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Poor quality gas

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Posted by: maynax

Has anyone ever had a problem with poor quality gas? I put gas in my LS last Friday and then Saturday it started shaking and rumbling horribly. Of course the dealership said to bring it on in. I figured I would check with everyone else here first. If anyone else has experienced this problem, what did you do? Did you run the tank to empty and start over? Or should I break down and take it in for diagnostics? It's a a 2000 LS Sport with about 60K on it. Am I looking at more than just bad gas, or what? I would appreciate any help with this.

Thanks,
JV

Posted by: n8bachelor

I had a tank of bad gas once. I suspected it was bad gas cause it was running rough and bad hesitation. After a day the CEL was on and the owners manual said check the gas tank cap or bad gas. The cap was on right so I put a bottle of "heat" in the tank and filled up. By the time the tank was half gone the CEL was off and it was running right. Must have been some water in the gas. Sucks bad but it does happen.

my 2¢

n8

Posted by: TheRebel

I'd try some fuel conditioner from a local auto chain. Granted I understand you don't want to keep driving it if there is a possiblity of damage. Maybe someone will chime in with better advice then mine.

Posted by: 02LSE96LSC91SE84TC

Probably the coils. Seems to be the case.

Posted by: TheRebel

Quote:

Originally Posted by n8bachelor

I had a tank of bad gas once. I suspected it was bad gas cause it was running rough and bad hesitation. After a day the CEL was on and the owners manual said check the gas tank cap or bad gas. The cap was on right so I put a bottle of "heat" in the tank and filled up. By the time the tank was half gone the CEL was off and it was running right. Must have been some water in the gas. Sucks bad but it does happen.

my 2¢

n8

sorry, didn't see that you had already replied with what I was thinking.

Posted by: Frat-man-du

This 10% ethenol crap gas attracts water. My Mark and the wife's modified Stang run like crap - I have to use drygas every other tank, just to keep the water out.

I also use at every other oil change the BG44K gas treatment. Seems to help.

Posted by: daves2000ls

i got bad gas once ran the tank to the low fuel light, went to where i usually buy gas and filled up with 93 octane and two bottles of octane booster. after that it ran fine, better than it had before i got the bad gas. come to think of it im going to do that again when i get off work.

Posted by: maynax

Thanks for the advice. I'll keep everyone posted. I'm going to run the tank to E and start over with fresh gas. Hopefully that does the trick. If not, I am probably looking at new coils, huh? Those are pricy correct?

Posted by: Frogman

I don't think you want to run the tank to "E". Water is heavier than oil (gas in this case), and will settle at the bottom. Run the tank to 1/2 maybe 1/4 full, then add more gas. That will thin out the water (if the problem is actually bad gas). and yes, get some gasoline treatment like heet, or whatever breaks up water molecules. The water won't really be removed, it will merely be "broken down" and it will more readily mix with the gas in the tank.

Posted by: maynax

I'm planning on stopping by Auto Zone and having them plug their diagnostic machine in to find out why my CEL is on. Then go get gas and do the heet thing. I'm at about 1/4 of a tank left and it seems like it's running worse as the days go on. Do coils generally just give out from one day to the next, or is it a gradual decline in performance/mpg? In the past I've consistently gotten 21-22 mpg. I really hope it is just bad gas. I'm closing on my first house at the end of September and really don't have the funds to replace all the coils if that is the problem. My wife has never been a Ford fan and said tonight that if it is more than bad gas then "we'll" never buy a Ford again. Keep your fingers crossed for me.
JV

Posted by: Cruznlife1

well the codes it's throwing (if it is bad gas) wont tell you anything....

You'll get some wild codes for EXAMPLE It may be trying to compensate, get nowhere, and throw a code for the air meter or 02 sensors, or tps, or something silly which is probably fine. Throw some fresh gas in it, the fuel is always circulating in the tank so you can add it anytime. Cheapest you can do for now. Dont bother with addatives, just fresh fuel and some driving, and see what happens, ya never know

Posted by: SoonerLS

I would bet on bad gas, not bad coils. Coils can go bad (quite often caused by oil from the leaky pre-'03 valve cover gaskets), but they normally don't just go bad as suddenly as you've described. It usually starts as a slight misfire, then gets progressively worse.

I had bad gas in my T-Bird SC once, and the symptoms were exactly like what you described. All of a sudden, it started running like crap, once or twice to the point that I actually had to pull over to the side of the road. Once I got that garbage out of my fuel system, everything was good again.

Posted by: maynax

Well, added fresh gas and a bottle of heet and the problem only slightly improved. I took it to Auto Zone and their diagnostics machine said cylinders 2,3, and 4 are misfiring and there is a bad O2 sensor somewhere in the cooling system. My question is...plugs or coils? Which ones do I replace? I would hate to do the plugs but it ends up being the coils and vice versa. Any easy way to check? What is my next step? BTW...It started running much better after I left Auto Zone. Any ideas why?