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Discussion Starter #1
Hi everyone!

Spent the last 2 days (!) reading over a ton of posts on performance; what a treasure-trove of information and advice on here!

I've had a 2007 FJ Trail Teams Edition for just over a year - love it; best vehicle I've owned!

Recently I've been having issues with gas mileage being really really really poor without any other adverse issues. After all the reading I've done, I'm going to check the Mass Air Flow sensor and the throttle body... hopefully cleaning those will make a difference. The last tank I ran, I got about 240km / 150 miles, running on 91 octane "super" gas, at 60 litres or 15 gallons per tank, that's what, about 10 miles per gallon!!! Anyway, I'm obviously hoping to resolve this issue quick. My FJ has a K&N air filter, which I cleaned myself using a K&N filter cleaning kit - I followed the directions at K&N Air Filter Cleaning Instructions but perhaps I oversprayed it with oil or something. Anyway any other suggestions would be very welcome!

Thanks!

Max
 

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:wave: Welcome to the forum.

I ran a K&N for about 10k miles and pulled it out and went back to oem type filters, the K&N passed to much dirt for my liking, I even greased the sealing surfaces, it all passed through the filtering medium. I didn't see any performance/fuel mileage increases so out it came. :cheers:
 

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Good to see another Winnipeg'er!

Welcome!

:cheers:

(Beers or coffee is in order at some point)
 

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What's your coolant temperature at when you've been driving it a while ? How many miles/kilometers on the beast ? Some have been having thermostats going bonkers allowing the engine to run too cold sucking up large amounts of fuel. Been cold out there lately. Yesterday was the coldest in recorded history in the city of Kingston Ontario. I wish I was in Kingston Jamaica right now.
 

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Discussion Starter #8 (Edited)
What's your coolant temperature at when you've been driving it a while ? How many miles/kilometers on the beast ? Some have been having thermostats going bonkers allowing the engine to run too cold sucking up large amounts of fuel. Been cold out there lately.
Yah, I'm not precisely sure what the coolant temp is; the FJ does warm up fairly quickly and pumps out tons of hot air - outside temps have been down to -30° recently - I'd think if there was a problem with the thermostat I'd have noticed - which leads me to believe it's not the thermostat. However, having said that I'm certainly going to be paying much more attention to that! I was thinking of getting some kind of ScanGaugeII trip computer, but not sure I want to shell out the $150+ if its not worth it...

She has 68,000 KM / 42,500 Miles on the clock.
 

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Discussion Starter #12
Welcome, there have been a few that have attributed bad mpg for bad thermostat. Might be worth checking into. As for the scangauge any local parts shop should be able to check it out for free, save yourself $150.
Good point! Thanks for the tip!
 

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Welcome!
 

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I've noticed a big drop in milage when it gets cold out. Yesterday it was -28 and I could really feel alot of drag with all the freezing cold gears trying to move. I switched all the fluids to synthetic a few years ago and it helps. The cold hydraulic fluid in the clutch made the pedal real slow to come back up.
 

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Discussion Starter #16
I've noticed a big drop in milage when it gets cold out. Yesterday it was -28 and I could really feel alot of drag with all the freezing cold gears trying to move. I switched all the fluids to synthetic a few years ago and it helps. The cold hydraulic fluid in the clutch made the pedal real slow to come back up.
My FJ is an automatic, so no clutch pedal (wife doesn't drive standard!)

For some reason that reminds of one other "weird" symptom; when I take my foot off the accelerator, my FJ slows down really quickly; almost like it has an engine brake or something...
 

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My FJ is an automatic, so no clutch pedal (wife doesn't drive standard!)

For some reason that reminds of one other "weird" symptom; when I take my foot off the accelerator, my FJ slows down really quickly; almost like it has an engine brake or something...
Was it better today with the warmer weather?

Are you running full synthetic in the diffs?
 

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For some reason that reminds of one other "weird" symptom; when I take my foot off the accelerator, my FJ slows down really quickly; almost like it has an engine brake or something...
I think I read somewhere that the ECM (engine control module) takes into account the throttle position when selecting a gear and will downshift quicker if there is zero input from the throttle.

I tried to find where I read that but can't find it.... so there's no guarantee on my accuracy ;)
 

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Yah, I'm not precisely sure what the coolant temp is; the FJ does warm up fairly quickly and pumps out tons of hot air - outside temps have been down to -30° recently - I'd think if there was a problem with the thermostat I'd have noticed - which leads me to believe it's not the thermostat. However, having said that I'm certainly going to be paying much more attention to that! I was thinking of getting some kind of ScanGaugeII trip computer, but not sure I want to shell out the $150+ if its not worth it...

She has 68,000 KM / 42,500 Miles on the clock.
I just took delivery of a ScanGauge II for the same reasons you're troubleshooting. Poor fuel mileage. I posted a thread when I was questioning my cold start to full running temp and the suggestion to get the ScanGauge II intrigued me. I was messing with it earlier after work and later reading the booklet for setting it up and selecting what I want to display. I'm thinking I might have had a slow to close thermostat and I wasn't coming up to full temp, thus it was dumping lots of fuel into the engine. However after a long trip into the mountains a couple weekends ago, it seems to be better. Could be my imagination though. Tomorrow I'll be running the wire permanently and mounting it right over the steering column, where it will fit real nicely. I plan to monitor coolant temp and and mpg as well as some other info. It'll be nice to have some real gauge feedback rather than those overly simplistic gauges.
 

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Discussion Starter #20
I just took delivery of a ScanGauge II for the same reasons you're troubleshooting. Poor fuel mileage. I posted a thread when I was questioning my cold start to full running temp and the suggestion to get the ScanGauge II intrigued me. I was messing with it earlier after work and later reading the booklet for setting it up and selecting what I want to display. I'm thinking I might have had a slow to close thermostat and I wasn't coming up to full temp, thus it was dumping lots of fuel into the engine. However after a long trip into the mountains a couple weekends ago, it seems to be better. Could be my imagination though. Tomorrow I'll be running the wire permanently and mounting it right over the steering column, where it will fit real nicely. I plan to monitor coolant temp and and mpg as well as some other info. It'll be nice to have some real gauge feedback rather than those overly simplistic gauges.
Cool, Froader; it'll be interesting to see what you think of it...
 
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