9.7mpg on last tank.
is looking for his torque
Joined: Sep 2008
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Yeah my motor has only 6k on it and I put the BHR kit on right after the new motor was installed. I also switched back to a stock WIX air filter and ditched the K&N drop in. I am also OCD about tire pressures and stuff. I only run Shell 93 octane fuel, nothing else. I am also running 245/40-18 tires which supposedly hurts MPG. Keep in mind that when I am on the highway I also use the cruise 90% of the time if there is no traffic. In the city I tend to drive aggressively which is why there is a 5MPG difference.
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Joined: Jul 2004
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From: Northern California
Yes that is expected it's still a rich mixture warming up. I would imagine your plugs have a pretty black coat on them. Whats the history on your car?
wow, i nearly forgot how much better mine is these days. i used to get the usual 17-20mpg highway. not anymore...
recently in germany i spent a fair bit of time at high speeds. i was getting ~21mpg with nearly all of the driving time done at 6000rpm cruising in 6th gear. (thats ~120mph/200kph btw)
I consistantly get 20-22 around home here. almost 100% city/suburban driving, always in the throttle, plus the car doesnt move until water temps reach 170F. that means a lot of idle time every morning and a fair bit throughout the day on warm starts.
I never recorded exact numbers when i was in the states, but i made a 5 hour drive to Atlanta and based on some solid comparative info and common sense, I think cruising in the 75mph range - I am getting 26-27mpg.
I saw posts saying typical 250 miles to a tank... ugh.. my dash is in kilometers now, but last time i switched it to see at fillup i was at 308 miles(fillup was just over 50 liters, around 13.5 gallons)
I havent done anything crazy either. keep good plugs/wires, keep the MAF clean, clean filter etc. I have BHR coils, MM's AP calibrations, and no cat-converter. MS catback isnt significant, but i am hauling around ~70lbs in the trunk(bolted in audio equip)
I've around 45-50K miles. MAF numbers still well into the 220's and hopefully soon(this weekend) i'll get around to plugging in the compression tester for legitimate health review.
recently in germany i spent a fair bit of time at high speeds. i was getting ~21mpg with nearly all of the driving time done at 6000rpm cruising in 6th gear. (thats ~120mph/200kph btw)
I consistantly get 20-22 around home here. almost 100% city/suburban driving, always in the throttle, plus the car doesnt move until water temps reach 170F. that means a lot of idle time every morning and a fair bit throughout the day on warm starts.
I never recorded exact numbers when i was in the states, but i made a 5 hour drive to Atlanta and based on some solid comparative info and common sense, I think cruising in the 75mph range - I am getting 26-27mpg.
I saw posts saying typical 250 miles to a tank... ugh.. my dash is in kilometers now, but last time i switched it to see at fillup i was at 308 miles(fillup was just over 50 liters, around 13.5 gallons)
I havent done anything crazy either. keep good plugs/wires, keep the MAF clean, clean filter etc. I have BHR coils, MM's AP calibrations, and no cat-converter. MS catback isnt significant, but i am hauling around ~70lbs in the trunk(bolted in audio equip)
I've around 45-50K miles. MAF numbers still well into the 220's and hopefully soon(this weekend) i'll get around to plugging in the compression tester for legitimate health review.
Last edited by paulmasoner; Dec 7, 2009 at 07:43 AM.
I normally fill up when the light comes on and thats around 310-320 miles on the tank. usually use about 12.5 to 13 gallons to get that. I know I could get another 30 to 40 miles once the light comes on.
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Joined: Nov 2008
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From: Boston
WOW! You get 310-320 Miles on a tank?? Id be LUCKY to get around 230 on a tank! THAT doesnt even happen! I do have an Injen intake and a catless pip and a Greddy SP2 Catback though.. Im sure those come in to play..
The truth about your horrible mileage
Honestly: If you have good compression.... and you still have this horrible mileage, you have maintenance issues.
In no particular order:
Coils, plugs, wires, fuel injectors, tuning, air filter, MAF sensor
If you have no other major issues - ie clogged cat etc - then you should easily be able to achieve 18-20mpg mixed driving.
In no particular order:
Coils, plugs, wires, fuel injectors, tuning, air filter, MAF sensor
If you have no other major issues - ie clogged cat etc - then you should easily be able to achieve 18-20mpg mixed driving.
