shadycrew31

iTrader: (6)

The rear 02 sensor measures heat, its a glorified dummy sensor and most of us run without one.

abelavin7

Thanks RIWWP this was really helpful!!

abelavin7

Really? That doesn't affect your fuel millage? Or your emission test??

girth

iTrader: (1)

If your cat is replaced within the 8yr/80,000 warranty under the federal emissions standard, is the new one under the same warranty or perhaps an extended version?

Though I'm outside of my initial "first 8yr/80,000 miles", the cat on my car was replaced ~5 years ago and has taken a dump recently. I'm assuming I'm up **** creek, but I thought I'd check with others who may have had a similar situation.

wcs

iTrader: (2)

Strictly speaking of the Series I ... no ... the Rear O2 is only used to measure catalytic efficiency and played no role in fuel parameters.

HOWEVER ... just recently a forum member Oltmann has been reverse engineering the Series I ECU using some fancy hex editor software. Now he thinks the Rear O2 may play a role in fueling.

So the story is still out.

I'm not positive but I'm 99% sure ... I'll see you up **** creek. I'm the one with the Cold MGD
I'll have one waiting for you.

girth

iTrader: (1)

I figured, but I didn't want to dismiss the idea until I knew for sure. Just bought the car a few weeks ago and nothing but issues since

I hope you have a case waiting for me :]

Javii

iTrader: (1)

What could be the reason for the starter to kick in about a second after the key is turned?
No issues to start at all, it just seems as if there was a delay from the time I turn the key until I hear the starter running.
I actually hear the clicking sound when I turn the key, but the starter *starts* 1 second later. Also only happens when cold.

Wolfe

iTrader: (1)

What RPMs/MPH give you the best fuel economy? I am not 100% what the best speeds to shift into each gear are. I know its good to get it over 7k RPM at least once after the engine is warmed up, but what about the rest of the time. commuting on local roads for best fuel efficiency? How many miles have you gotten to a tank (city?) Thanks.

ganseg

iTrader: (5)

For me it was more important to take care of the engine than to get extra fuel economy. I wouldn't cruise less than 3000 rpm.

SamPappas

iTrader: (1)

Is there anybody that is running 5w-30 that can give me some straight forward answers. I have tried searching but everyone is aware that there is 10,000 threads concerning MPG with different oils. My rx8 is a 2005 with just over 60,000 miles and I just changed my coils, plugs, and plug wires less than 300 miles ago with a sea foam engine cleaning and I run 5w-30 oil. Should I honestly expect anything more than 10mpg? Also, I do not treat every drive like a time trial, but I get in a red-line every couple days.

DarkBrew

The "redline a day" story is too simplistic.

Get out and drive the car hard on back roads or on the highway. This is not a commuter car!
Avoid summer stop-and-go at any cost as over temp and low OMP flow will decrease compression seal life.
Avoid long stretches of cruising at steady low RPM as carbon build-up and low OMP flow will decrease compression seal life. A few redlines will not clear this out.

I get decent mileage at 130Km/hr and great mileage at 105km/hr (best ever was 9.9 l/100km)
Best mileage is always achieved with longer trips and fewer cold starts.

I have an oil temperature gauge and try to keep the oil between 80 C and 100 C... plus oil pressure mod on series 1 engines to ensure good flow at low temp.
Cobb AP is an awesome tool for data collection, fan turn-on temperature, OMP flow and various tuning applications.

I've run 5W20 and 5W30 Castrol GTX for almost all 137,000km

RIWWP

iTrader: (2)

There is no straightforward answer about oil because everyone has a different opinion. For a straightforward answer to exist it means that you would have to listen to 1 person as the expert to the exclusion of everyone else.

The oil you run will swing you your mpg by maybe 1mpg. Maybe. If you are getting only 10mpg then you have something quite seriously wrong.

Since you already addressed your ignition and decarb, work on the rest of this list:
My money would be on a cat failure.

DarkBrew

+1
sounds right... easy to test by borrowing a mid pipe and driving around a bit... Maybe you can tell just by looking at the mesh in the cat

SamPappas, what mileage were you getting before the plug/wire/coil change?

