Not even 2 minutes of filling up the tank + lucas fuel treatment I began to notice a misfire at idle.

I did drive all the way to montauk point, ny 2 days ago, a total of 125mi of travel.
Drove fine, Had a little fun with it & got a good feel of how the car drives at higher speeds.
Now today I decided "hey long drive, add lucas!" cause of its lubricants. And what do ya know...its got a misfire ):
Check engine light has not come on yet.
I go to the same mobil gas station were I live, premium fuel...Everything has been changed since I got the car. (fuel filter included)

Any ideas?

 

When you added the fuel treatment did you add it to a full tank of gas?

The only thing I can think of it could have affected is a plug or an injector. You may try running it until you are down to have a tank and add more gas and see if it clears up. Or you can try pulling the plugs and checking them.

 

yes it was added first before I filled up.
I go through gas like its nothing(due to lots of daily miles) so I'll see results in a day or too..

I wouldn't think it would show up on the spark plugs yet. It wasn't even 2 miles of driving afterward.

 

I love to hate lucas products. But I have more of a feeling that is is just coincidence and you have another problem.

 

I think it's coincidence myself. I've never used Lucas, but I've thrown in other "fuel system" cleaners (since the Monte sits during winter, I normally throw a bottle of cleaner in after I burn off the tank with the fuel stabilizer in it). I don't know if it does any good or not, but I figure it won't hurt (I've usually used the el-cheapo STP stuff).

It should not matter if you have a full tank or not when you put these cleaners in, as they are normally the best/cleanest burning thing you can put in the tank (better then gasoline itself).

I would consider, how old are the plugs? How many miles are on them?

I just changed the plugs/wires and cleaned-re-oiled my K&N air filter on my '94 Grand Am (it began loosing noticeable performance and the idle had a slight change that since I drive the car all the time, only I'd notice). After all that work yesterday she runs GREAT again. Not bad for pushing 220,000 miles.

 

Some fuel additives help to disipate water accumulation by allowing it to mix with the fuel and pass through the fuel system. It's also possible that the detergents in the additive dislodged a piece of crud that is now interfering with injector operation. Take the car out onto the freeway and give the engine a couple of good pulls every now and again while burning through this tank of fuel and see if it doesn't clear up with your next tank full.

 

Like others have said Give it a tank or two of gas, see if it throws any codes at you and go from there. maybe you have a loose plug wire.

 

The car is only 50k, alot is still original (spark plugs, wires, exc) So they really don't need changing at this moment. Will be changing them soon though.

I have noticed it ran a little better after sitting over night. I guess all it needed was to sit with the lucas for all the gunk to break down.

 

Umm, if you have a problem such as a misfire, you can't just look over a part due to its miles. Everything and anything can fail.

 

May be unlikely at 50K that plugs and wires are to blame, but not out of the question. As aussiek2000 points out, if your having a problem, the mileage should not become a reason to over look something.

But, it is good to hear after sitting, you have noticed an improvement. Hopefully that one situation was the ONLY situation of mis-firing and that it will all become just a memory.