2015+ S550 GT REFUEL BOGGING/DYING

[eboybrown]

Hi guys I have a 2015 Mustang gt premium with a few bolt on mods done to the car, I got the car almost 2 years ago with 27k miles on it and have had this issue ever since, I just never really looked into it and put up with the problem but now I’ve had enough and want my car to have no problems. After refueling at a gas station (from E, I haven’t tested from any other capacity at refuel) I’ve noticed that when I start the car it struggles to run for a few seconds, idle dips down really low like it’s misfiring and struggles to stay alive, revving it doesn’t help that much and just bogs it down more. After a few seconds of that happening the idle and drive ability returns to normal. I’ve heard some stuff that it might be emissions component related so I tried replacing the purge valve by the throttle body to no avail, any other suggestions? Thank you.

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[Golgo69]

Hi guys I have a 2015 Mustang gt premium with a few bolt on mods done to the car, I got the car almost 2 years ago with 27k miles on it and have had this issue ever since, I just never really looked into it and put up with the problem but now I’ve had enough and want my car to have no problems. After refueling at a gas station (from E, I haven’t tested from any other capacity at refuel) I’ve noticed that when I start the car it struggles to run for a few seconds, idle dips down really low like it’s misfiring and struggles to stay alive, revving it doesn’t help that much and just bogs it down more. After a few seconds of that happening the idle and drive ability returns to normal. I’ve heard some stuff that it might be emissions component related so I tried replacing the purge valve by the throttle body to no avail, any other suggestions? Thank you.

Geez....where should I start....what bolt on mods have been done that you know of? Also, hook that thing up to a diagnostic reader and pull some codes. I'm sure many more people will chime

 

[ORRadtech]

I agree, we need more information. A code scan is a good start. Although sometimes evap problems don't throw codes right away. A bidirectional scan tool will go a long way to keep you from loading the parts cannon.
You said that you replaced the purge valve but that's not the only thing that can cause your symptoms. In the emissions alone there's also a vent valve and tube on the fuel tank as well as a charcoal canister. Both can cause those symptoms. Unfortunately, on the Mustang, those are insanely difficult to replace since the subframe has to be dropped in order to drop the tank.

 

[Snakebyte]

I agree, we need more information. A code scan is a good start. Although sometimes evap problems don't throw codes right away. A bidirectional scan tool will go a long way to keep you from loading the parts cannon.
You said that you replaced the purge valve but that's not the only thing that can cause your symptoms. In the emissions alone there's also a vent valve and tube on the fuel tank as well as a charcoal canister. Both can cause those symptoms. Unfortunately, on the Mustang, those are insanely difficult to replace since the subframe has to be dropped in order to drop the tank.

The charcoal canister was my first thought, but as @ORRadtech stated, there could be other sources of your symptoms.

 

[eboybrown]

Sorry forgot to mention there are no codes for anything evap related. My mods are catless longtubes with a full cat back, CAI, throttle body, tune. The CEL you’ll see in the video is related to my down stream o2 sensors because I am catless. But the car still had this issue with the stock headers and cars so I know that’s not the problem, and my tuner said they couldn’t see anything causing that issue which is why I think it’s an emissions issue.

 

[eboybrown]

Sorry forgot to mention there are no codes for anything evap related. My mods are catless longtubes with a full cat back, CAI, throttle body, tune. The CEL you’ll see in the video is related to my down stream o2 sensors because I am catless. But the car still had this issue with the stock headers and cars so I know that’s not the problem, and my tuner said they couldn’t see anything causing that issue which is why I think it’s an emissions issue.

Note that I am giving it a slight amount of gas in this video to show how it bogs down like it’s going to die. Usually it’ll do that on its own without any revs.

 

[K4fxd]

Do you over fill your tank. IE do you stop fueling when the pump shuts off or do you continue to fill till it won't take any more?

 

[eboybrown]

Do you over fill your tank. IE do you stop fueling when the pump shuts off or do you continue to fill till it won't take any more?

I always stop when it clicks, never overfill.

 

[WildHorse]

I always stop when it clicks, never overfill.

Test the ethanol content (assuming you have an E85 tune since you said "E" . Barring that, Next fill up try a different gas station.

 

[eboybrown]

Test the ethanol content (assuming you have an E85 tune since you said "E" . Barring that, Next fill up try a different gas station.

I actually meant E as in empty not ethanol, I don’t run e85 in the car only 93 octane.

 

[WildHorse]

I actually meant E as in empty not ethanol, I don’t run e85 in the car only 93 octane.

oh my bad. could be leaky injectors since you have no codes coming up.

 

[ORRadtech]

oh my bad. could be leaky injectors since you have no codes coming up.

A quick and dirty way to check that is to have someone else start the car while you stand behind it to smell the exhaust. If an injector is leaking there's a decent chance the exhaust will smell rich (unburnt fuel).
Should you smell fuel you'll want to get that fixed asap as that will damage cats, if you still have them.

 

[eboybrown]

Oil does/has not smelled like gas since I bought it. I also tried that test and it smells like normal fumes.

 

[eboybrown]

I’m going to replace my evap canister solenoid valve at the end of this week, I will update everyone if the issue persists.

 

[Cloan]

Sounds like you are getting fuel into the evap system when filling the tank. There is a check valve in your filler neck that is supposed to seal off the evap system during fueling and there's a good chance it is no longer doing that. The car will run rough for a few seconds after fueling because it's ingesting excess fuel through a system that is only supposed to be providing fumes.

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