Shaking at Low RPM and horrific gas mileage (beginner)

**LeoSpencer** · 11-28-2013

I have a 2006 3.8L Supercharged with 145k miles on it. I've never been car or engine savvy (I can change basic things that require basic tools) but I'm trying to figure this out before I start throwing money where I don't need to. At low RPMs and idle, the car has a bit of a shake to it that peaks around 2k and quickly tapers off. There is also a sputter from the exhaust that was never there before. On top of that, I've getting around 7 mpg and giving the car any bit of gas dumps the instant economy down to 1 or 2 mpg. My first thought, and by quick internet search, was to change the spark plugs and/or wires. However I'm not sure those specifically would affect the fuel economy of the car. The SES light is blinking

**Scottydoggs** · 11-28-2013

if its never been tuned up, start there, plugs and wires. (get iridium spark plugs)

oil change, coolant flush, trans service, pan drop and filter only, (dont get it flushed) and fuel filter should all be done soon too.

get your own records on your fluids. lord only knows when or if these fluids were ever changed.

old plugs can cause what your describing. like a shuddering loss of power. then clear up at higher rpm's.

theres lots of how to's here, most of the repairs on these cars can be done will little more then a 30 piece socket set some wrenches and screw drivers.

**indygrandprix** · 11-28-2013

Don't forget to clean your injectors too. Get a good cleaner either one from the dealer or a brand called Techron. All that other stuff is mostly a bunch of crap and won't do much.

Also if you put your foot into the gas really hard when cruising does the car sputter and chug? (That would be another indication of bad plugs/wires)

The flashing SES light is indicating that you have a Catalyst Damaging Misfire. If you could go get the codes read that would help us help you out more.