My 99 ranger gets bad mileage and I've skimmed through a couple of threads already over this issue. My gas gauge likes to hang and my tires aren't stock so I'm not able to get an accurate reading on mileage. I've got a miss or two I'm already looking into fixing. I'd seen quiet a few people mention tuners but I know literally nothing on those so any pointers on how they work or whatever would be great. I work about 17 miles away from my house, bout a 30 minute drive. Money's tight so I usually just put 10 in the tank every other day. That usually brings it up by a quarter tank but it's gone in just two days of work. Mostly use it for work at the moment if anything else take it to the store a few miles up the road. I already know I need to change plugs and wires, air filter, and oil. If more information is needed on my tires and anything else on the truck I'll be happy to answer if it leads to some sort of improvements.

 

17 miles to work = 34 miles round trip, 68 miles every 2 days,
$10 = almost 4.5 gallons every 2 days

68/4.5 = 15 mpg

On such short trips with your 3.0 you're actually doing pretty good.

 

Manual or automatic?

It takes engine about 5 minutes to warm up when driving, 8 minutes idling, only after warm up do you get best MPG
Temp gauge should be just under 1/2 after warm up, if lower then you have a stuck or the wrong thermostat, some people use 180deg t-stat, which reduces MPG, Rangers used 190-195deg t-stats

The 3.0l is a HIGH RPM engine, so automatics with this engine suck gas big time

15MPG wouldn't be "bad"

Change the plugs and you may get closer to 17

You are driving a pickup truck with horrible air flow, and WIDE tires, also running an engine that was designed in 1985, so 35 year old technology

 

Thank you for explaining that. I'm pretty bad at figuring gas mileage especially given my gauge likes to stick and didn't think to break it down like that. Also my ranger is an automatic and as soon as I can change the plug wires and spark plugs I'm definitely going to. Would a higher end air filter really help it any or is that a super small boost in mpg? At the very least I'll get a new air filter. The trucks also got over 400k miles which is a pretty important thing to mention I'm sure that I completely forgot about. The trucks probably real close to being on it's last leg so I'm not trying to invest too much money on it right now.

 

Stock Ranger air filter has 200% flow so as long as its reasonably clean its not an issue

If Upstream O2 sensors are over 100k miles then change them, as they get older they run low on the chemicals to detect Oxygen in the exhaust causing computer to run engine Richer than needed

 

Well I was told having an empty catalytic converter will cause the o2 sensor to read bad no matter what. I keep forgetting pieces of information like that and that's my bad.

 

Empty Cats won't cause any change in MPG as far as upstream O2 sensors are concerned

Downstream sensor would cause a code to be set because Cats are not cleaning up exhaust and computer may add a bit more fuel than needed to try and get the Cats hotter

Cat converts need unburn gasoline to get hot enough to clean the emissions, so computer sends a Rich mix every few RPMs to keep Cats hot, rear/downstream O2 tells the computer how much oxygen is in the exhaust after the Cats, should be very little since its burned up when Cats burn the gasoline

O2 sensors generate their own voltage
.1 volt is Lean, high oxygen level
.9 volt is Rich, low oxygen level

Upstream O2s run at about .4volts, the sweet spot for a good burn in the cylinders
Downstream O2 would run at .7-.8 volts because the oxygen is used up

With no Cats the Oxygen level would be same as upstream since Cats are not working
So it sets a code

 

I replaces the air filter,. Changed the plugs and wires, and oil. MPG had a noticeable increase which I'm really happy for. Been a week or so since I did everything so I'm kinda late to responding for that I'm sorry. Next step for me and my ranger is to save up for a new transmission. That bugger been slipping since I got it in 18. Getting worse now so I figure it's about to go out.
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