if the computer was dying. His dealership must pay their mechanics a commission for every dollar generated above a quota. He probably also attended the dealers’ seminar on “how to BS customers”.

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You can’t believe anything you hear in this context. Your mechanic might be speculating about the cause of your troubles; it’s unlikely he tested the chemical content of the fuel in tank and engine.

If it were my car, I’d take it to a fuel station where you can buy ethanol-free fuel and fill the tank. If diluting the ethanol present in the tank doesn’t abate your symptoms, I’d get a second opinion as to the diagnosis.

If you take the car to another mechanic for a second or third opinion, don’t tell them about the previous diagnoses. Let them start troubleshooting from scratch.

First, thanks for all the helpful responses!

To answer Cavell’s questions, I live pretty far from the original dealership, so can’t return. It’s the local one that is telling me the questionable story. The computer was replaced with a new one, which the former Saturn specialists said was returning no errors from other sensors. But the check engine light turned on again after just a few miles, so I suspect the mass-airflow sensor was indeed dead or dying.

I’m really concerned now about this strange story. This is the biggest dealership in the area, with branches all over South Dakota, Montana, and Iowa. It’s not Skeevy Steve’s Cut-Rate Garage, it’s an official service center for several of the larger auto manufacturers.

I guess I’ll call the service center for clarification, then contact the corporate office. Thanks for the advice!

Billion, by any chance? I always got a bad vibe off of that guy.

That wins spin-of-the-year award. ECU’s either work or they don’t work. There might be a sensor that feeds the ECU that isn’t within specs…but the main computer is dying is just plain wrong.

You may have been told that there is a high concentration of ethanol in the fuel tank, not in the engine.

If you add E85 to a non flex fuel vehicle the PCM will adjust the fuel trim in an attempt to compensate but reach its limit and set a fuel system lean fault. This condition can be misdiagnosed as a failing mass air flow sensor.

A 1989 C-10 Blazer will stall and fail to restart after about 1/4 mile on a tank of E85. But I questioned that the fuel wasn’t heavily contaminated with water. Luckily the fuel distributor didn’t choose to deny the problem and paid the tow and repair plus refunding the price of the trash I put in the tank.

MikeInNH: I probably phrased that part badly. I know the people who replaced the ECU, and trust them.

Nevada_545: Thank you! This fits all the strange parts of this story, which no other explanation had as yet. I’ll bet the Citgo station where this all started had put E85 in the wrong tank, and some of it wound up in MY tank. I’ve asked the folks at the garage if they could drain the tank (without taking the whole system apart!), put in some better gas, and see if that clears up the error.

Rod_Knox: That’s exactly what happened to me. I made it about a quarter of a mile before it misfired and stalled. Apparently a 2005 Saturn can handle E85 a little bit better than a 1989 Blazer, but it’s not happy about it.

Of course, the ethanol blended with gasoline is 199+ proof.

Yeah, but as cocktails go the flavor just doesn’t do it for me. :wink:

Anhydrous ethanol is so hungry for water that a bottle of it left open to the air will start to overflow from the water the ethanol pulled out of the air.

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Throw in a couple of olives and after the first 2 you’ll acquire a taste for it I’m sure.

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I expect you just got a bad tank of gas for some reason. Water, ethanol contamination, who knows? Perhaps they mean the effects of ethanol contamination builds up. So you could get it once, and there’s some damage done to some engine components, but not much of driver’s note happens. But get it again and the damage done be before gets worse, and then it does affect drivability. It’s true that ethanol could concentrate in water in the tank, but I’d guess if you had that much water in the engine would run poorly anyway.

Something just occurred to me. When you were at the dealership, was it the “service advisor” that told you this stuff? If so, I should probably point out that they’re often not terribly knowledgeable and often tell customers… well, let’s call them fabrications… to try to sound knowledgeable.