theory on why gas milage is bad

[BlackGT97]

Last summer I did a full tune up on my car ( plugs, wires, fuel and air filter, trans fluid and filter). So looking on it now, I put NGK copper plugs in (TR55s). The heat range is 5 and the stock heat range calls for a #4.

Could this be why I lost 120 miles/tank?

[Fivefingerdeathpunch]

Doubtful. Copper plugs do die about 12-15k miles, and I would run AL 606's. I honestly dont have a clue as to what NGK's are for stock and colder plugs.

But losing 120 miles a tank, cant all be blamed on the spark plugs.

[ctracer]

120 miles a tank? i dont think that can be JUST plugs. and why you running those plugs anyways?

[BlackGT97]

I was unaware of different heat ranges. Plus the engine was stumbling and I didn't know if it was the plugs, so I just purchased a cheap plug.

[matt5112]

3k for a set of coppers.before the idle started to get rough.

[BlackGT97]

3k for a set of coppers.before the idle started to get rough.

What?

[matt5112]

What?

What?

[BlackGT97]

lol, im not sure I get what your saying. Are you saying copper plugs screwed your car up and cost you 3k to fix?

[ctracer]

im pretty sure hes saying that it took 3k miles for them to start missing