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Extremely low milage on my rx8

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Old 10-10-2010, 07:10 PM
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Extremely low milage on my rx8

hi,

I am getting really low km/tank for my car and i have no idea why. first off i live in Vancouver, BC so that may contribute to it but not by this much. I get 280km per tank driving my rx8. i have been looking around and cannot figure out why it is so low. i drive mostly city and i own a 2004 rx8 GT. i usually say at 60km/h most of the time. any ideas?
Old 10-10-2010, 07:34 PM
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how do your wires, plugs and coils look? ever been changed. You would be surprised what a healthy ignition system can do for your mileage
Old 10-10-2010, 07:48 PM
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^ that and is you Coolant light on? I know that the ECT sensor fails which will cause low mpg
Old 10-10-2010, 09:08 PM
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280km per tank is very vague.
gas millage?
Old 10-10-2010, 09:55 PM
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seems fairly normal to me for city driving
Old 10-10-2010, 10:41 PM
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280 km is way too low for a full tank unless u r on redline every trip. Check ur ignition system as suggested. Check ur catalytic converter while u r at it, clean ur maf sensor and throttle body too and seafoam if u must.
Old 10-10-2010, 11:00 PM
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Like Jason said, "per tank" is too vague to figure anything from. I usually fill up at around 170 to 180 miles, which is close to 280 km, but my mileage is fine.

Souhjah - how about dividing miles (or km) by gallons (or litres) on your next three tanks, then come back here with some numbers?

Ken
Old 10-11-2010, 01:11 AM
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lol sorry about the km things, im in vancouver and we use km alot so yea....
i am not too sure how to check those things.
the only thing i know is that, to clean the maf sensor you spray it with something special.
other than that i dont know how to check my cat, throttle body, and ignition system. what is seafoam? im terribly sorry for my lack of knowledge but im a quick learner. i will forsure do some research in the morning but as of now, i am too full of turkey and drowsy to do it. =)
Old 10-11-2010, 01:32 AM
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1. It would also be helpful if you could tell us more about the maintenance history of your car such as are the coils, plugs unchanged since you have the car?

2. When cleaning the MAF sensor using electronic cleaner, try not to spray any on the o-ring and reinstall carefully to make sure you don't pinch it. The o-ring tears easily.

3. You can check the cat by visual but that requires jacking up the car, another symptom is engine power loss (does not rev freely at high rpm)

4. You have to remove the accordion tube after the MAF sensor to access the throttle body, you can clean it the same with electronic cleaner or if you wanna be thorough, you remove the whole throttle body so you can clean behind it as well

5. Seafoam is a bit more involving, check out the DIY for that.

6. Have a mpg log, its useful to tell if anything is amiss with the car.
Old 10-11-2010, 01:40 AM
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www.fuelly.com track it for at least 5 tanks then come talk to us.
Old 10-11-2010, 02:59 AM
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Alright I'll do that.
Old 10-11-2010, 10:24 AM
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Originally Posted by lilring
^ that and is you Coolant light on? I know that the ECT sensor fails which will cause low mpg
How does the sensor affect mpg? I ask because mine has been on for a long time, but if I really think about it, my mpg may have been only mildly affected.
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Last edited by dmorales; 09-09-2011 at 04:02 AM.
Old 10-11-2010, 10:37 AM
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Where do you usually keep your rpms at when you drive?
Old 10-11-2010, 11:26 AM
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The coolant level sensor has nothing to do with the ECT sensor failing

If your coolant temp sensor fails..and the car thinks it's cold all the time..your mileage will suck..and the car will run really rich

The CEL should be on if it fails completely......
Old 10-11-2010, 11:27 AM
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ugh my coolant sensor has been unplugged for years. No problems here.
Old 10-11-2010, 02:19 PM
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i usually shift at 4000 rpm. if i were to visually check my cat, what am i looking for?
Old 10-11-2010, 02:26 PM
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280km to miles is about 175...

thats what us city guys get.. i wouldn't complain.
Old 10-11-2010, 02:30 PM
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I generally get to 200 before I i have to fill up *around 15mpg*

Your mileage doesn't seem too far off.
Old 10-11-2010, 02:33 PM
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Originally Posted by RWD+LSD=Zoom
ugh my coolant sensor has been unplugged for years. No problems here.

Coolant sensor or coolant tank level sensor ?
Old 10-11-2010, 02:40 PM
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Visually
the CAT will change in color and you would look for loose or damaged wires. Drive it around till its fully warm and look below the car and see if the CAT is glowing. Also to get a real good idea, you would have to take it apart from the exhaust sytem to look inside to see if its plugged up or breaking away.
Smell
•A foul smell is the most common sign of a bad catalytic converter. If you smell what seems to be a rotten egg and it gets stronger over time, the catalytic converter is not working properly.
Fuel Economy
•A large drop in your fuel economy may be a sign that your catalytic converter is going bad or is blocked.
Power
•A lack of power, especially at high speeds, may be a sign that the catalytic converter is going, or has gone, bad.
Idling
•A vehicle that stalls during idle, or idles rough, may have a blocked or bad catalytic converter.
Acceleration
•Your catalytic converter may be blocked if you experience bucking or hesitation while trying to accelerate. Additionally, your vehicle may run at a higher than normal temperature.


Read more: Signs of a Bad Catalytic Converter | eHow.com http://www.ehow.com/facts_4854981_si...#ixzz1253RKD3W
Old 10-11-2010, 02:41 PM
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Was you gas mileage better previously and suddenly got worse? Or has it always been like this? A lot depends on driving patterns, obviously, and these cars don't do well in stop-go boulevard traffic, but if it suddenly got worse, like people said, get the coils/plugs/cat checked out quickly. Losing one of those can create bigger problems if left untreated.

In the cat, you're looking if the honeycomb is plugged up or destroyed. Normally you get misfires and power loss if the cat is really dead, but you might be in the early stages. If you rarely exceed 60km/h, do you normally exercise the car? Rev it up to redline on a nice straight somewhere? That would be a good idea. (but not when it's sick)
Old 10-16-2010, 08:30 AM
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Hi all, just bought the '05 Grand Touring w/ 53k miles on it in perfect condition. Has some crazy after mkt air filter system which makes it super loud (kinda like that part) but the mpg is scary. Am below the "E" at 175m, sometimes 160! That's like 10mpg. WTH?!?!? Any suggestions??? Bought it after reading factory specs stating should be around 20 - 24. Thanks!!!!
Old 10-16-2010, 09:54 AM
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i get about 260 miles (418km) to a tank of gas. thats generally ~20mpg. but that is at least 75% highway driving.

in the city i get about 14mpg. which is about 168 miles (270km.)

to get 150km to a tank of gas.... i have to be on a track and flat out racing. that's actually right about what i get when racing. 8mpg. 96 miles (154km)

so.. are you going flat out and shifting at 9km rpm constantly?
Old 10-16-2010, 01:58 PM
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before i was getting more for sure someing like 300 and its was alot smoother the ride.

I took a look at my car and found that all, yes all, my coils had big burn markings, the size of your finger mails, on the bottom. i believe that that is a bad sign. so i ordered a new set

i was also wondering where is the location of the engine mounts? and what does it look like? pics?
Old 10-17-2010, 06:22 AM
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Dont be so lazy, get under and take a look. I am amazed at stupid questions.


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