SamPappas

iTrader: (1)

thanks for everyone's opinions! My mileage has been a little better since I changed the plugs/coils/wires but not good. I guess I've never really paid attention to how bad it was, but I have been getting around 10-12 mpg for some time now. And to those who commented how to drive, I know how to drive my car, I don't drive for any stretch under 3000 RPM's and redline it more than enough to clear out the carbon. What I do know however is that whenever I ran 5w20 which was in the last fall when I bought the car it got like 17-20mpg give or take a couple. I've been running the w30 for like 9000 miles or so, and I have never had a straight forward answer as to what kind of city mileage I should be getting. This 10ish mpg is entirely city, I think it could also be because of the heat, it has been consistently over 105 for a while now. I am fairly sure my car is "healthy", it had plugs/coils/wires at 30k and 60k, plus the recent engine cleaning, I couldn't imagine having a bad cat at 61k miles on a properly driven and maintained car.

RIWWP

iTrader: (2)

There are quite a few assumptions there that COULD be true, but assuming that they are true can leave you in quite a bit of trouble.

For example, our cats usually fail between 60k and 80k. Why? Because heat and fuel kill cats. Heat burns them out, fuel saturates them out, both at the same time is basically creating a blow torch inside your cat. Piston engine cats last much longer because they run more efficiently (less fuel) and don't generate as much heat (they generate ~800F to ~1,000F, our rotary generates ~1,400F to 2,000F). You can tune for leaner combustion to get rid of the fuel, and spike your cat tempts through the roof. Or you can tune for more fuel to cool the exhaust temps down, but then you are killing it from flooding. The OEM tune is about the best of a bad set of possibilities.

If you add in ANY ignition failure, no matter how small, a flood event, or even a seafoaming, and your cat life drops dramatically. A failed ignition coil, wire, or plug can kill a healthy cat in very very short order.

kjb

Browsing around, I'm getting the impression that the RX-8 engine can be more prone to failure than the RX-7 variations, especially the FB and FC. I had an '86 RX-7 and now have an '07 RX-8. So far, my personal experience has been the same...one issue with each car and not engine related. With the RX-7, it was the second gear synchro and with my 8, it was a coil.

I'm thinking about buying an RX-7...maybe an FB, as an addition and not a replacement for my 8. It seems like all of them have well over 100k miles and the original engine.

My question is this: is there are difference in their durability and if so, why?

RIWWP

iTrader: (2)

It gets down to what fails on each, and why.

The main driving difference is that the FB, FC, and FE have increased the amount of power that the NA engine could deliver from one to the next. At the same time, Mazda has reduced the capacity of the cooling system, increased the complexity of the supporting components, and made more "consumer convenience" compromises. It's not really a recipe for success in longevity.

If you were to drop the power of a Renesis to FB or NA FC power levels, then it would probably last 150k+, simply because it would remove pretty much each heat related failure method.

The Renesis is arguably more reliable than the FD's 13b-REW, but then we have lower power and less complexity than the FD. Add a turbo to an RX-8 and the weaknesses of the Renesis are magnified dramatically, even more so than Mazda's factory addition of turbos to the FD.

wcs

iTrader: (2)

^^^ This plus

I've been on nitrous since 27k km's and boost since 60k km's
My engine is just getting ready to turn over 90k

Personally the I think the rensis is a rock solid motor

JPotta

Started and running now. Made the four hour trip to USAIR drifted fine all day and made it back home. Still having some hot start issues and breaking up on the top end slightly. CEL is saying Manifold Absolute Pressure Low Voltage.

cuttincorners

I just ordered the cobb ap and read all jeffs instructions but im not sure of the 1st thing i should do...
should i send him my invoice to start the process?
i added him as a friend,
reading his directions i feel like hes the soup natzi on sienfeld.
if i mess it up im screwed right,?

someone just tell me in english real simple ,
talk to me like im a 2 yearold,

cuttincorners

Maybe your starter is getting weak
maybe your oil is still thick cause its cold
or your batery is diening

RX8Soldier

iTrader: (24)

Do you have the Cobb AP in your possession?
If yes, then watch this video

Javii

iTrader: (1)

I was thinking starter too, but its weird that once it engages it starts right up

ormisnash1

i just had a greddy turbo kit installed on my rx8 it runs perfect except when at a dead stop. The car idles at 500rpm is there a way to increase the rpm so i don't stall? I have to keep my foot on the gas and idle at 1000. I did do a cobb access port and am waiting to here back from jeff. This will be the fourth tune with him is that something you fix with the access port

RX8Soldier

iTrader: (24)

could be a number of possibilities. Who installed the turbo? Are there any modifications to the kit? Everything hooked up properly?