Too much Alchohol in my gas?


OK, a few weeks ago my 2004 Envoy began periodically hesitating and lagging if you will. It would happen under light throttle and light load, i’d notice it would be slowing on a slight hill say, and slight throttle increase would produce no change and then Ba-waa it would rev up and surge on. Sometimes it would just come back to normal. Then the “Servise Engine Soon” light came on and stayed on.

Anyway, sent it to the dealer who told me I must have gotten a bad batch of gas with “Too Much Alchohol In It”. I had never heard of this. Too much water maybe but not too much alchohol. An would it really cause this kind of problem?? Todays gas has up to 10% alchohol at least here in Mass.

Anybody heard of this??


I wonder how the “10% ethanol” will effect our cars. When manufacturing vehicles, did automakers allow for this fuel “variant” to be run in their cars? I’m not a chemist, but doesn’t alcohol burn differently than gasoline?


E10, as it’s known, contains slightly less energy per gallon than straight gasoline, and will result in slightly lower fuel economy, on the order of 4-5%.

All manufacturers of gasoline-powered cars and trucks for sale in this country engineer their cars to handle E10 without problem. Any level beyond 10% can cause problems.

To the OP: Did the dealer happen to note what the actual error code was? What was done to fix the problem?


Well I would have to check the papers and see if they are listed. They said three codes showed, one was a software issue which they installed an updated supposedly, the others they said were injector and O2 sensor related. They said they cleaned and tested both.
The car ran good for a couple days but is doing it again and the “Service Engine Soon” light is back on.


Places in the US have been using E-10 for ten years or more. No state has reported issues with “too much ethanol” in the gas. I would go back to the dealer and get the diagnosis codes from him, and then go to an independent mechanic to assess the real issue. It is obvious their diagnosis skills are lacking.

While getting “bad gas” can happen, the odds of the issue being too much ethanol is not very realistic. The station where you purchased the “bad gas” should be plagued with complaints. Since gas stations get a thousand gallons of fuel or more in a single delivery, it is hard to believe the dealer’s answer. After all, Heet treatment is also an alcohol, and we use it for gas line treatment.


The person you spoke to had no idea of the cause of thecar’s problem. Neither do we, merely from your brief description.

But we are not going to make up any baloney about bad gas or too much ethanol. You really need to have your computer scanned for the trouble codes(s). It will likely turn out to be a bad sensor somewhere.


Back to the shop for additional free diagnosis under their workmanship warranty. It is apparent the diagnosis needs to be done again, considering the duration of the “successful” diagnosis and repair. Make them try again.


Since the light is on again, take the vehicle to your local AutoZone, Advance Auto Parts, Shuck’s, etc. for a free scan of the error code(s). Post back with the actual results. The codes will be in the format of “P” followed by 4 digits, like P0123.


Agreed. The only likely place for too much ethanol in this scenario is the dealer’s lunch. Hic!


Tom McCahill, who wrote for Mechanix Illustrated magazine did not like detergent oil. He made the statement that he liked soap in his bathtub, but not in his crankcase. I bet if he were alive today he would say “I like alcohol in my martinis, but not in my gas tank”.


I’ll do that,


While I would agree with Tom McCahill on alcohol belonging in martinis, my personal experience with ethanol blends does not bear out any damage claim. I always thought his detergent claims were off-base, even when I was young and naive, in the 60’s.




Sounds like a forward O2 sensor on a four cylinder. Really similar symptom.