Administrator
Joined: Jul 2002
Posts: 21,958
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From: portland oregon
what paul said- Hi paul!
the difference from 190 to 230 on a clean car is shifting. period.
the difference from 230 to 320 is the 320 is done completely on the highway at a steady speed less than 80mph from the beginning of the tank to the end.
the difference from 190 to 230 on a clean car is shifting. period.
the difference from 230 to 320 is the 320 is done completely on the highway at a steady speed less than 80mph from the beginning of the tank to the end.
is looking for his torque
Joined: Sep 2008
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I didn't notice any drop in MPG and I did the same thing about 2 months ago.
I normally fill up when the light comes on and thats around 310-320 miles on the tank. usually use about 12.5 to 13 gallons to get that. I know I could get another 30 to 40 miles once the light comes on.
I normally fill up when the light comes on and thats around 310-320 miles on the tank. usually use about 12.5 to 13 gallons to get that. I know I could get another 30 to 40 miles once the light comes on.
u get like 23 24 mpg huh?
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newbtacular newbness
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Joined: Jun 2009
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From: Seattle, WA
Some people have suggested checking the cat. I've been searching around on how to check the catalytic converter to see if it's been clogged. But there doesn't seem to be a DIY for it. Anyone know?
Just typed one up earlier this morning:
https://www.rx8club.com/showpost.php...9&postcount=55
https://www.rx8club.com/showpost.php...9&postcount=55
There might be, there might not. Cats have several different ways they can fail. Some of those are quite noticable and apparent, some aren't.
If you are out driving, and pull over and look under your car, if you see the cat glowing red, it's definitely toast. Severe cases of this will also have smoke from melting / burning shielding and plastic nearby, this smoke can also appear to come from the engine bay, since smoke rises, and once it rises into the transmission tunnel, the only way to go up is forward into the engine bay, unless you have enough air flow to push it out the back. Your center console rearward of the shifter could also get very hot. Not just the ~85f degree temps that are normally there, but like 150+
If your car feels like it is choking to death, and the harder you push it, the worse it feels, the more power you lose, you might have a cat failure the same as mine that I posted on the previous page, where it was basically becoming a complete blockage of the cat, and the exhaust couldn't escape, and wasn't getting clear of the rotor housing, causing a mess of issues.
I did get misfires from my cat failure. AFTER my brand new coil replacement, plug replacement, air filter replacement, e-shaft sensor reset, and MAF cleaning. I suspect that this was because the oxygen content was so low that it had trouble firing correctly.
You can also remove your cat and take a look inside. There are 2 honeycombs, and you should only be able to see one, relatively close to the header side of the cat. The pic I posted shows the 2nd honeycomb, with the sensor tube just before it. The chunks are from the first honeycomb that fragmented. Rapping on your cat might also allow you to hear rattling of chunks, if this happened.
Cat failure symptoms share alot in common with coil failure, plug failure, and engine failure. Figuring out which one is the challenge, although coil failure can lead to plug failure which can lead to cat failure, which at the extreme, can lead to engine failure. So it's always possibly E) All of the above.
If you are out driving, and pull over and look under your car, if you see the cat glowing red, it's definitely toast. Severe cases of this will also have smoke from melting / burning shielding and plastic nearby, this smoke can also appear to come from the engine bay, since smoke rises, and once it rises into the transmission tunnel, the only way to go up is forward into the engine bay, unless you have enough air flow to push it out the back. Your center console rearward of the shifter could also get very hot. Not just the ~85f degree temps that are normally there, but like 150+
If your car feels like it is choking to death, and the harder you push it, the worse it feels, the more power you lose, you might have a cat failure the same as mine that I posted on the previous page, where it was basically becoming a complete blockage of the cat, and the exhaust couldn't escape, and wasn't getting clear of the rotor housing, causing a mess of issues.
I did get misfires from my cat failure. AFTER my brand new coil replacement, plug replacement, air filter replacement, e-shaft sensor reset, and MAF cleaning. I suspect that this was because the oxygen content was so low that it had trouble firing correctly.
You can also remove your cat and take a look inside. There are 2 honeycombs, and you should only be able to see one, relatively close to the header side of the cat. The pic I posted shows the 2nd honeycomb, with the sensor tube just before it. The chunks are from the first honeycomb that fragmented. Rapping on your cat might also allow you to hear rattling of chunks, if this happened.
Cat failure symptoms share alot in common with coil failure, plug failure, and engine failure. Figuring out which one is the challenge, although coil failure can lead to plug failure which can lead to cat failure, which at the extreme, can lead to engine failure. So it's always possibly E) All of the above.
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