Got caught driving in the middle of nowhere last night, coming home from a Christmas party, and was running out of gas. I stopped literally at a one pump gas station, and filled up with their finest 87 octane. There were tractors being repaired in their bay, because harvest time had just finished.

The rest of the night was magical. 5 miles from the station, the check engine light came on, to tell me the car was running like crap, and the restricted performance message was enough for the Mrs. to start complaining about how my British piece of crap was going to get us stranded, and possibly hacked up by zombies.(as her bare feet rested on actual sheep hides) I got this idea from Rolls Royce and Bentley, and seldom drive on trips of any length, wearing shoes. Her Cherokee would never do that, and I have actually seen it operate on goat pee.

Well, we made it home, and I plugged in the code reader only to find out that both banks were running rich. I presume this is because of the additional fuel needed to keep things ticking, but as of a few minutes ago, I was contemplating dumping $30 of octane boost in the tank, just to see if that was the problem.

I am assuming that the urine I pumped into the tank caused the knock sensors to tell the control unit to retard the timing it's full 45 degrees, and open the injectors at full duration, to stop any detonation. Anyone else have any ideas????........Thanks......Mike

 

Detonation from low octane fuel does not cause codes to be set or an RP light. If the control system runs out of authority, the engine will knock/ping. When you measured fuel trims ( in neutral, at idle or 2500 RPM) detonation is not occurring as there is no load on the engine.

My guess is the symptoms are due to something else, possibly a massive vacuum leak.

Many many owners have run their 4.0 and 4.2 engines on 87 AKI without issue.

 

. . . or some really bad gas from a one pump station.

I will assure you that it is not the 87 octane alone.

 

What were the codes you got?

 

The codes were for running too rich bank 1, and running too rich bank 2. I assume they are picked up by the upper O2 sensors.

The car idles like glass, and drives fine. The one thing I did notice is that when the ac compressor clicked on, there was an ever so slight hesitation at idle in gear. Prior to whatever happened, the ac compressor cycling wouldn't have done that.

I also wouldn't put my money down on the 87 octane being the minimum for that pump.

I will look for vacuum leaks later today, but confidence is not high. I cleared the codes, and so far the check engine light has not reappeared, but I have not put my foot in it either......Mike

 

I need the codes not what they mean all of them.

 

Gus.......Sometimes we just need to use our heads, and not a screen reading what some sensor, shoved up our car's *** can tell us. I appreciate all the help you give me, and the others, but there is a line where you need to turn away from the glowing screen, and use what the good Lord put on our shoulders. You are smart.

My reader doesn't spit out all the codes.(it only cost me $134 at Harbor Freight) It just told me, I was getting too much fuel to the top 2 oxygen sensors.(high voltage)

In the days before techs were told not to think, this message would have a number of meanings.

There was no running problem, before I filled with gas, because the mil wasn't on when I shut the car down for refueling, and the engine was running smooth as glass. Nothing negative mechanically or electrically was taking place.

After refueling, the engine popped a code or two, once it was put under load, and the new fuel had a chance to dilute what was in the lines.

The check engine light does NOT mean there is a code, in the memory. It means there are over 50 codes in the memory, and that the engine is unable to work around them, causing them to be classified as hard codes, instead of intermittent faults

Our engine control units are able to keep the engine running, by electrically advancing or retarding the ignition timing by up to 45 degrees, while also being able to adjust the duration of the injectors opening, by a hair over 15%, so as to keep the engine operating smoothly, while not damaging the catalytic converters.

In this instance, the control unit was unable to get the engine to operate in it's parameters, due to simply bad gas.

I put a bottle of octane booster(diesel fuel) into the tank, and cleared the codes. I was then able to drive almost normally, and didn't get a check engine light, until performing only the most spirited driving.

At the moment life is grand, because I drained the tank, including the valleys on either side of the sending unit, and blew out the lines. Almost $50 in gas later, and she will take any abuse I can dish out. I put 30 miles on her tonight, and will be putting another 60 miles on her tomorrow, going to a doctors appointment.

