JBurt
Senior Member
So this is not a plug for a hydrogen generator or any crackpot ideas. I've been getting 11-13 mpg since I bought my rig. I haven't been in a big rush to fix this since we also have a Prius and we drive that when we go anywhere far away. I know I drive a truck but I feel I should get at least 16mpg's. I think that is in reach.
Anyways there are so many threads out there where people ask why their mileage is bad and everyone says search. While there are lots of good suggestions out there I thought what I'd do here was put links to write ups for things that actually do keep you're truck in good working order. I'll keep this first post updated with current procedures and links. I'll start off with the ones I've done and go from there. Anyone feel free to chime in and add some good input. If you've got a better write up I'm happy to change them. Some may not have links at first. A lot of the ones I used are now gone. Hopefully this will help me and some other people. Too bad 4runners.org is down. There was good stuff on there.
Clean MAF
Change sparkplugs
Change upstream o2 sensor
Clean Throttle Body/Idle Air Control Valve
Compression Test/Leak down test
Replace fuel filter
No write ups because they are really easy.
Replace air filter
Replace PCV Valve (pull out old valve and grommet, push in new)
Check tire pressure
Sludge and a dirty top end can also be a problem. There are a few ways to tackle this:
Seafoam
Brute force
A clogged catalytic converter can also cause bad mpg's and severe power loss. One way to check is to remove the upstream o2 sensor to vent exhaust to atmosphere before the cat and see if there is a power gain. That means you cat is clogged.
Bad fuel injectors are also a cause. Replacing is kind of a pain. There are services like witch hunter that will rebuild if possible for much less than a new oem one. Here is a guide to replacement. Anyone know of a way to test them without pulling them out of the vehicle? You can also put fuel injector cleaner in your gas tank. Seems everyone has their favorite.
Exhaust leaks - you can check by doing the above mentioned seafoam treatment, then when your rig is spewing smoke look under the car to see if smoke is coming out from anywhere else.
After you do any of these you should reset you're ecu. To do that either use a computer or disconnect the battery for 15 minutes. The engine will go through a diagnostic mode for 80 miles or so. After the diagnostic mode you'll know if you fixed it.
You should also add that a bad alignment could be a cause. The types of mods we tend to do play a role as well (lifts, wider, more aggressive tires, roof basket, etc.).
Bad electrical connections could be a cause as well. Make sure to clean the battert posts, make sure there are no inadvertent grounds, all connections are complete, etc. Not sure if the spark plug link says it, but changing the wires is a good idea also.
Anyways there are so many threads out there where people ask why their mileage is bad and everyone says search. While there are lots of good suggestions out there I thought what I'd do here was put links to write ups for things that actually do keep you're truck in good working order. I'll keep this first post updated with current procedures and links. I'll start off with the ones I've done and go from there. Anyone feel free to chime in and add some good input. If you've got a better write up I'm happy to change them. Some may not have links at first. A lot of the ones I used are now gone. Hopefully this will help me and some other people. Too bad 4runners.org is down. There was good stuff on there.
Clean MAF
Change sparkplugs
Change upstream o2 sensor
Clean Throttle Body/Idle Air Control Valve
Compression Test/Leak down test
Replace fuel filter
No write ups because they are really easy.
Replace air filter
Replace PCV Valve (pull out old valve and grommet, push in new)
Check tire pressure
Sludge and a dirty top end can also be a problem. There are a few ways to tackle this:
Seafoam
Brute force
A clogged catalytic converter can also cause bad mpg's and severe power loss. One way to check is to remove the upstream o2 sensor to vent exhaust to atmosphere before the cat and see if there is a power gain. That means you cat is clogged.
Bad fuel injectors are also a cause. Replacing is kind of a pain. There are services like witch hunter that will rebuild if possible for much less than a new oem one. Here is a guide to replacement. Anyone know of a way to test them without pulling them out of the vehicle? You can also put fuel injector cleaner in your gas tank. Seems everyone has their favorite.
Exhaust leaks - you can check by doing the above mentioned seafoam treatment, then when your rig is spewing smoke look under the car to see if smoke is coming out from anywhere else.
After you do any of these you should reset you're ecu. To do that either use a computer or disconnect the battery for 15 minutes. The engine will go through a diagnostic mode for 80 miles or so. After the diagnostic mode you'll know if you fixed it.
You should also add that a bad alignment could be a cause. The types of mods we tend to do play a role as well (lifts, wider, more aggressive tires, roof basket, etc.).
Bad electrical connections could be a cause as well. Make sure to clean the battert posts, make sure there are no inadvertent grounds, all connections are complete, etc. Not sure if the spark plug link says it, but changing the wires is a good idea also.
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