Hey guys, I have been readings posts on the forum for a while, and learned a great deal about my 8, so thank you all first.

Now I really need some advice. I have a 2007 RX-8 GT 6MT with 66000mi, absolutely love the car. But here comes the frustrated part.

When I first bought it, I was getting 9 mpg city 15 mpg hwy, and I thought it was because I haven't been driving a manual for a while. But after 3 months and taking the car to the dealership for diagnosis 3 times (cost me about $600), no results. Fuel injectors checked, O2 sensors cleaned, MAF cleaned, and no CEL at all. The only mods I have are K&N Typhoon Intake and BHR ignition system & new plugs (just put it on 2 weekes ago). Plus the ECU was reflashed the last time I took it to the dealership. Right now I am getting about 12mpg city 18mpg hwy (#93 gas), and I am driving like a granny.

Recently I occasionally smell burned gas/exhaust from my vent, so I took the car in the Mazda dealership, and ask them to check the CAT. They said nothing wrong with the CAT visually, but the smell was from the melted heat shield on top of the CAT (I was charged 350 for that.) and they tell me they can't do nothing about the low MPG if there is no CEL on. So I EXPLICITLY ask for compression test and a full test on the CAT (Since both the CAT and Engine are still under warranty if I remember it right?), then they said they couldn't do it without giving me any reason. I mean, the people there are nice, but what they are telling me right now is we can't solve your problem right now, which really frustrates me.

So what do you guys think I should do now? Again, I know the 8 is definitely not a gas saver, but I just want to at least have a average mpg that most members have.

Thank you for all of yours time!

Btw. I live in Lancaster, PA area, is anyone from around here who knows reliable
mechanics messing with rotaries?

Steve Z

 

18 mpg is about average.

 

Get some PB Blaster and a socket wrench and check out your cat for yourself.

 

Tell them you test drove a friend's RX-8 who just recently had a remanufactured motor installed, and you realized that your car is way down in power in comparison to his/her car.

That should then get you a compression test.

Also, you should find a different Mazda dealer, as that one probably isn't going to do anything on your behalf anyway.

BC.

 

Sorry for being dumb....although I read a lot threads, I have no idea how to actually examine it...so what should I look for when loosen it up???

 

I've heard the same story w/mine. Reason is techs can't take a **** wo/Mazda tech line's sayso. I went in with no power, couldn't get past 65mph in any gear, told them it was the cat. Asked would they please check the cat - "No." Why? "Can't, no CEL, tech line won't authorize visual inspection."

After a long time and way too much stupidity wo/effect directed by the MNA tech line... and getting no where, the lead rotary tech took it upon himself to convince MNAO that it was a possibility. They finally agreed and ... Surprise! Cat was plugged. That took nearly three weeks.....

My advice, pay the cost to the dealer to unhook the three bolts at the exhaust manifold and calmly ask them to "DROP & LOOK IN THE FREAKING CAT!!" Can't be much. What do you have to lose?

 

Thank you for being so helpful BC unfortunately they are the only Mazda dealer that is close to me. Do dealers avoid replacing parts that are under warranty because they bear the costs?

 

Wow I will probably just ask them to do that when I pick up my car tomorrow. Btw I have been getting a problem like when i am driving in a parking lot in first gear at 8 mph if i slightly tap the gas paddle then I get hesitations with no cel on or flashing so I thought the rpm was too low but the weird part is this almost never happens if I'm in second gear...again I don't know much about cars except addicted to watching Top Gear so please forgive me if this is dumb ....😁

 

How are you calculating your gas mileage?

 

well I'm having the same problem also I was getting like 10/22 city/highway gas mileage when I first got the car driving pretty slow (i know for some reason my high way mileage is really high) and it died one day got a new engine went back up to 17/23 city/highway driving little aggressively because i heard "Rx8's are meant to be driven hard" but after like a year my mileage came down to 13/23 again(i know still really good high way mileage...) driving exactly the same so I changed my whole ignition system(coils/wires/plugs) and i heard my rear o2 sensor was bad so I changed that costing me nearly 2 grand all together. still 13/23.... tried cleaning MAF, don't have the knowledge to clean SSV so my next step will be switching all the filters (I have AEM CAI) and maybe seafoam or Mazda ZOOM cleaner thing.

but seems like 13-14 city gas mileage is pretty normal around many rx8 owners except the lucky ones so I'm not complaining much.... I always red lined pretty much everytime i drove and I still do. But I'm happy that I still get REALLY high highway gas mileage.. I've gotten 32x miles off of one tank and it was 13.3 ish gallon fill up ending up being 24 miles to gallon on cruise control.

I think i might even try getting ECU reprogrammed but not sure what to do yet don't feel like spending more and more money.

let me know if you find out anything!

 

Charles, thats good info. I'm glad that you would back up your product like that, and it gives me that piece of mind if I ever have an issue at a dealer.

 

I really appreciate your willing to help Charles, and needless to say the new ignition system really do make the output more smooth especially at higher RPMs. So thank you and BHR. One thing I want to point out is, the dealer found out the heat shield that is used to fend off heat from CAT is burned, and I just realized isn't it a good indication that the CAT is overheated and is failing????

 

A burned heat shield is an indication of a restricted overheating cat.
Look under your car one evening after a nice drive down the freeway. See if the cat is glowing red.