natuning

I have a bad catalytic converter 02 sensor currently.
Which means I have a few options:
1. I can replace it with the original Mazda sensor.
2. I can replace my cat with a midpipe

I'm leaning towards option two.
However, I do not want a Check Engine Light showing up everywhere I drive.
Is there a way to trick the ECU into thinking that my O2 sensor is just fine and get rid of the Check Engine Light using the Cobb AP tuner?
If so, could somebody explain to me how?

I also could purchase an overpriced BHR midpipe which supposively registers the catalytic converter as operating correctly.

I have an 04 California registered RX8, almost completely stock. If that helps anybody out.

Thank you very much,
Jesse.

TeamRX8

iTrader: (25)

if it's the front O2 sensor it should be rplaced immediately regardless of anything else you should decide to do

natuning

I am currently not in the states right now. I am deployed overseas with the Marines, so I really don't have access to my car until early 2011. But, my father told me that the mechanic said it was a "bad o2 sensor" which isn't very specific. what is the difference between the front and rear 02 sensors, as in far as how the ECU responds to them?

I know the inputs of air flow determine how my engine will run via the ECU.

Some other problems I've noticed with my car is that it has a terribly low idle where the car actually starts shaking, and it has decreased gas mileage from an average of 18mpg to 16mpg.

Could a bad 02 sensor be the cause for all of these problems?

I know the shaking from a low idle could be a loose motor mount.
It's pretty aggrivating not being able to put it up on a lift and look at it myself.

Currently, my father is taking care of the vehicle

Thank you again for any input on these issues.

RIWWP

iTrader: (2)

The front O2 sensor is what the ECU uses to determine the current Air/Fuel ratio, and adjusts the fuel flow to try to stay optimum.

The rear O2 sensor is just emissions related, to determine if the exhaust is being cleaned enough.

From your description it sounds like the front O2 sensor is the one that the mechanic is saying is bad. (wrong AFRs can easily = drop in gas mileage. Of course, a lot of other items can too...)


If you got the COBB AP from MM, it will block the emissions CEL from ever appearing. If you got it from elsewhere, then it might not automatically, but it certainly could be made to do so (though I don't know how).

If you are at all worried about emissions, and being a CA car there is certainly a valid reason for it, then just replace the sensor and keep the cat on.

wcs

iTrader: (2)

The RX8 uses both a MAF based system (your air input mentioned above) and a closed based system (Closed Loop).
Closed loop doesn't actually measure the incoming air but uses the O2 sensor in the exhaust system to asses the quality of the exhaust gases leaving the engine. The O2 sensor determines how much oxygen remains in the spent gases and feeds this information back to the ECU.

The RX8 has two sensors in the exhaust system .. The first one (and the hardest/most costly/most important) is the front O2 sensor,
The other O2 sensor is referred to the rear O2 sensor and is located in the Catalytic converter .... from all that I know ... all it does is measure the catalytic efficiency.

You need to determine which O2 sensor has failed ... I've had to replace my rear O2 sensor ... its simple simple to do.

Not likely
- Common items for this are, coils, plugs, dirty MAF, low compression, motor mounts

wcs

iTrader: (2)

Damn you RIWWP
You beat me to the punch

RIWWP

iTrader: (2)

Yours had a bit more clarity

wcs

iTrader: (2)

^ Thanks

I would like to add that the code registered by the ECU for a failed O2 sensor should indicate if its the front or the rear, should it not RIWWP?

Here is a link to the most common cel codes

https://www.rx8club.com/series-i-tech-garage-22/rx-8-technical-info-cel-codes-pcm-pin-list-collision-guide-26291/

Have a look around the P0138 or P2270
I think it was one of those cels I kept getting, I replaced my Rear O2 and bammm Bob's ur Uncle, cel never came back.

RIWWP

iTrader: (2)

Agreed, if there is a code, then it will tell front or rear. They can fail without a code though, so I guess it depends on how the OP's mechanic diagnosed it.

natuning

It is a the rear 02 sensor. I'm not sure how important this is to the way the ECU interprets the data, however, I do plan on getting a Cobb AP Tuner ASAP. I want to be able to lean out my car during the week, and then enrichen it with the octane it loves for the weekend canyon carving adventures.

RIWWP

iTrader: (2)

Rear O2 is only needed for emissions purposes.

wcs

iTrader: (2)

The rear O2 sensor only monitors catalytic efficiency .... it does not effect the cars closed loop parameters.

If you are not going to put on a cat-delete midpipe just make sure your OEM catalytic isn't clogged. The OEM catalytic's have a tendency to fail.

Now about the Cobb AP
1) You realize they stopped producing the Cobb AP, yes?
2) I don't believe people have found that the car is more fuel efficient on the Economy Tune (I didn't)
3) The Stage 1 tune provided by Cobb isn't really very good, most people get the serviced provided by Mazda Maniac
4) The Cobb will not enrichen anything with Octane .... this is strictly based on the fuel ... I'm not actually sure what you mean ... I'm guessing you want to run the cheap regular fuel during the week and the Premium fuel on the weekends? The Cobb AP on its own isn't really set up for this .... however using the ATR (Access Tuner Race) from Cobb you could build custom tunes for this, I suppose.

natuning

I will probably end up replacing the cat.
I didn't know they stopped producing the Cobb AP
I was talking about changing the air/fuel mixtures, leaning out the car during the weekdays with 91 octane, then adding an octane booster and making the car run rich on the weekends for more power gains.

I read about EMS, I thought the Cobb AP tuner was one.
Am I wrong? Please correct me if I am.

