car seems to misfire on full load (55% and up throttle)

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so out of nowhere today after i had put about 20 bucks worth of gas (~7.5 gallons) into my car at an arco (i usually go to safeway or chevron) and the car almost immediately started having misfire symptoms. it drives fine until you decide to give it more throttle, roughly after half throttle, and then it has slight misfire, back pressure issues. also it should be worth noting that it happens at a more "severe" rate with the a/c ON. no check engine and im driving like i normally do, so its kind of throwing me off. i put in about a quarter tank (3.5), in addition, at a chevron and it feels a bit better, but still seems to have the issue. i wonder if the gas at that arco was really that bad.

ive checked the oil cap to see if it looks milky as well as checking near the spark plugs for any liquid since i did have a cracked intake issue about a year ago (this is not the same broken intake. it was replaced over a year ago with a basically brand new intake so calm your tits gents). i also looked under the car to see if there was any exhaust leaks. the last thing i need is the car to blow up (getting a lil dramatic there huh?) since i use it as a dd.

*yes [MENTION=19482]B.mad[/MENTION] i dd a racecar in training*
 

B.mad

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I DD mine too. lol. Arco sucks....
 

ttocs

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Arco was in phoenix and I quit using them myself after having issues. Another thing to avoid is do NOT get gas if the tanker truck is there fueling as it stirs up any crap that has made it into the tank and put it in yours. Also not sure about CA but I am willing to bet its the same as AZ. I can't remember what the difference is exactly now but they would switch to a cleaner burning gas for the summer that never did run as well.
 

B.mad

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Arco was in phoenix and I quit using them myself after having issues. Another thing to avoid is do NOT get gas if the tanker truck is there fueling as it stirs up any crap that has made it into the tank and put it in yours. Also not sure about CA but I am willing to bet its the same as AZ. I can't remember what the difference is exactly now but they would switch to a cleaner burning gas for the summer that never did run as well.

I refill at Costco, and never had an issue when the tanker was there. But i heard of that before.
 
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Honestly guys I'm not too sure. Could the gas really have been THAT bad to cause the fuel to be crap/misfire? I almost ALWAYS get chevron so it kinda makes sense it could be the gas, but holy crap if that's actually what's wrong then damn...
 
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Just put in about half a tank of 91 to try and clean out the possible gunk from Arco and although it does sound fvckin legit, the car is still missing. I have no idea what could be wrong but I did notice the other day that one of the spark plug wires wasnt fully on the plug so that helped a bit but it's still annoying me that I can't just floor it when I want to pass someone. Any ideas guys? I know the engine probably will need a rebuild or I may have to do the Teksid build sooner than I thought
 

1bad95

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If you suspect bad gas I'd drop the tank and drain it and put in fresh good fuel and a new filter. At least you'd will know your good on that end. Maybe throw a new set of plugs in it also and see if it clears up.

Sent from my XT1585 using Tapatalk
 

Rob04Mach1

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Misfire under load would have me checking plugs immediately but to answer your question yes the gas could be that bad and give you issues very quickly. Never heard of Arco and we dont have any I know of in NY but I have gotten bad gas in an old Lightning of mine. I was on the way to the track and the truck was running flawless, I stopped at a top brand gas station I was using for years and put some 93 in. Minutes after that I immediately felt and knew something was wrong. Like an idiot I still tried to make passes and I ended up toasting a few plugs.
I went home, swapped plugs that week, put a new fuel filter in it, and went back to the track the next saturday and ran 12's all day long....

I decided to cut the old filter in half after that because the truck was only a couple of weeks old and only had 1200 miles on it and I couldn't believe the filter could have been that bad even after getting the bad gas.

This is what I found
Pics do it no justice, it was filthy, the cleats were clogged dam near solid, there was fuzzy filthy crap everywhere, brown sandy dusty crap, & chunks of who knows what.... A real mess for a brand new vehicle with 1200 miles on it, all from one tank of crap from a top brand station I was using for years....
Bad%20Fuel%20Filtera.jpg
 
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Yeah, I'm gonna put in a new filter, plugs, get some ford racing plug wires and msd coil packs sometime soon but I pulled 5 of the plugs the other day and it ran better after that but still a little choppy. Crazy to think crap fuel can do that. Oh well live and learn right?
 

white95

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Not a big deal.. I have a similar issue, mine misfires for a bit then it stops and I drive it 80 miles a day
 

9838stang

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Fuel filter. Going past 50% throttle, and having that symptom I would assume you got bad gas and clogged or clogging the filter causing the car to buck
 
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Josef over here trying to give me a heart attack...but yeah you guys are all probably right. I've had the car for over 3 years now and I don't know when the og owner changed it. I know it's documented somewhere but I've gone about 33k miles since I've had the car and haven't changed the fuel filter yet.
 

96blak54

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Ethanol kills fuel filters. Sludges them up by breaking down the elements prematurely. Hopefully this isnt whats happened. The break down clogs the injectors. Your injectors will need replacing as well.

Their has been a few times I swear the gas I got had to be a greater ethanol mixture than 10% because the tank ran out at half the milage. Something like 30%...Maybe you got a mix like that? And if the car isnt set up for a heavy ethanol mix. Idk....just a thought.

Hope you figure it out
 
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[MENTION=19732]Ballistic[/MENTION] this may have some use for you too.

I'm gonna replace plugs next since I already took care of the filter and injectors but am still having the same issue. Does it give you guys any additional info knowing that it gets way worse when the ac is on?
 

Ballistic

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Ballistic this may have some use for you too.

I'm gonna replace plugs next since I already took care of the filter and injectors but am still having the same issue. Does it give you guys any additional info knowing that it gets way worse when the ac is on?

Kind of yeah, I think my plan is too replace spark plugs, spark plug wires, and if that doesn't do anything then coil packs then ill try injectors if the others dont work.

The no check engine light sucks and i cant really do anything until Tuesday with everyone closed..

Im still following you and your posts about this.
 

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