just some info before you read. the car misfires. it only does it at idle, when it's warm. the car has plenty of power. it was throwing a random misfire code awhile ago, but i've seen no ses light since. plugs, wires are good. after the car was seafoamed, i got good milage (about 25), before i was getting about 13. on the last quarter tank of 92 octane i only managed to pull out 20 mpg with 1/4 city, 3/4 hwy.

i've had this car for about a month and half now. i've had it looked at three times by two different dealerships with really no luck. i took the car on a thorough test drive, about 220 miles. after about 40 miles, i got an ses light. everything appeared to be normal and the car drove fine. i even got 27-28 mpg on the whole trip. i get back to the dealership and let them know about the ses light, never giving much thought too it. i get everything set up at the bank, and the day i go there to buy the car, i find out what it is. a random misfire. i was not happy, but the guy said it was just a couple old spark plugs, and they were replaced. so i make the huge mistake of signing the papers for the car, and then the piece of crap is mine. i had to work that same night and it was cold, so i started the car 10 minutes before i had to leave. i get out there and the nice little ses light is back on. i check in back and i can hear an audible misfire coming from the exhaust. about a week later i run the car back down to the original dealership (Ford) and they look at it, say it's probably a coil or injector, and tell me to take it to a GM shop. so i take it to the local chevy place. they tell me the same thing and add some techron to it, tell me to run the car and see if it gets better. i do just that and the misfire still persists. a few days later i take it back and i assume they seafoamed it. runs better for a few days, then the same problem. so i bring it up there again and they put more techron in, saying the injectors are a little sticky yet, but to run the car more. that brings me to now. i've run the car for probably 150 miles since then and had no problems until today. i stopped at wallyworld to buy a model (something to do during break). i put the car in park and notice it's vibrating a little, running kind of rough. so i went and back and checked the exhaust, sure enough it's missing. 30 miles later when i'm back home, i get out and check again. still missing. so i revved the thing 6 or 7 times. i went into the garage and opened up the door, talked to my mom a minute or so, then checked for the mis. i listened for almost a minute and i didn't hear it. it just pisses me off. the first time i test drove the car, i loved it. the way it rode, how it looked, even how the thing smelled. now, it just pisses me and i hate to even go in it. i always get the feeling something will go wrong (just replaced a wheel bearing). so i'm thinking i'll list the car in the local trading post, maybe i'll get an offer. i'd still have my good old buick waiting for me, always ran like a champ.

 

Since you had it a short time, I would take it back to the dealer and claim a lemon law for the problem since they can't figure it out.

 

i would love to do that, i'm not sure if i can though. is this an actual law, applicable in all states? god, i would love to just call them and say, you take this car back, and fix it till it's fixed, or give me my money.

 

In Ca. if you take it in 3 times for the same problem, yes then it will fall under the lemon law.

 

I beleive the lemon law only applies to new cars. A misfire is easy to find, theres only so many things to rule out before finding the cause. Take a look at it again before you give up on it.

 

frusciante fan when you got the car from the dealer did you sign any paper saying sold as-is?

 

it was sold with a 3-month/3,000 mile warranty.

 

So are you still within the warranty? If so, get paper work for everytime you take it in for those problem and save it for later time frame. When they cant fix a on going problem you will have proff that the car cant be fix and file a claim. Now every state might be diffrent so check into it.

 

Man, check and see at night, open your hood, start your car and see if any of your spark plug wires are arcing. Or, the wire running from your coil to your opti. Take a look.

 

by arcing do mean actually seeing a spark?

 

You need to be firm with the repair facilty.

I once bought a 5.7 Iroc that had chronic hard-start issues. The original owner had it looked at several times, but it was never repaired properly. After I got the car it bugged me so much I took it in. Again, they couldnt find anything wrong.

I took it back one more time. I gave them written detailed instructions on the symptoms and how best to reproduce them. I told them the car was "theirs" until thy fixed it. I didnt want to ever see the stupid thing again unless it started perfectly every time the key was turned.

They sensed my displeasure and actually did what I wanted. It ended up the burn-off relay for the MAF sensor was bad and the element was never getting clean. The element was constantly dirty and making it slow to start.

Problem solved!
You need to "lay the smack down".

 

Ditto....

 

Some stealerships wil screw you if the think you are "soft".They tried that with me about a month ago when I took thw SS in to have the window motor/regulator replaced.The window would not roll down all the way,and went up too far.They gave it back to me,and told me it was ok.After nutting up on the service writer and the service manager,they fixed it properly and knocked 90 bucks off the total.Don't let 'em screw you,you pay their friggin' salaries,not the other way around.

 

wow. i added a little bit of seafoam to the gas tank, about a 1/4 can. and drove a few miles. as soon as i got in i knew something was up, you can feel this unnatural vibration in the car. i ran the car hard and i can tell there is a power loss. i went full throttle from a dead stop and didn't even spin the tires. i just got back now and it's worse. i got out and there's a couple audible popping noises even few seconds. so i revved it a few times and let it idle for a minute or so. at last i checked the poofing sound is almost constant. and gas consumption, well it's using lots of gas.

 

if the wires are bad you'll see them lighting up in the worn places...
anyway, the problem you're describing sounds like a fuel/ignition problem. I don't know much about 4gen's, but in a 3gen i would have these things checked:
plugs
wires
coil
ignition module
Electronic spark control module
knock sensor
02 sensor
cap/rotor
possibly some of the other sensors like "Mass Air Pressure" and "Throttle position sensor".

first of all, tell the service guys to check the AIR TO FUEL RATIO, if it's either too rich or too lean u have proof that something is wrong with the car.