RIWWP

iTrader: (2)

The AP was discontinued, then BHR assisted in negociating a re-opening of it with COBB, with the AP for the RX-8 now sold exclusively through Mazdamaniac. There is no other source possible, but yes, it is available again.


Edit:
And your plans there really aren't solid. The RX-8 runs rich to begin with. Removing the cat allows you to run leaner (higher EGTs), but you also get more power from it. The generally most fuel efficient tune also pretty much happens to be the most powerful.

You can fine tune insanely close to get slightly better efficiency out of it, but you won't even be changing your mileage by a full single MPG. Maybe tenths of a MPG. It's not worth the trouble. Just get the tune optimum and stick with it.

wcs

iTrader: (2)

+1 on what RIWWP said ....

I have a question for you RIWWP: I knew Cobb was selling the AP for the RX8 exclusively through MM, however my impression was it would be only the remaining stock, are they actually producing more?

I see EMS and to me that means Engine Management System.
So moving forward on that level, the Cobb AP is not an EMS it is a reflasher.

What the Cobb AP will do:
1) Monitor most systems that are available via the ODBII connection, like, AFR, Engine Temp, Mass Air Flow, MAF Voltage, Ignition Timing, etc

2) Provides a way to reflash the ecu with new engine maps

Its does not provide you with a way to create your own, nor does it replace your OEM EMS.

However all is not lost. Cobb also makes available to the public the Access Tuner Race (ATR) software. This application allows you to create your own maps for tuning, which can be loaded in to the Cobb AP then you can flash your ecu.

natuning

Well, if the difference in efficiency and power are that slim, I'll go with power. I will definitely stick to running with octane boosters only on the weekend though.

I'm also going to be changing from 5W-20 during the winter to 5W-30 during the summer. (I'm from southern california)

I'm only 21 years old. And, I've got a pretty limited amount of money to spend on the car. It's pretty much completely stock, minus EBC brake rotors and pads, and the K&N panel filter I put in it.

I bought the car for 10 grand with 50k miles on it. The rotors were warped, which is why I have new ones on. It's a Grand Touring Package (6spd, leather) in brilliant black. It's got a few paint issues, some waterspots on the top, and some chips in the hood. It also has a few scrapes on the wheels. It's a 2004, too.

I have 2000 dollars to spend on it. What would you guys do to improve the performance? I've been looking at a Cobb Ap tuner, BHR midpipe, BHR ignition, new wheels, stereo system that lets me plug in my ipod, etc..
Obviously, I can only choose a few.

Thanks for any input,
Jesse

Kane

iTrader: (1)

Why would you run octane booster in an NA? Save that cash for HPDE.

The rest of your mod list looks fine...

natuning

HDPE? You mean take the car on the track?

I'm not so sure about putting it on the track just yet.
It needs more work done before I can feel comfortable putting it on the track.
But this is my only car and I wouldn't take a chance like that.
A split second and I could make a pretty big mistake, my father was a drag racer himself using the later model trans-ams. I've learned from his mistakes, instead of mine. I just want a car that sounds good, runs good and will last me another 5-10 years.

When I get adventurous, I just go dirtbiking.

RIWWP

iTrader: (2)

That was the case originally, since MM purchased a bunch extra. Then they got haggling, and the end result is that COBB will still produce the hardware for MM, with the basic RX-8 stuff on it, and ship it to MM, and MM will do all the stuff he does custom to the RX-8 flashes before initial shipment, etc...


The hardware is identical between all the different APs out there. Just the software differences. Which is what made them discontinuing it so hard to understand. It isn't like it's a matter of the costs not justifying it, since all the development costs are overwith and there is not a lingering cost for the 8's that they have to maintain a certain sales level to offset.



As in the octane boosters you buy from an auto-parts store? You realize that a full bottle of that increases by hundreths of an octane? One magazine did tests several years ago and found that the most concentrated version brought the octane rating of a tank of gas up by 0.11 or so. As in, if you put it in a tank of 87, you will end up with 87.11. Just buy 91 in the first place, it's cheaper per gallon than those boosters. You can't get "more power" from octane. Only reason to go with a higher octane is to reduce the risk of detonation, and 91 is already MORE than sufficient with N/A.

There are several big threads on octane, and what it does that you should read up on. This one is a sticky: https://www.rx8club.com/series-i-tech-garage-22/octane-what-actually-means-does-190858/

Save your money.

AP, BHR Ignition hands down for about $1,000. Get your 8 running where it should at least. After that it is certainly more opinion based on benefits and such.

natuning

What are the general horsepower/torque gains for the AP and ignition?

I've seen an average of 180whp and 130wtq for stock for the Rx8's.
Will those two upgrades get me close to 200whp and 140wtq?

I always run 91 octane and royal purple in my car.

I just thought 91 was pretty low, in other states you can get 93 or 95 pump.

REDRX3RX8

93 oct is normally found near coastal regions like Dallas, San Antonio, and Houston, for elevations under 1000ft.

In higher elevations 91 or even 90 is normal.

Every 1000 ft increase in elevation, can use one OCTANE less, and not knock because of less manifold vacuum.

wcs

iTrader: (2)

Only if you are lucky

RIWWP

iTrader: (2)

The AP can give you increases of ~2-3whp to ~10whp. Depending on how bad your tune currently is.

The BHR ignition probably gives a power increase, but since BHR refuses to market it as a power modification, the amount of gain is just guesses. This is also based on how bad your ignition is at the time you install the kit. You will get more gain by restoring lost power from a failing ignition than you will from one that is brand new.

Other than the AP, the only other 'easy' power gain is removing the cat and going with a midpipe. Combined with the AP, you can expect to sit about 190whp, assuming everything else is healthy. The power gain for your dollar spent starts dropping even faster after this.