lolachampcar

The goal of this thread is to do a cooperative step by step nitrous set up on an 04 RX-8. With luck, we will end up at the +75 (or, dare I hope, +100) nitrous set up with the most reliability and least expense. We are aiming for less timing to allow for more nitrous.

We are off to an interesting start and I would like to post a problem/question for feedback. I have attached two data logs. The first is from a naturally aspirated 05 with a stock EG flash. The second is a 04 with nitrous installed but OFF. There should not be much difference between Air/Fuel ratios on a stock 04 and 05 RX-8 and yet the 04 with nitrous (again, it was off) is so rich that it has saturated the oxygen sensor.

My first guess would be that the fuel solenoid is passing fuel even when the system is off. Does anyone have an opinion? Calling Mr. Hill for help.......

jones75254

iTrader: (2)

In the example above my car is the nitrous equipped example. As far as mods my car has the RP Supercat and the greddy sp2 catback. Nitrous system is ZEX with a 55 shot. As of right now we (Bill) are trying to figure out why my AFR's are so saturated at full load in comparison to Naar's car. Again, similar runs were made with both cars and the nitrous was NOT armed during my run. Before i am to start tweaking timing for a larger shot based map i want to be sure my car is running as efficiently as possible with the existing map and it looks right now that it is not. Any thoughts as why my car is running so rich at full load? It seems that the AFR's are normal up to about 7k rpm, but form 7K and up they get saturated. I dont see any reason why my AFR's should be much diff than Naar's car as his is an 05 and mine an 04, both having the latest mazda flash, but it seems it is. Thoughts?

lolachampcar

The following became apparent on a different thread-

"The thought occurred to me (yeh, I know I am a bit slow) that the ProLogger software is available as a free download on the EFIDude site. With Naar's permission, I can just put the data file up on this thread so anyone interested can download it and take a look for themselves.

Any interest?"

Jones, may I post your data file here as well for others to view?

jones75254

iTrader: (2)

Yes thats fine Bill. I also exported you the data file i just went out and logged if you want to check that one out and use it.

lolachampcar

Ok, I asked the Dudes if their software could be downloaded by anyone and used to view data files. They weren't sure, gave it a try and said it should work just fine.

So, I've attached the Jones data shown above. Just place this data on your desktop then go to www.efidude.com and install ProLogger (you will find it under downloads and it is free). Do not bother with installing the drivers as they are only needed when you want to download data from a data logger.

Once installed, go to file - import and import the Jones data file from your desktop. You should now be able to "fly" all the data yourself.

There are two "pulls" towards the middle of the file. These are rips up to about 80 mph. I was told that the first rip was with nitrous OFF while the second was with nitrous ON.

Please let me know if the above install and view process is clear, if it works and if you have any problems.

jones75254

iTrader: (2)

Bill, i know you posted it on another thread in the EMS section but can you go ahead and attach Naarlevens data file as well so the people here can see what we are talking about with respect to the AFR difference and how mine are much richer? I know the still shots in the first post show it but this way people can scroll through the whole run and see the difference throughout the runs. It is this AFR difference that is believed to be reason for my MAF's being a bit lower than Naar's car (hence less power). I didnt reach high enough rpm's in my runs to compare exact Maximum data with Naar but if you look at my car at say 8k rpm and his at 8k rpm you will see the diff in MAF's.

lolachampcar

Here is Naar's data. There is a short street blast when he showed up at the dyno, the first stock N3Z2ET 04 flash based dyno pull, another dyno pull with just a tad of fuel removed above 5500 (reflash) and then a street rip after pulling it off the dyno. The different sessions are separated by vertical grey lines where time resets to zero. You can also see the download date and time if you hover over the data within ten seconds of the start of data. The EFIDudes added this so you could have logs spanning years to keep track of and compare data over long periods of time.

As for slight differences in MAF for the same operating point, that could all be down to air temperature. The cooler the air, the denser the air and the more you will pump through your engine. That being said, it was bloody hot on the dyno when we did Naar's pulls. Also, Naar is not running a cat.

I would start with the much bigger fish first and find out where all that fuel is coming from before worrying about small MAF differences. Just my two cents worth.

jones75254

iTrader: (2)

Ahhh yes, i forgot Naar was catless....explains the diff in MAF a bit more.

lolachampcar

Charles, do you think there is any merit in capping the nitrous fuel line before or after the sol and turning the bottle off before logging some more data? This would effectively put us back to a no nitrous starting point for doing that NA tune.

Did you get a chance to load the log viewer software and look at the data? The O2 sensor just slams to saturated under load for almost all of the non-nitrous pull. Do you think the nitrous may have nailed the sensor? It would not seem so to me given that the sensor seems to work just fine when the PCM is in closed loop but I have no experience with nitrous on sensors or failing RX-8 O2 sensors.

CnnmnSchnpps

iTrader: (1)

Jones do you have an intake on your car? Could be playing tricks with the MAF.

Other than that, check the performance of the fuel injectors?

--edit--

To the original point of this thread.. I am fairly confident you can run up to a 100 shot progressive without any tuning (starting around 55 shot and ramping up as the revs increase). I'm planning a setup to test this theory

lolachampcar

If you do not mind, please post the results here as well. By any chance can you also post some data logs?