I don't know if the fuel I pumped was below grade, or had water in it, but not everything can be cured with a code. The human brain is the greatest computer of all.....Thanks everyone......Mike

 

Hey Mike--I remember the "old days" when going to my local mechanic, he could tell me what was wrong as he listened while I was driving into his shop.

By a long stretch cars these days are vastly superior, partly due to the computer engine management. But I have concluded there are also 2 downsides. The first is that the computer can adjust for little problems and mask them. But not fixing the little problem (that you are unaware of) can cascade to more serious ones. Second--decent mechanics have gone the way of the dinosaur. Nobody knows anything unless they plug in a scanner and you'd better hope the scanner correctly points to the problem. My last car (1995 Corvette) was somewhere between OBDI and OBDII and I had a slight miss that never showed up on the dealer's diagnostic scanner.

Doug

 

Sounds like excessive water to me too. Test the fuel for water content. Being the tank is full it will worsen as the tank gets lower. Pull the filter to insure. Drain the tank if a good deal of water is present.

 

Water it was. I am just glad that today's cars will do their darndest to get you where you need to go. A 73 Corvette might have left me and the Mrs. walking home, being Zombie bait.......Thanks for your ideas everyone........Mike

 

First let me say that this is not your dads Buick and reading codes does not tell you what is going on it is the interpretation of that information that puts you on the right track in today’s cars.

As for the code reader my $30.00 OBDII reader gives codes and it plugs into the OBDII plug not elsewhere.

Just remember that the O2 sensor is telling you the end results of a problem.

 

Separately, consider replacing the fuel filter. Pain to reach, but cheap and readily available. Also, there are some fuel additive out there (I presume with alcohol) that would mix with any leftover water and allow it to be picked up through the fuel system. With the cold weather presumably coming, water in the fuel system is not your friend, but you knew all of that already. Best of luck, keep us posted.

 

Ironically, the much hated E10 fuel (10% ethanol) has made frozen gas lines a thing of the past.

 

Yes, but a devil's bargain it was ...

 

Alas.....It was water in the fuel. For those of you that need to see what this phenom looks like, I will try to put up pics later. It doesn't take much to screw the pooch.

The amount of water you see at the bottom of the glass, is much more, percentage wise, than it would take to pop a code, or even stop an engine.

This is just what I wrung out of my wicking, that I had laying at the bottom of the gas tank. I just put the picture up here for those of you who never saw what gas and water look like, once they separate......Thanks....Mike

 

Glad you identified the problem. Do you plan to contact the gas station selling watered-down fuel? You may be doing many vehicle owners in your general area a big favor by putting this guy on the spot for selling crap that can ruin any vehicle it gets pumped into....

 

The station in question is about 30 miles from my house, but I did put a call in to them, telling them they have water in their underground fuel storage. The guy didn't sound like he had a whole lot of interest in this problem.

I plan on putting a call into BP today, letting them know of the situation. Another one of life's little adventures......Thank you everyone for spitballing on this one......Be cool......Mike

 

from your first post, a rural one pump station likely unchecked and or under maintain tanks which have either bad seals or cracks I would have said water in fuel. The name on the station doesnt matter, only the owners of the station and what they do to maintain their station. I have seen stations that dont have filters cartridges in those on pump filter cans so what do youthink you get in the tank? And if they even paste the gas to check for water. While E10 reduces or eliminates frozen fuel ines, it also redily ABSORBS water from the air. And another thing a vacuum leak does not give you a rich code but lean codes. The engine seesit is having to add fuel to maintain proper Air to fuel ratios and it knows this is a vacuum leak. Now to know if a vacuum leak with a reader you can monitor short term fuel trims. If it is adding more fuel at idle it is a vacuum leak(vacuum highest). If fueling is normal but is adding fuel as you increase throttle opening and rpm this is a sign of clogged/dirty injectors, fuel filter etc and not a vacuum leak as vacuum decreases with rpm and throttle opening

 

Good to see you here, Brutal. You're far too rare a sighting these days. I know you're busy but check in when you can. You are indeed missed by many of us long-time members....