The last couple weeks my mileage went from around 17 to around 14-15. I'm running the AC constantly and it's been pretty hot here so that could be it. I've also been driving a little faster on the highway, averaging 75. That explains the low mpg, I Think.

However, I also had a temporary problem with the clutch and wonder if it might be related. I went to drive one day and the friction point in the clutch had moved to the absolute bottom, and the top portion of the travel felt like nothing was there, almost like the clutch cable slipped. I didn't like it so I parked... but then it started acting normally and has ever since.

Any ideas? I will be taking it to the dealer for oil change this week so what should they check?

 

First, the RX-8 doesn't have a clutch cable.
The clutch is completely pneumatic. It does have a clutch hose, but that won't slip.

The friction point on the RX-8 is adjustable, and hopefully not, but it's possible that the adjustment screws are loose, which I doubt. More likely though, you're experiencing clutch bracket failure. There's a metal bracket that holds the clutch pedal assembly in place that wears out over time. Mine went at 82,000 miles or so. It'll eventually snap and the piston for the clutch cylinder will likely come out of alignment completely.

If you're in warranty, mazda will replace it free (8 year 96k covers it).

As far as your gas mileage is concerned, even in texas, in the hottest weather, I got better gas mileage than that. How many miles on your car? When was the last time your plugs and coils were changed? Notice any loss in power?

Fouled plugs or failing coils will definitely hinder your gas mileage. So will a clogged cat or loss of compression.

One other thing to note, on the series one, the secondary injectors kick in at 3750 RPM. In 6th gear, the maximum speed you can go w/o using the secondaries is 72-73mph. If you've started cruising around at 75, you'll get worse gas mileage, but I doubt that much worse.

 

This car is a 2006 Shinka with 42k miles, and the last 2400 miles on a new engine. I know about the clutch assembly but didn't know about the bracket, I'll have that checked carefully. There's no loss of power. The only other thing I can think of is I've had two occasions lately where the traction control kicked in with wet tires, but that's normal I think.

 

Yea, DSC kicking in during wet conditions is really normal.

42k miles is a bit low for the clutch pedal bracket, but not impossible. The telltale sign is squeaking when you depress the pedal. Mine had it only very briefly, then it stopped and about 5k miles later the pedal bracket snapped.

 

It is not pneumatic, it is a hydraulic system.

 

Jasmine you did not fully answer Ajax questions…How many miles do your plugs, coils, and wires have? How is your CAT doing? OEM ignition components last for about 30,000 miles...

I would also inspect the MAF...

 

Because I don't know. The cat was replaced with the engine but I don't know what else. I find out where it was done though and they have the records I just need to pick that up. I plan to upgrade the ignition either way.

 

It is always a good idea to update your ignition if you are unsure of how many miles the current components have. That should help with your mpg, engine and CAT life. It is also a good idea like I mentioned earlier to clean your MAF. It is super easy! Here is a DIY: https://www.rx8club.com/series-i-do-...an-maf-113167/

 

Yeah that's a hell of a good suggestion. Here in Arizona, it's stupid dusty and we had a little dust storm earlier this year. I replaced the filters after that but didn't check the MAF, it's probably dusty as heck.

I don't know if this link will work, but I was thinking I would pick up these...

http://www.partswebsite.com/mazmart/...20081&fl_id=41

But... isn't there a better coil than that one? Or is that the good one? I got parts from Mazmart for my RX-7 before and they treated me right so I like them, but if I can get a better part somewhere else, that would, well... obviously be better

Like this... I'll consider this... Black Halo Racing Ignition System | Black Halo Racing

 

Yes, you are correct.
Air vs fluid, but either way not cable driven.

 

I buy most of the parts from Mazmart as well. Never been disappointed. However, the BHR ignition kit is a great upgrade. A lot of people in this forum are using the kit and love it. It is bit more expensive but the kit's life is a lot longer than the stock coils.

Since you are planning on cleaning the MAF, go ahead and clean the ESS as well (you can just use a dump towel and swipe the sensor; no need to uninstall anything). Here is a bit more info: https://www.rx8club.com/series-i-tec...eaning-206687/

 

OK yeah... there was a K&N air filter in there, but it was beyond cleaning. I put a paper one in there and we'll see how that goes. Clutch was a little bit weird again today, so I'll get her over to the dealer on Monday. I had a long trip this weekend, looks like I'm taking the Honda

 

The Mazda dealer says everything is fine, no errors reported. So, I guess the mileage is just from the heat. They checked the coils and it's fine too.

 

IMHO...

Coils. Even if oem style. You might be surprised....

 

The dealer checked the coils and they are fine, but yeah I will be getting the BHR ones anyway. Can't hurt, right?

 

Update: the actual clutchplate is worn. The bracket and everything is fine. I'll need a new clutch soon. Mileage issues seem to be just the heat and my driving style. We do a lot of cruising at 45 mph around here, and I was doing that in 4th gear, now doing that in 5th. Nothing is wrong with the engine though, that was my main concern.