Ok, did this with my LM1 wideband setup today.

You'll see a double spike at shift and idle, which is a bit odd.

http://www.swankmonkey.com/images/af_log1.jpg

there's a few other ones, but this is the trend with the double spike.

Also at cruise it's reporting about .80 on the freeway.

The new rpm sensors from http://www.innovatemotorsports.com/products.php (LM1) are about ready, and I'm going to be beta testing one very soon! Then I can map a/f with rpm, and most likely get the box soon where I can tap in my egt and other engine sensors ;)

that would imply that it drinks A LOT of gas while idling doesn't it.

especially when the engine is cold and it's the first start of the day and you're warming it up. that needle seems to go down a notch right there.

Originally posted by energie
that would imply that it drinks A LOT of gas while idling doesn't it.

Hi energie,

It actually looks like the renesis is running at a 22:1 a/f ratio (or higher). This would be very lean and would imply that it drinks very little gas at idle.

The lean idle mixture also helps heat up the cats faster.

Brian

Originally posted by syntrix
Ok, did this with my LM1 wideband setup today.

You'll see a double spike at shift and idle, which is a bit odd.

http://www.swankmonkey.com/images/af_log1.jpg

there's a few other ones, but this is the trend with the double spike.

Also at cruise it's reporting about .80 on the freeway.

The new rpm sensors from http://www.innovatemotorsports.com/products.php (LM1) are about ready, and I'm going to be beta testing one very soon! Then I can map a/f with rpm, and most likely get the box soon where I can tap in my egt and other engine sensors ;)

Hi Syntrix,

Great work so far! I was wondering how lean the renesis was running at idle. It looks like just over 22:1.

We also see ratios of about 18:1 early in first gear. It will be very interesting to see more of your results as they are available.

Brian

That makes some sence when you think about it. Passing CA emissions was a large hurdle for Mazda to jump. How do you get cats to work at thier peak?...they need to be hot. That's whare the gas money goes.

First of all the engine is warmed up. Who implied that it was cold?

A lot of engines will go lean when off throttle.

My concern is the overly rich while on the throttle. That is where some tuning can be done.

The 1st gear 18:1 is just starting, not WOT.

I guess I need the rpm box to show you all where things are happening. I'm glad there is interest in tuning on this board, but it appears that a lot of people are definately new to this.

I'm one of the ones that wants to learn about it but has no experience whatsoever. I'm pretty good with electronics and computers though so I might be able to learn something eventually :D

/me is confused.

/me scratches head while looking at squiggly lines.

/me understands ratios

/me is waiting for an explanation of readings

Hi Syntrix,

What is the lambda when the car is started cold?

It was assumed that the lean mixtures in 1st were not at WOT as it has already been determined that the open loop mixtures have been very rich.

Brian

It starts part throttle in 1st, then get's wot. If you are looking for wot readings, look at the 2nd gear run.

WOT is indeed what others are calling "pig rich"

If that was WOT, then a 11 or 12:1 really isn't that pig rich, optimal I think is somewhere around 13-14:1 right? I remember seeing dynos that indicated around 9 i thought, now that is pig rich.

... maybe this really shows that the ecu is indeed richening the mixture when it detects that is on a dyno.

9's would be double pig rich.

In these graphs there is a LOT of room for improvement, IMHO.

Here's another one from today after work.

I still need to log when cold, but I'm not going to go WOT when the car is cold ;)

http://rx8.swankmonkey.com/images/af_log2.jpg

edit: That run is 2nd to 9.5k rpm AND 3rd to 9.5k, corrected text in graph.

And here's a 1-2-3 gear run getting on the freeway today:

http://rx8.swankmonkey.com/images/af_log3.jpg

On a side note, http://www.innovatemotorsports.com has been a great company to work with! They have a few new products coming out soon. I did all of this with their LM1 unit, which has a separate wideband O2 sensor that must be welded in before the cat.

They are sending me a beta inductive pickup overnight.... it will be here tomorrow.

With this, I can show RPM with the A/F, AND I should be able to tap in my EGT probe (already welded in), as well as a few of the other engine sensors.

I hope to get a tps value, as well as a few other things into the logging very soon. This weekend should be fun!!!!

I hope these graphs help you all out.

For those that are newbies to all of this, try to google for some of the terms. I could try to explain it all, but I'd be typing all day long ;)

Idle values.

They are usually right at stoich. It's the letting off the throttle that causes the lean spikes.

I do have a very long graph of my freeway run home today, but it's waaaaaaayyyyyy to long to try to post! Here's just a sample of it:

http://rx8.swankmonkey.com/images/af_log4.jpg

Originally posted by syntrix
[B
You'll see a double spike at shift and idle, which is a bit odd.

[/B]

I must be reading it wrong -- it took over 1 sec to shift from 1st to 2nd? No, that can't be right :D

Will be nice to see it with RPM and EGT also. Thanks!

That's about correct, WOT, but smooth slow shifting.

I could slam gears, but I'm not on a racetrack!

Beta Box is here!

Should get some good data tonight or tomorrow!

Good stuff. Seems to corroborate everyon'e suspicions on the ECU tuning/running rich issue. Will definitely stayed tuned to this one...

Hi all,
I just discovered this thread. I have been curious about the remapping of the ecu and the air fuel ratio. I have done some approximate calculations and using xylene as the model compound, I calculate an air/fuel ratio of 13.7 at complete combustion with no excess oxygen. The units are pounds of air per pounds of fuel. Are these the correct units?
The heat capacity of gasses is very small compared to that of liquids or solids. This means that it would take a huge volume of hot exhaust gas to heat the catalyst up to working temperature. Therefore, it would seem to make sense to ”slip” a little extra fuel to the catalytic converter to get it up to temperature and have the heat of combustion warm the catalyst. I suspect that the reported Air to fuel ratios are not based on measured pounds of air fed to the motor divided by pounds of gasoline fed during the same period, but by some gas composition. It is conceivable that the combustion is not the same everywhere in the combustion chamber. Therefore, measurement of per cent of only one of the combustion products could lead to problems interpreting the data. Does the RX-8 run extra rich at idle and start-up? Is this the cause of the low gas mileage? What in fact is actually measured?
Hope these are not too many questions, but I am still learning.
Thanks,
Ron

Originally posted by Ron
Hi all,[..]
Does the RX-8 run extra rich at idle and start-up?
[..]
Thanks,
Ron


I'm not soo smart on these issues, but that's the one thing I hope to have grasped correctly so far. Extra rich at start-up.

-Peter

Awesome information, syntrix! What I'd really like to see would be a graph showing the AFR mapping at different revs - run it at 1,000, 1,500, 2000 on up for periods of time and see how the AFR varies over the rev range. This would confirm canzoomer's observations. I trust his comments about lean and rich ranges in the stock ECU map but I'm a visual kind of guy, I want to see the graph.

Keep up the good work!

Originally posted by ptiemann
I'm not soo smart on these issues, but that's the one thing I hope to have grasped correctly so far. Extra rich at start-up.

-Peter

Actually, from re-reading some of the early posts, it looks like the opposite is true -- VERY LEAN at idle (22:1 a/f ratio...). But I'm also a noob at this game, so I could be wrong...

That's letting off the gas. Check my other post here where I have rpm AND a/f.