Brillo & RG NA Interceptor Testing
 

Well, after a full day of playing / tuning, I have a whole new level of respect for people who do ECU tuning for a living, this isn’t easy. RG and I are still getting our arms around the software, now that I found a serial to USB adapter that works. Here is the summary of my thoughts thus far with Scott’s base NA set of maps:

Software:

The current MT software is well featured, just not as intuitive as I would like. Saving and loading programs took a little figuring out. I wish there was a way to do negative split for fun, maybe a later software update will help.

Idle:

Starting the car is not an issue, although it doesn’t start quite as strongly as the car did stock. We need to play with this, see if it needs more / less fuel.

I have to give Mazda credit for getting our cars to idle as well as they do given how lean the stock car runs, getting the car to idle smoothly requires a seriously rich mixture (like 11’s). Now I understand that historically, rotary’s liked to idle at ~12.5 or so, so we’ll aim for that tomorrow, we played with the idle AFR and ignition timing with some luck, but we need more time to find a nice balance between smoothness and economy.

Power:

Scott’s base maps feel good under load, the car gets leaner with rpm for once, the throttle response feels better to me than stock. Cruising and acceleration feel good, no real hesitation or dead spots. We did notice that the tach needle would drop to 0 and bounce back once in a while, seemed to happen mostly over bumps, but it had no effect on the car, maybe the interceptor is interfering? We need to work on this one.

The car is at least as fast as stock and I’m sure it pulls harder in the upper rev band. The dips that I would feel as the variable intake system kicked in feel smoother.

I have leaned out the cruise map a bit, and I’m going to lean it out to about 15.3 – 15.5 for hwy cruising.

Other Issues:

The A/C seems to give the idle hell, which I know is just something we need to dial in more as the A/C puts load on the engine. I did notice the A/C seems to cycle more? This may have nothing to do with the ECU (I can’t think why it would), I’m going to have that checked out.

Check Engine Light – guess what, I’m running rich at idle  not sure if I’ll have to live with this or not.

Tomorrow we’ll try to dial the car in more now that we understand the systems.

I wish it did a few more things than it does. It only allows you to adjust leading/trailing split from 0-15 degrees. I was hoping for a much wider range as I am going to try some unorthodox stuff. Now I'll be severly limited.

I can't figure out how to get idle timing below 5 degrees. I'm not sure that it can go below this. I'll need to talk to Scott about this.

As far as the idle goes, the split and where you have the timing really doesn't have much effect until you get up over about 15 degrees of advance. Yes at idle. Playing with this seems like a fairly futile effort but I do have something to try yet.

As far as a/f ratio at idle goes you have 2 choices. Run it rich and get a nice smooth idle. You'll also smell it. Your other option is to run it leaner at idle, lose the smell, but also lose all the smoothness of the richer settings. Brillo is pretty anal. I'm not sure we can give him all that he wants which is an engine that barely sips on gas, is glass smooth, and smells like a bed of roses out the exhaust. ;) Somewhere it's going to have to be a compromise.

Much more playing to do yet. I'm much more accustomed to the Megasquirt and feel it's software is much more user friendly but in time this too will become second nature. It's just different. Stay tuned...

:mdrmed: :mdrmed: :mdrmed:

brillo,

what exhaust are you running from manafold back?????

beers :beer:

Stock.

i'm going to get a high flow cat at some point, hopefully before i kill the stock one :)

Yeah... LoL That might be a good idea.

if you had a choice, which one would you buy RG?

as i said before that map was made fore a 3" midpipe with a resonator... that is why it is off for you....

scott went under the assumption that most running the cepterx would have a midpipe or high flow cat....

i tend to agree with what he did..... scotts recomendation to me on a hi flow cat was the

http://rx7.com/store/rx8/rx8exhaust.html#supercat

beers :beer:

Fred,
Since this unit is totally programmable, there's relaly no reason that you shouldn't be able to get exactly what you want. The only problem is you may have to send the unit back to Scott or someone at microtech to reflash it to allow more customization of the timings.

There's no reason that this piggy back shouldn't do what you want. It's probably setup the way it is for safety of the common user.

there is a software update coming, and if we can show that negative split has some real tangible benifits, Scott will work with Microtech to make the hardware and software work.

Worse case, we can just flip the plug wires , but we need to get a better feel for unit first before we go their with my car.

Negative split is just something that few people know about since it was only implimented in a production car with the RX8 at idle. They don't use it anywhere else. I bet this has to do with emissions issue for some reason. Mazda must have tried it and found they couldn't make it work for some reason, but power doesn't appear to be the problem.

neg split is making the trailing plugs fire first right?

yup.

Brillo,
it shouldn't require any hardware changes to make it happen. It's all just the way the unit performs signalling.

The problem is that Alan wants the engine to idle lean and smooth. You have 2 choices, rich and smooth, or lean and rough. You can't have both. It doesn't want to run that way. When it idles smooth, he isn't happy about the a/f ratio being so rich. If it's nice and lean, then the idle isn't smooth enough. Please understand that his idea of a smooth idle is FAR smoother than my idea of a smooth one. Imagine trying to get an engine to run so smoothly that if you could place it on the surface of a body of water that it would not emit any ripples on the water. Glass smooth. You can't do this running it lean at idle. If it so much as makes a little hiccup jump for just a split second, it's too rough. This is a physics problem, not a tuning one. You can compromise of course and have it slightly lean and not quite as smooth but then you have neither thing that you want and it would have just been better to put up with one or the other. We've still got some things to try but realistically I don't see it happening to the extent that is desired.

rg,
quick thread interupt... for premix what do you recomend????? my pm has been unanswered for weeks...

fred if you what to play with the mid pipe that the testing was done with it is sitting in my garage... doubt if scott cares if you use it for a while....

and pm me for some info. i have learned a lot about exhausts in the last 2 days.... more power less money...

beers :beer:

Swoope,

RG says any good two stroke will work, its all designed to burn. I used the redline synthetic when at the track, it was good stuff

wow,
were you on vaudville i did not even see his lips move! thx, pm me for exhaust info...

but i think you are tuned into that, but i just figured some stuff out... that is not obvious..

beers :beer:

Gotcha, I do see the conundrum here. Like anything else, there have to be sacrifices made.. It's too bad we can't make it idle as if the engine were totally off (like an electric motor), now that would be something!

I think a rougher idle with an occasional pop and stumble is kinda cool, in that Harley kind of way :). It gives your idle some character :cool:

He was on the phone with me at the time.

There is the possibility that an upgraded ignition system could allow a smoother idle with a leaner mixture but that isn't something that has been done on his car. Maybe in the future.

today i drove for about a couple of hours without the ac.....

the idle is smooth.... my car has 47k miles on it...

turn on the ac... yes you get that ugly vibration when the compressor hits...

beers :beer:

is there something in particular that you are mentioning?

He is refering to the ignition coils, which in our car are kinda weak compared to the other RX7's.

Maniac (Jeff) upgraded his ignition with the AEM system (custom work) and was pleased with the results on his turbo car.

Currently, there are no drop in replacement coils, which would be nice.

so would there be any benefit to a car remaining n/a?