CnnmnSchnpps

iTrader: (1)

I'll be showing the project every step of the way, don't you worry..

jones75254

iTrader: (2)

I have the stock intake with K&N drop in, so i dont believe that to be the culprit. I will be doing some testing tomorrow. Preliminary thinking is logged data shows my LTFT is pretty high (5.47-6.25 under load) and this may have something to do with the fuel saturation, i dont know, so...we'll see. I may also do the selenoid check as well just to be sure.

lolachampcar

I looks like we need to address a Long Term Fuel Trim issue before actually tuning for nitrous. I'm going to start a different thread on the subject so we can try and get feedback from a lot of different cars.

I have attached two screen shots of rips with an initial 5.5% positive LTFT and then after the LTFT was cleared (by pulling the magic fuse). There is a significant difference. I’ve also included a screen shot of the car building LTFT after the trims had been cleared. Lastly, the data file is attached as well for your viewing pleasure. Just go to www.efidude.com and download the ProLogger application (for free). Do not bother to install the drivers as you only need them when you want to download data from the logger. Once installed, go to file import car data and import the attached file (after you have unzipped it).

Thanks Jones for the data!!!!!

lolachampcar

The nice thing about the factory PCM is that it is so powerful and does so much so well. By the same token, it is a bit like an IPhone in that it does what it does well but do not expect it to do anything else.

I wish the factory PCM could control nitrous by hijacking an existing control feature or could be fooled into switching between maps by using an existing feature in a novel way but I doubt it. I think you are absolutely correct about that.

I do think PCM tuning can allow for two nitrous friendly changes-

First, we can pull timing out where the nitrous comes in. This new timing map would be there all the time so we will have to look into just what we loose by not having the timing in non-nitrous mode. We should also look at exhaust gas temperatures to make sure the timing change did not send them even higher.

Second, if we get the long term fuel trim under control, we can choose high load mixture targets that compliment nitrous. Again, we need to see how this impacts non nitrous performance but it is an option.

Lastly, we do have access to VDI and six port timing so that is a tuning option as well. It is a very long shot but, if we have the time and interest, it provides one more set of variables to try.

I am also very interested in seeing the logged data develop with these different approaches. The mixture data may help provide better jet tuning for the nitrous systems (or maybe not).

Can you think of anything else? I will scratch my head a bit and look at the load v rpm tables to see if there just might be a feature we could hijack but I would not hold my breath on that one.

lolachampcar

I think the best we can do for now is try nitrous friendly changes to the mapping and use only those that do not provide too much of a penalty when the nitrous is off.

Are you running it on a regular basis and, if so, can we get some data from your car as well?

lolachampcar

Me thinks someone is looking for more than 55......

CnnmnSchnpps

iTrader: (1)

We all are, it just takes time.. There are a couple of approaches for going above 55 shots but a direct port system is highly recommended..

lolachampcar

I just posted a note on the Open Source NA Tune thread (https://www.rx8club.com/showthread.p...81#post2335981) about the need to cal the MAF or custom fit a tune to the car. Should we just go ahead with the tune for this car then look into timing and such for adding more nitrous?

NaarLeven

pm'd bill

lolachampcar

File on the way to be edited.
Attached here for reference as well.

CnnmnSchnpps

iTrader: (1)

So, I tried putting my thoughts on nitrous tuning to paper (excel) tonight. A big difference between nitrous and supercharging is that instead of changing the density of the air entering the engine, it instead changes the chemical mixture of it (the mixture is technically no longer "air"). Why is this important?

Nitrous has a stoich AFR of 7:1 Therefore the stoich AFR of an air/nitrous mixture is a weighted average of 14.7 and 7 based on what fraction of power is coming from air and nitrous, respectively.

Now, for smaller shots the calibration of the jets takes care of the proper AFR, as has already been demonstrated. The issues start when you increase the shot. The percentage of power from nitrous increases, and the target AFR of the mixture decreases. Please see the attached spreadsheet for a stab at showing this and getting some approximate numbers

Also, another big concern is - just how "wide" do they make the wideband O2 sensors? Tuning for a 0.8 lambda, at 5000 RPM you end up with something like an 8.7:1 target AFR.. Do WBO2 sensors go that low?? If you want to fine tune the fuelling with an aftermarket EMS, you need to be able to tell what is going on for some range around your target AFR..

Anyway, please look through the spreadsheet and let me know what you all think.. Am I way off base or is the theory sound?

Thanks,
-Dmitri

CnnmnSchnpps

iTrader: (1)

On another note, I am getting closer to figuring out how to tune for nitrous properly. In this regards the EMU is superior to a reflasher since you can set it up to only pull timing / adjust fuel only when the nitrous system is active. I believe I can also use the EMU's extra injection channels to make it into a progressive nitrous controller..

CnnmnSchnpps

iTrader: (1)

Right. I believe the AP (at least in its previous incarnations) supported a "live map" feature where you could quickly load up a map without turning off the engine. That's still not quite like flipping a switch

If you can get an external box to handle timing the solutions would be very close to equivalent..

CnnmnSchnpps

iTrader: (1)

But the EMU is so much fun to set up :