Ok like it says I have a 06 s197 started misfiring only above 4500 WOT and had 30 miles to empty . Called a friend told me might be bad gas I went and put 25 bucks in it and missed a lot lot less. To night went down to 30 to empty and same thing . Could this really be bad gas ? I changed the plugs 1 1/2 ago and car is tuned by millaro in SA .

 

If your saying you had 30 miles till empty. The fuel pump is having trouble picking up the fuel remaining fuel in the tank because it's so low, something about the design. I was told by a tuner you shouldn't go WOT with less than 1/4 tank fuel, possibility of starving the engine of fuel.

 

First off, I would check/replace your fuel filter. Here's a thread discussing where it is and how to do it. If you've never replaced it, that's the first thing I would do.

Secondly, your sig line isn't very descriptive. I assume you have a Kenn Bell supercharger? If so, are you also running a BAP? In any boosted application, as already mentioned, I wouldn't go below a 1/4 tank and do any WOT driving. I would keep the shifts below 5k until you put more fuel in the car.

 

2.6 kenne bell full bolt ons and BAP . I was thinking fuel filter too I am going to do that today . I usually don't run her hard with less than 60 miles to E . I just do happen to give her alittle extra .

 

Fuel filter changed fesh tank of gas still doing it not as bad

 

Pull your plugs
Check vaccum lines
Wideband? What's it say?
Reload tune?

 

Vac is good and wide band looks normal. Not throwing a code for sparks . I was dreading having to pull them again . New air filter . And I am going to reload the tune

 

Sounds like you may have a bunch of sediment build up in the tank- I've seen on much older cars that as the fuel level gets lower, the pump has a tougher time dealing with all the sediment build up and struggles below 1/4 tank of gas.

Might be worth taking a peak in your case.

 

There was a TSB about the fuel pumps in 05-06, you may require a new one. Hopefully you have somekind of extended warranty to cover the cost.

 

I would run that thing until the tank was empty and then fill up with good fuel. i got a bad tank of race fuel one time and took 5-6 fill ups with other fuel to cure the issue.

Your car can idle in the garage and run until there is no fuel left. Whenever i switch over to race fuel I drain fuel with an inline drain and just let the pumps pump all the fuel into a seperate gas can until I hear the car start to stumble and miss.

I have a KB, built motor and 16 psi. Been doing for years with no problems.