New plugs/wires/coil packs. Now lower mileage?
 

Hello everyone. First off Happy Thanksgiving to everyone here who celebrates it. Secondly my problem........

I took the truck in for an oil change and tire rotation about a month ago. After an hour and a half they finally finished. I took the truck home and it just didn't feel right. I've driven this truck for 10 years and put nearly 200k of my own miles on it. I know when it's "off". Couldn't set the emergency brake as the pedal would only move about a click or two. It worked fine before the tire rotation. :mad: Noticed a faint "ticking" sound also, but couldn't tell where it was coming from. Opened the hood and I could see a spark on the outside of one of the coil packs. "Well that explains it." I said and ordered new coil packs (2.3l Lima Ford. 4cyl, 8 plugs, 2 coil packs)and plugs and wires as neither had been changed in nearly 100k miles. Took the car to my regular mechanic (Who I completely trust. Very honest and very good people. We've used them for about 15 years now.) and gave them the new parts and had them check the emergency brakes. Cables were rusted up real bad so I had them replaced. The next two tanks I went from a 28 mpg average to about 21-22 mpg. I've had the truck back to the mechanic twice now (still trust him. He's just as stumped as I am.) Rear brakes aren't hanging up. Self adjusters are self adjusting fine. Replaced both front wheel bearings (They were originals. Almost 20 years old) Front calipers aren't stuck and no warped rotors. Replaced a worn lower ball joint. Was throwing a P0171 (lean condition) code so he smoke checked the intake and replaced a vacuum hose from the plenum to the purge sensor. Changed the fuel filter (Fram) and I thought I was good to go. Next tank was a little better at 24.5 mpg but still down from my 28 average. Same gas station as always too.

Still feels sluggish. I don't think it coasts as well as it used to, but it might just be my imagination because my mind is searching for possible problems. All four wheels are spinning about as free as they can be. Had full synthetic fluid put in the transmission, but that was about 120k miles ago. Full synthetic in the rear end too, about the same time.

If anyone has any other ideas to check I'm all ears. The obvious doesn't seem to be the problem (unless we've overlooked something stupid simple) so the more obscure ideas might be the answer.

Thanks for any help.

Stale gas- you haven't filled up for seven years.

LoL. I still have that leak in the filler neck so I haven't posted any solid numbers. I only drive to work and back on the same roads. Same mileage everyday. I pump gas until just shy of what I think it should take then pump slowly and watch for the first signs of drips. Then do the math. It's been a consistent 28mpg for a few years now. Larger tires and heavier rims took away about 1.5 mpg but better tires and I like the rims so the hit was worth it to me.

Winter?

I thought about that, but I only ever see about a 1-1.5 mpg drop with winter fuel. I also figured in the difference in miles with the larger diameter tires. Tires are 5% larger so I add 1 mile for every 20 miles driven. 5 for every 100.

If there is any fuel/air/ignition issue, it should throw a CEL.

Shouldn't take an hour and a half to change oil and rotate tires, they must have mokeyed with something. Check the alignment?

Check for brake dragging by driving fast for a while, then immediately park and put your hand near the wheels. You'll feel the heat from a dragging pad. My Acura has a tear in the lining of the parking brake that allows water in. When temperatures drop below freezing, the cable freezes in place, which is brake engaged.

That reminds me that I should dry out that cable and put a healthy amount of silicone sealant around it.

I drive 65 miles one way to work at 55-65 mph. Never feel any heat buildup from the wheels/rims or brakes. Truck doesn't seem to pull one way or the other. Not even under braking. I do catch a very faint smell from the right front when I get to work, but it's there and gone almost immediately. Not so much a hot smell like a bearing (just replaced the front ones) or dragging brakes, just odd. Reminds me of the hot Bake-O-Lite material that the old coil pack I replaced smelled like when I could see the spark on the outside of it.

Is there another emergency brake adjustment point near the pedal? I thought I read something about that at one time.

Checked tyre pressure?

That was my absolute first thought. The tire place ran them down to 32psi last time. I run them at around 40-42psi. Like they are now.

Full disclosure here. The tire place is NOT the same as my trusted mechanic.

If you smell something weird also check you pvc valve and hose, that smells like a faint burning if knocked off. I'd look at the vacuum lines and egr as well as long as you are poking around.

PS I just read your post better, I see you probably checked the lines if you replaced a hose. If you had the lean condition then a bad O2 sensor can cause that code. My brother's mazda had us stumped on that for awhile. He also threw a MAF sensor at it before we did the O2. Otherwise I would suspect a vacuum leak somewhere.

Wrong/heavier grade of oil put in?
As already suggested, alignment?
Perhaps your CAT decided to get plugged up when it wasn't firing right.

OK. If the battery was disconnected when the mechanic did the plugs and other stuff, does the computer (ECM?) pull a "return to defaults" trick? The last tank was actually better than my 28 mpg that I was used to. Only by a little, but better. This is what I had expected in the first place with new plugs and coil packs. Does the computer "re-learn" some sort of parameters after power is removed? Is this what I hear referred to as "fuel mapping"? Still going to have the alignment checked next week. In for a penny in for a pound.

Thanks for all the suggestions. I'll be back with some updates over the next few weeks.

Fill errors are a real thing but we can't tell your consistency from your fuel log.

I wish I had more data to give other than my word, but it's all I have. I drive the same route everyday. Very little (if any at all) "errand running". 120-130 miles a day/5 days (depending on the job site) a week for the last 20+ years. 10 years with the Ranger. Every time I fill up it's been within .25/gallon for the tank. A quart of fuel difference in a 12-13 gallon fill shouldn't be cause for too much concern. Before the new rim and tire combination I was doing better, but I have gotten a consistent 28mpg (+/- <1mpg) since the new "shoes".

Again, maybe the truck is having to re-learn something as I have seen improvement since the first abysmal 22mpg until now at a shade better than the 28mpg I was getting before all the work and re-work. I guess only time will tell at this point.