Ben Kearns

I have a 06 4.2L v6 with a 5 speed manual 2wd. what are you guys getting for fuel mileage? I bought it about 4 months ago and it had 87,000 miles from a dealership and I know it was crashed but he says no! But i noticed the check engine light was disconnected so I plugged it in and was pulling 2 codes. Fuel rail pressure sensor (to high or to low), and inertia switch, so i installed a new f.r.p.s. and had the codes erased. The next day it was pulling them again and the fuel pump was making a weird noise too so I changed that. still the same thing then i read something on here about the fuel pump driver moduals corroding out and sure mine was and whoever owned it before me just grounded out the one wire and the fuel pump was pushing 90 psi so i put a new f.p.d.m. and put wires back to the way they are supposed to be and am getting 35 psi. The truck runs great but it idials rough and and when im cruising with my foot barely on the gas it ticks really bad. I have tried everything and cant figure it out, I GET 11-13 mpg with a v6 and a 5 speed driving like a baby. Plus i had it completely tuned up new plugs, filters, oil change, the works.
Whats going on? Bad O2 sensors, what?

fleetnuts

I have an 08 2wd reg cab with the 4.2 V6 and I get 13 on average in the city. But I also upgraded from the cheap 235/70/17 to a set of 265/80/17 Goodyear AT/S. and about 16 on the highway doing 70 - 80 lol

cubapnea

1: what brand of plugs did you installed?
2: did you cleaned the throtle body?
3: how good is your coil pack?
4: did you change/check your plug wires?

This is all basic fundamental stuff and can be done easily by yourself. I gapped my plugs at 0.53

meceres

I have a 2005 automatic. Changed plugs with oem, k&n intake. I have 265/70/17 and I am getting about 11-13 mpgs on city. I don't do a lot of highway so I am not sure how my mpgs are on highway.

cubapnea

^^ that's bad... I have an automatic with 285/65/18 electric fans ...doing 16 mpg city.

meceres

Did you change your speedometer to accommodate for larger tires? What is helping you to get 16 mpg, is it the electric fan making a difference?

Toys-N-Joys

i get about 17mpg with my 4.2 4x4 2004 heritage automatic. i dont drive like a racer and if i am parked for extended periods i shut the truck off. ease onto the gas pedal and look up driving tips for mpg.

also low mpg could be due to lack of maintance. new filters and lubes help. new bearings help too.

some good info posted above too

cubapnea

Yeah I adjusted speedo with a diablo programer..driving habits helps with gas savings but it looks to me you need to check your truck.

meceres

What do you suggest? I replaced the spark plugs at 60 k, right now I have 70k. Perhaps change the cables? Oil is changed on time

cubapnea

Clean throtle body and replace fuel filter..you can sea foam your engine...search on this forum for info on how to procedures