I drive about 90/10 city/highway.

When I first got the car new, I would get about 375 km before the fuel light came on.

It's two years now, at 51,000km, I get about 275 km before the fuel light comes on.

Last month, I changed all my fluids and put fresh spark plugs in.

I did not change the stock coils or the plug wires. I don't have any misfires at high RPMS...

Could coils make that much of a difference? Or am I missing another maintenance item that contributes to fuel economy?

 

Air filter likely the most important.......

 

Coils !!! never mind the fact its getting cold and its generally accepted that rotary's use more fuel when its cold out isnt it?

Andrew i think I've said this a few times i'm not sure if your not reading my posts of waiting for someone with a little bit more credit than me to say this. I've replaced my coils twice and both times i noticed better fuel consumption and feeling a fair bit faster. i have never had a misfire at high rpm. i really don't think waiting for a misfire to replace coils is wise. i assure you your losing power without ever realizing it. i never thought i had been down on power and even running respectable times at the drag strip but soon as i replace the coils it felt quite a bit better.

 

Nate,

It's the first time I heard this from you... I'm not ignoring you.

As for air filter, I changed to the K&N Filter in March this year. Stock intake. I looked at the filter element, it doesn't look that dirty at all. It doesn't need to cleaned after just 7 months of usage?

 

For reference I'm getting around 340kms a tank (136,000kms), untested in cold weather yet. So age probably doesn't have all that much to do with it. I also notice I get about 20-40kms less using Shell V-Power than "run of the mill" 91 (odd, yes). Another, less significant note, I seem to frequent the gas stations more as I get closer to tune-up times.

Since you've replaced everything else that is logically a factor, I'm going with Nate and saying do the coils. You could also chop it up to a gradual change in driving style, possibly becoming more aggressive than when you first got the car?

My 2 cents.

 

Your lucky I replaced coils spark plugs and wires and all i get is 200 km to A FULL tank. 2005 with 48500 KM

 

now that's REALLY bad...is it driving style? or the engine oil and other fluids? I used to get low 200s when i first got the car, but after an engine oil change...transmission fluid change and a change of most of the other fluids and running on only V-power 91 i now get 340 per tank...that's before the cold is settling in. At best i've done 400km a tank when i did 50/50 hwy/city.

MrAdam5: that's really surprising since i get the COMPLETE opposite for my car. When i use V-power i can get between 340-380...depending on where i'm going (if i'm doing more hwy or more local). But when i use regular 91...i find that I'm getting 300 tops...maybe 320 if i'm lucky.

 

oh and these numbers are all when the gas light JUST comes on, so it doesn't include the 50ish km that we're supposed to be able to do after the gas light comes on...

 

I know, I don't quite understand it unless the station in town is messing with their gas... But I did regular 91 for a tank, just to and from work everyday and got around 340kms, then a tank of V-Power 91 and got just around 310kms doing the same thing. I'll probably run that again when there's a consistent temperature out and see what happens.

 

Gas mileage and car performance are inverse of one another by variably adjusting right foot value.

 

Yea, I've gotten as low as 190KM to a tank.. Depends.

I like to drive above 4K most of the time. I also burn excess fuel quite often. This is done by revving to 7k, and slowly removing your foot from the petal... POP!!! :D

There goes some gas

 

Foot, I'm exactly the same as you (no plugs yet), even after putting on a RB intake & duct my fuel economy did not go up (thought the RB would help). I'm going to try cleaning the MAF/IAT this week to see if that helps. In the spring I'm going to change out the plugs, wires and coils all at the same time, then ask the dealer to seaform the engine (get the carbon out). If after all this is done, and it does not work, I guess I'll just have to live with the poor fuel economy.

