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2018 Ford Mustang - Water in gas

Dealer says I have large amount of water in my gas but my car runs fine. They me a 17 oz bottle of 1/2 water and 1/2 gas and said that is what is in my tank. I always run premium gas. This diagnosis came because I have a yellow warning light staying on. Codes are P0316 and P0304. They want to drain the tank, replace plugs, and a fuel injection cleaning. I have 14,000 miles on the car. I refused the service. Is it possible for my car to run perfect if this were true?

Cant imagine that being true if it gets run regularly . This sounds like a issue with cylinder 4 , either a plug or a bad coil .

Try a different dealer, do not tell them what the first dealer said.
I would be concerned if not getting the service would void the warranty.
But the second dealership might have a better solution.

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You have codes and if you don’t have the cause fixed I think you can say goodbye to your warranty. Why you don’t seem to want to take care of an expensive vehicle is beyond me.

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vipergg that is what my FIXD tells me. Thanks for the feedback.

I definitely will Purebred, thanks for the feedback.

I agree to get a second opinion. Also, you don’t need to run premium in either the 2.3L turbo or the 5L normally aspirated engine. Regular gasoline is what Ford recommends.

Happy ending to my story. My gas does not have water as stated by the dealer. My dash light went off and my FIXD tells me there are no issues with my car. I run premium because there is a noticeable difference in the power. Thanks for your feedback. Could you send me the link to where I originally posted my issue? Thanks

the car is under warranty, get it fixed.


Does the word ( Placebo ) apply here ?

actually the owners manual says no:

Ford turbo engines typically do produce a bit more power with premium. Whether that’s worth it is up to the owner.

Water in gas these days is far more difficult then it was 20 years ago. Pretty sure all those old steel underground gas tanks have been replaced (main source for the water in gas tanks). And in many parts of the country where Oxygenated gas is required - 10% Ethanol is used with does a very good job of removing the water by letting the gas absorb it.

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[quote=“MikeInNH, post:14, topic:160743”]

Ethanol allows the ethanol/water to phase separate out of the gasoline.


Taken from link above…

Phase separation with E10 fuel

When E10 gasoline comes into contact with water, ethanol will allow fuel to absorb some or all of that water. This is actually somewhat beneficial, but fuel can reach a saturation point and water can phase separate to form a distinct layer in the bottom of the tank.

Ford HP/Torque ratings are based on 93 octane, power with 87 octane is not listed on their website. I’m sure the ECU makes adjustments according to the knock sensor and other engine parameters to get, perhaps significant, power gains with high octane fuels.

Mustang EcoBoost®Fastback Mustang EcoBoost®Convertible Mustang GT Fastback Mustang GT Convertible BULLITT Shelby GT350® Shelby®GT350R Shelby®GT500®
Engine Type 2.3L GTDI I-4 Engine 2.3L GTDI I-4 Engine 5.0L Ti-VCT V-8 Engine 5.0L Ti-VCT V-8 Engine 5.0L Ti-VCT V-8 Engine 5.2L Ti-VCT V8 Engine 5.2L Ti-VCT V8 Engine 5.2L Supercharged V-8 Engine
Displacement 2.3L (137.5 2.3L (137.5 5.0L (302 5.0L (302 5.0L (302 5.2L (315 cu.In.) 5.2L (315 cu.In.) 5.2L (315 cu.In.)
Horsepower (SAE net @ RPM) 310 @ 5,500rpm (93-octane fuel) 310 @ 5,500rpm (93-octane fuel) 460 @ 7,000rpm (93-octane fuel) 460 @ 7,000rpm (93-octane fuel) 480 @ 7,000 (93-octane fuel) 526 @ 7,500 (93-octane fuel) 527 @ 7,500 (93-octane fuel) 760 @ 7,300 (93-octane fuel)
Torque (lb.-ft. @ RPM) 350 @ 3,000rpm (93-octane fuel) 350 @ 3,000rpm (93-octane fuel) 420 @ 4,600rpm (93-octane fuel) 420 @ 4,600rpm (93-octane fuel) 420 @ 4,600rpm 429 @ 4,750 429 @ 4,750 625 @ 5,000