2013 GT500 Misfire

Shhhh

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2013 GT500, 15% lower, JLT CAI, Ford Racing dual TB, Lethal O/R X, Passenger side catch can.


Just changed the oil and filter. Went to fill it up with gas and on the way back I noticed it was feeling kinda funny. I've only ran VP100(Its unleaded) in it since new. Parked the car and fast forward to today(about 2 weeks of sitting). I started it up and it was flashing a code. Pulled the reader and it showed P0308. Check the plug, it looked fine. Swapped out the Coil from #8 to #4. Retuned the car just incase and started it back up. Still feeling the same and P0300, P0307 and P0308 popped up. No smoke, no noises(Other then the random misfire), just feels a little funny sitting there at idle.

Where to start looking?

Thanks
 
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Shhhh

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UPDATE: Disconnected the battery, pulled all the plugs and put in a new set of TR6's. The idle feels even worse now. As soon as it threw a code I shut it off. P0300 is all it is showing now. Drain tank and start with fresh gas? I've never had a bad tank of gas before so I'm not sure if this even qualifies?
 

Catmonkey

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I had those codes once. Here's what I found.

Headgasket_zps46d50739.jpg


Hope that's not your issue. If you let gas sit for a while, it loses octane. Fairly fresh gas is essential to go WOT.
 

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Shhhh

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That's why I've always put 100 in it because it does sit in the garage a lot. It'll run off 93 just fine. I went and spoke to the gas station and they said they haven't had any issues with the VP100 lately but they gave me a number to call tomorrow and speak with the office about any concerns or questions I have. It just seems like really odd timing that it started acting funny literally right after I got gas. I even mentioned to my fiancé on the way home from the gas station if it felt weird to her because it did to me. She didn't think so but you know how that goes, haha.

Anyone else have any ideas on what I could test/check next?
 

Catmonkey

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A compression test will rule that out. If compression is low in 7 and 8, well it's not good news.
 

MG0h3

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Considering it started shortly after fueling up, Id look there first. If this was reg pump gas I wouldn’t be as suspicious.




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2011 gtcs

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You get VP100 out of the pump? I only run VP100 as well in my Shelby but I buy it in 5 gallon cans. But if you get it from the pump it's possible that water got in the fuel. Drain the tank and get fresh fuel, if you have time to do a compression test. But it sounds like bad gas to me. Keep us posted
 

Catmonkey

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You could have water in your gas, but if P0307 and P0308 keep coming up, run the compression test. If it starts identifying other cylinders, I'd put some additive in the tank that helps with water in your fuel. Draining would be your only other option. If you have a programmer, you could have a tuner write a tune that causes the fuel pump to run full time. Disconnect your fuel line at the fuel filter and it will drain the tank pretty quickly. As soon as you're done, load your regular tune. This is tough on the battery, but it's quick. Now disposing of 18 gallons might be a problem.
 

Shhhh

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You get VP100 out of the pump? I only run VP100 as well in my Shelby but I buy it in 5 gallon cans. But if you get it from the pump it's possible that water got in the fuel. Drain the tank and get fresh fuel, if you have time to do a compression test. But it sounds like bad gas to me. Keep us posted

Yep, Pit Stop in Peachtree City,GA sells VP100 unleaded right out of the pump(Though I may switch over the cans after this). I asked how often they get a truck in and the guy I spoke with didn't know. I know at one point probably 3 years ago I was trying to get gas and It took them about 2 weeks before the gas truck came back in. So maybe it sits in the tanks for a while?

You could have water in your gas, but if P0307 and P0308 keep coming up, run the compression test. If it starts identifying other cylinders, I'd put some additive in the tank that helps with water in your fuel. Draining would be your only other option. If you have a programmer, you could have a tuner write a tune that causes the fuel pump to run full time. Disconnect your fuel line at the fuel filter and it will drain the tank pretty quickly. As soon as you're done, load your regular tune. This is tough on the battery, but it's quick. Now disposing of 18 gallons might be a problem.


It seems like the gas may have been the issue. I left first thing this morning and grabbed some Heet. Dumped it in the tank and started it up. Ran just as bad as last night but I figured I'd try to take it around the block and see if anything changes with the tank being slushed around. It was still sputtering but it seemed to be smoothing out so I kept driving it. Ended up driving it for about 20-30 minutes (stop and go/highway/backroads) and when I got home I let it idle in the garage and it just purred. I cleared the code and that was around 9am. Went and started it up again(~11:30am) and let it idle up to operating temp. Smooth as glass.

So I guess I'll just baby it on this tank and maybe when I get to a 1/2 I'll throw in some fresh 93 and start buying the 100octane from the cans for insurance. If anything else pops ups or it throws a code again I'll keep you guys updated but fingers crossed for now. I only have ~4600 miles on it so the gas does tend to sit longer then I'd like. I'm guessing a bad tank of gas combined with moisture already being introduced into the system from sitting was the culprit?

Thanks for all the help and information!
 

2011 gtcs

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Yep, Pit Stop in Peachtree City,GA sells VP100 unleaded right out of the pump(Though I may switch over the cans after this). I asked how often they get a truck in and the guy I spoke with didn't know. I know at one point probably 3 years ago I was trying to get gas and It took them about 2 weeks before the gas truck came back in. So maybe it sits in the tanks for a while?




It seems like the gas may have been the issue. I left first thing this morning and grabbed some Heet. Dumped it in the tank and started it up. Ran just as bad as last night but I figured I'd try to take it around the block and see if anything changes with the tank being slushed around. It was still sputtering but it seemed to be smoothing out so I kept driving it. Ended up driving it for about 20-30 minutes (stop and go/highway/backroads) and when I got home I let it idle in the garage and it just purred. I cleared the code and that was around 9am. Went and started it up again(~11:30am) and let it idle up to operating temp. Smooth as glass.

So I guess I'll just baby it on this tank and maybe when I get to a 1/2 I'll throw in some fresh 93 and start buying the 100octane from the cans for insurance. If anything else pops ups or it throws a code again I'll keep you guys updated but fingers crossed for now. I only have ~4600 miles on it so the gas does tend to sit longer then I'd like. I'm guessing a bad tank of gas combined with moisture already being introduced into the system from sitting was the culprit?

Thanks for all the help and information!
Glad it wasn't anything bad, I would switch to the cans of VP100.
 

Catmonkey

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Sure beats the alternative. I'd run it as far down on empty as you can and find a new station.
 

me32

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Its hard to get good 100octane from a pump because normally it sits for along time. Normally summer months wont be so bad because more people run there hot rods and will fill up with 100 octane. But fall/winter months that gas could be sitting for months before you pump it into your car.
 

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