Normally I get all the info I need from older threads on here , but this time I'm at a loss with what could be causing a few issues with my 06 4.7L QC 4x4, so I guess I'll bounce the situation off you guys. I have a feeling I'm losing mpgs right now.

Bone stock motor at 71k, general maintenance/tuneup was done about 20k ago, minus a recent air filter on my last oil change. Running the Autolite 3923 plugs as suggested on here. Run syn motor oil and a good filter, change every 5k. Last two summertime MPGs averaged about 17.5 20/80 city/hw (70-75mph on a 30mile one-way commute). Around Nov., noticed my MPGs dropped to about 15 same driving conditions, which I figure is just normal for winter blend, as is on par with last Nov./Dec.

Since the end of Dec., though, I have been pulling 13 tops and average 12mpg with same driving conditions, no codes are being thrown either.

Replaced struts and shocks with Ranchos about September, and just replaced the entire front end basically with a NAPA lifetime wheel bearing on one side, MOOG ball joints/Control Arms, and Autozone lifetime tie rod ends. Had an alignment done right after.

I figured it was just a bad tank of gas from the place I fill up at all the time, but when it continued for a few tanks after that, and continued when I switched to a different brand, it started me thinking.

Something else it does, it seems to have a little intermittent idle "vibration" I guess would be the best word to describe it, but I think that is the IAC if I remember the thread on here correctly. It also sometimes intermittently slows down 1-2mph when cruising on the eway, enough to make your body shift forward slightly.

Sorry for the long post, but I wanted to put out all the info I had so far so you guys don't have to ask me a million questions to get the relevant info. I know its a truck and not supposed to get huge mpg totals, but I would love to get back to original mpgs if possible.

Thanks, Matt

 

Prolly should add I am in MI, and fire my truck up w/ remote start 2-3 mins the first time for the day before I get in it and go. No different than last year's winter habits.

 

That sounds pretty normal. Winter gas sucks. I am sitting at 15 mpg city, and in the summer I am around 20 mpg city. A lot of places are getting away with adding more ethanol to our gas, 10% is the max set by the government. I would wait till the summer comes back to make sure. In the mean time, you can make sure your TB is clean, and run some Seafoam in the gas tank if you like using that stuff.

 

I've ran Seafoam through the tank, no difference. I have another one sitting on the shelf when I get time to run some through the vacuum line and make yet another YouTube smokescreen video......lmao. Its supposed to warm up this week, so I'll probably go clean out the TB and pull the plugs and verify the gaps are still set right.

Its just weird that it all happened right around the time the front end stuff let loose.

 

Other items to check, snow in the bed add weight, tire pressure not correct, tires unbalanced.

 

None of that is the problem, bed is covered, and tires were aired up, balanced, and rotated when the alignment was done a few weeks back, pressure was checked earlier today.

I thought O2 maybe, but no code is showing. Unless it is getting lazy with age. Or its just that I am getting down to normal Dak numbers now......damn.

Good thing I'm moving about 5 mins away from work this week, should help keep me from dumping $60 every 2-3 days into this thing for petrol from now on.

 

Jack er up and make sure those wheels turn free. I know how you northern folks have rust and crud issues.

 

I've had lazy O2 sensors not throw codes but noticeably affect fuel consumption. Might be worth looking into if nothing else comes up.

 

my mileage sucks...my first winter with a vehicle i have really noticed the difference (cause of that d@mn overhead thing telling me my mpg)....i was averaging 18-19 when I got her over the summer....16 now...cant wait for spring....

 

Is that how to tell if you need a wheel bearing?