 

as always, nates right. i think its odd that you havent noticed him posting this everywhere. but anyways, i've got 107 000ish km on my car and i still get around 350/tank. that will definilty end in about a month when the temps drop and stay there...im not looking forward to that.

last winter, i changed my plugs before the cold came. i was getting just over 300/tank. then i started to notice alot of missfiring when i pushed the car if it was even a hair before fully warm and my mileage was rarely above 200/tank. as soon as it was fully hot then the missing would be gone and it would run fine. got new coils and bang. i've got highish mileage. i've got non synthetic 75w90 in both the diff and tranny and i always keep my oil fresh (ususally around 3000km).

you dont need to have missfires for the coils to be weak. also, you could have both or one trailing coil completely dead and still not have any missfires but your mileage would difinitly suffer. You could always go into scarb mazda and ask them to test the spark from each coil if you are curious. that would be cheaper than buying the 4 new coils, although the exchange rate is pretty much even right now. andrew, if you are going to order some coils from the states, let me know. i would like to get some spark plugs again before the winter. I'll give you money upfront if you will order them along with your stuff (if you decide you are going to do the coils).

good luck. try and get this sorted out before the winter. as im sure you know, our cars have to be in tip top shape to survive a winter without letting you down. battery has to be perfect. you need plenty of spark, and a clean air filter. you dont get away with anything. we've already started to see the first run of flooded rx8s now that its cooling down outside. all of them being higher mileage on original coils, plugs, wires. and they wont pay the money for new plugs (until the car is flooded and they have to).

 

Ok guys... thanks for your suggestions... I did clean the MAF sensor as well last month. The only thing left is..

1) change coils
2) clean K&N filter (but only after 7 months of usage)? Should I clean this still?


The parity of the dollar sounds good now to buy the RB spark wires and new coils. I know y'all gonna say "Footman should know better to use the search button", but can you guys cut me some slack and tell me where I should order the coils from cheap? finishline? fluidmotorsports? etc... etc...

I will also try really really hard to run one tank completely without passing 5k RPM to see if the effect of the right foot makes a difference, because it is true, I am vastly more improved and aggressive from when I first bought the car.

 

I got like around 350km per tank as well.... 2007 Rx-8 with 19,711km on engine.......

 

thanks andrew it just feels like iv posted in a 100 times and i know iv posted it in a few of your threads. anyways iv herd good things from finishline, im not a big fan of fluid for various reasons but i know many Canadian members have bought things throu him and been quite happy.

 

i got my coils from finishline last year. the problem though, is that they ship UPS and you can get hit pretty hard by their "brokerage" fee. It cost me 60 bucks on top of the coils and the taxes. still saved alot of money over buying them here. but if you could find another company that ships via USPS ive heard you can avoid alot of fees that way. I think marc (thumper) knows a good company.

as for the K&N cleaning. it definitly couldnt hurt although i wouldnt think its necessary. i put my K&N in over a year ago and i havent cleaned it yet. more than 30 000km on it. but like i said, it couldnt hurt as long as you do it right (with the K&N cleaning kit).

 

I say spring for the BHR coil kit and never worry about it again. OEM coils are weak sauce..

 

oh boy.. lets stop it here before we go ahead with the BHR vs. OEM coil debate.... stick to the original question guys...

Thanks...

Any other input? Before I buy coils, next tank, I'm going to drive around only using below 5000 rpm and see what happens...

 

I do

Hasn't the issue of 8's fuel economy been talked to death?!

^TheWulf...after all the research and cost for the BHR compared to OEM, personally don't think it's worth it, less u don't care about cash.

***edit** as footman said on topic! Please do not respond to my comment only IMO!

 

stay under 5000rpm? what i always think to myself if i'm going to drive the 8 like the focus why not take the focus and save half the gas.

last time i got coils was from Charles at bhr and i didnt have to pay anything other than the money i paypal'd to him forget who he sent it thru, just was so happy not to have to pay a singe dollar in taxes or fee's

 

welp... there's one other thing... general wear and tear of the car... over time it's going to have to work harder to get the same performance n all... going to burn more gas... not much that can be done about it. Everything else that you can do to bump it up has been discussed... really think that's about it.

as for the keep it under 5k thing... been there.. done that... got like an extra 25-50km out of the tank... but it was a complete PITA. It's by hard the hardest and most frustrating thing you can do in the car. Specially in traffic around Toronto.. where if you don't gun it at points, no one's ever going to let you merge.

 

now here's another question... how much does coils cost here?

and sticking to footman's question... i'd like to know too... thanks!

 

If you go to the dealer about three times the cost of online. Plugs also, I got a price of $285 at the dealer $80 online. Cheapest I've seen coils is $28 U.S. each, but I can't remember where.

But nows the time to buy with our dollar almost at par.

 

Then again im always heavy on the gas. you guys think its time for me to change my tranny fluid i got 48550 Kms. Just changed my oil at 46500