Poor fuel economy ? Start with the simple things

[doode]

So I have a 1999.5 3.3 liter that used to get me around 14 -15 mpg.

About a year ago fuel economy started to drop and until finally I was getting 11 mpg.

I tried everything but it still sucked : tire pressure, oil change, air filter, cleaned the MAF, changed all the O2 sensors, fuel filter, fuel injector cleaner

Finally it dawned on me...spark plugs maybe ?



Those are base copper ones that are only good for around 30k.

I have 48k on them. Plug 6 was so fouled with carbon the tip and electrode were literally connected with carbon build up. I'm surprised I never got a CEL.

Plug 6 was still a struggle but I'm getting good at it and it only took me about 30 mins to re/re .

I did plugs, rotor and cap and now I am back to 14 mpg on crappy winter gas. I'm happy.

Just thought i'd share .

[vonscorpio]

I've been getting laughably poor mileage (12 mpg is the best I've ever seen, 11 average) out of my 2001 QX4, and I replaced the plugs late summer. Haven't touched the MAF or fuel filter yet.
What is considered normal for the 2001 (3.5 liter) that never is driven on the freeway?

[jiannichan]

I have a 2000 3.3L. This QX4 was my first time owning an SUV so I wasn't sure the mileage I should have been getting . I have owned plenty of i4 and a couple V6 vehicles and they got about 300+ miles per tank. I was a little concerned that I was at 240 miles when the light would come on and thought something was wrong. I was comparing V6 to V6 and didn't put into account the QX4 weighed 1000lbs more. I need to change my plugs, cap/rotor. Maybe I will do that this weekend. Thanks for the reminder!