Okay, so I'm a female (recently divorced) who now has to take care of her own car, a 99 Eclipse GST. I put a different brand of gas in 2 days ago and since then it feels like it's going to die when I'm idling. A friend came over and took a look and said it's misfiring which could be several things and should just start with process of elimination. He recommended starting with new wires/plugs and if that's not it, new injector(s)? I decided to go back one step further and try a different gas. I normally burn mid grade (Octane 87) but went to Chevron and put in the Techron Supreme hoping it might clean gummed up injector? I'm at a loss and hoping this is something simple I can handle...any ideas?

 

try some 91 octance and lucas injector cleaner. If that doesnt work, go for new plugs and wires

 

All right first off go to the auto store and get some fuel system cleaner. With a GST you should be running a higher grade of fuel in the first place. ANY turbo charged car requires a higher octane rating. Now for the missfire... With the hood open see if you can hear an odd sound at a regular interval. That will give you an idea if there is a misfire somewhere. I myself would then pull a plug wire to see if there is an affect on the engine's running then plug it back in and go to the next plug wire (Of course while the engine is running but I'm crazy like that and don't expect YOU to do similar cuz you CAN get a rather nasty shock if you touch the wrong area or pull it off the coil instead of the spark plug, or if there is a bad wire.). Also start the car at dusk or when it's dark and open the hood. See if you can see a nice little blue light at a regular interval as well. That would indicate a bad plug wire (Arcing someonewhere other than the spark plug). If you see it then replace wires. (I had my #4 wire arcing to the #3 cylinder for a while myself).

Hopefully this all helps but any other questions feel free to ask.

 

sang your gonna get her shocked. lol. but Yea thats a good way to test the coil pack and wires. (even tho there are safer ways)lol

 

The friend that came over to take a look at it today had this little diagnostic meter thing (I know, go ahead and laugh at me..I'm a girl! lol) and it told him I had a misfire...I could've swore he said in cylinder #3...does that make sense? After I put in the higher octane gas, it sputtered like in cycles, not constant like it had been doing. But if it's okay to use a fuel injector cleaner in a turbo engine, then I will try that...

 

he had a multi meter. that would be my guess. And yes you should put some injector cleaner through it along with high grade gas.

 

Yeah get dome gas tank additive fuel system cleaner and if it's #3 misfiring then change the wires first along with the plugs. If THAT doesn't fix it then you'll be looking at replacing the coil pack.

 

I'm not flaming the original poster or anything, but Premium is on the Tachometer or in the fuel fill door. Nothing lower than Premium should have been put in..at all.
Personally, I would go straight for the jugular and change out the plugs and wires. Making sure that the plugs are gapped correctly at .028.
I tend to think that from running lower than recommended octane, the plugs are probably fouled up not, to mention the ECU needs to relearn it's timing. The old plugs probably lost it's gapping too. Anyway, that's just me. I understand that you (original poster) may not "know" about cars, but we're here to help....just stop using low octane gas on a turbo car. 89 octane and below are for naturally asperated cars or non performance cars.

 

Oh yeah, I forgot that the o2 sensors are probably covered in blackness. If you're experiencing low milage, there's one culprit, the other is a clogged EGR valve.

 

^^exactly. anything lower than 91 octane is bad. I recommend always using 93 if you can.