Quick injector question

VEE EIGHT said:

Within the last month or so, my GT has been getting HORRIBLE gas mileage. I'm talking about around 12 mpg, which it never used to be. I bought the car about 3 months ago and other than the dealer-performed oil change, I have no idea what kind of maintenance the previous owner(s) performed. The car just hit 60K miles and was wondering of changing the injectors would help (thinking they might be really gunked up and trashed).

Anyway, I have no idea what kind of injectors I have or how much they run. Can anyone help me with this?

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I'd strongly advise against just throwing parts at it (e.g. replacing fuel injectors) without having a full and proper diagnosis done.

What mods are on the car? What was the fuel mileage before you noticed the drop? You're getting 12MPG now: What sort of driving conditions does the car see: City? Highway? Mixed - 75/25, 50/50, 25/75?

For diagnosis, I'd start by getting a good scanner on it. Check the codes: Is the MIL on right now or has it come on since this poor mileage condition started? It'd be nice if the scan tool had the ability to show the forward O2 sensor activity real-time (e.g. in graph form...some PC-based tools do this, not sure about handhelds...) You want to see what the O2 sensors are doing during normal driving. They should move rapidly between rich (>450mV) and lean (<450mV) as the PCM trims the fuel delivery. It'd also show you fuel pressure...

What color are the spark plugs? Are the tailpipes covered deeply in soot?

Are any of the brakes dragging at all? Parking brake operation and cables okay?

You sure there's no fuel leaks anywhere?