Tirewarmer

The car:

96 with swapped in 99 Engine
99 intake manifold with VICS
RB Header, cat eliminated, cat back RB exhaust
Monsterflow intake
Timing at ~14 degrees(where it made the most power on the dyno)
Stock 96 ECU
Due to class limitations using stock 96 Injectors, fuel pressure regulator, fuel pump. These cannot be changed.

The problem:

Put the car on the Dyno and was pretty happy with the numbers of 130whp/112ft/lbs, but it ran lean just about everywhere. A/F was was above 15 at 4000 rpms and was 14.2+ from 5200 rpms on up. There should be some power to be found with more fuel.

Goals:

1. Fix the lean situation: Per class rules, I can chip or flash the ECU, or run a piggyback that control fuel only. I have not seen much on flashing/chipping the 96/97 OBDII ECU, so I assume that a piggyback would make sense in this situation. I have looked at the APEXIs, Emanage Blue and Ultimate, and AEM F/IC, but haven't had any experience with any of them. Looking for advice on which one would fit this application best, works best, is reasonable easy to use, as well as possibly being able to offer a solution to the next two goals.

2. Eliminate the stock MAF: Initially, I had wanted to go with a megasquirt PnP, and eliminate the factory MAF and go with an IAT, since the research that I have done shows that it may be a significant restriction in the intake tract. Since this is no longer an option due to the limitations of my class, is there a piggyback that would allow me to eliminated the factory MAF and do something similar to what Joe Perez did when he eliminated his AFM?

3. Run a second tune with ignition/timing control: I run additional events that are not constrained by the same ruleset. I could control timing via a piggyback or flash/chip at these events. Is there a piggyback, chip/flash that would allow me to control fuel along with timing, but allow me to disable the timing portion either via an alternate map or disconnecting a harness, wiring etc?

Savington

iTrader: (31)

What class? If you are referring to STS2, you can build an MS that fits inside the stock case.

Tirewarmer

Nope. I wish it was that easy. NASA TTE. And I am out of points. A SAFC/VAFC is free, as well chips, flashes, daughterboards, etc. I have to maintain everything going through the stock ECU.

Joe Perez

iTrader: (8)

Copied from my reply to your same post at Miata.net:

For #1, this is one of the few times that I'd actually recommend a PowerCard, namely the TC2. It's the lest expensive device I can think of for the job, and adding tiny amounts of fuel is exactly what it's for.

Considering #2 and #3 as well, an EMU would seem like a good fit for your needs. By following what I did on the 1.6, you can create a MAF-substitution table which will allow you to eliminate that device and run MAP-only. The procedure would be precisely the same as the one I outlined- running and logging on the stock MAF for a while to generate the data, then running in MAP mode with the MAF still in place to compare the two and fine-tune your map, and then finally removal of the stock sensor.

As to ignition, you could simply connectorize the two ignition wires (brown and brown/yellow) such that they can be connected to either the EMU or the factory ECU.

Savington

iTrader: (31)

Lame. For an NA application, something like an SAFC might be the best bet. I think even an EMB controls spark as well, and I know the AEM F/IC does. Can you run those boxes, but not wire them into the ignition circuits and have them be legal?

I just totaled up my NASA TT points a couple days ago - 82 points on top of my re-classed base class.

Tirewarmer

Yes, lame I know. That is what I was thinking. I can run those type of boxes and just not use the ignition cicuits. I really want to do it right the first time, so if there is an option with a good interface, 16x16 fuel table, or other big positives, I would rather buy once and have something good, reliable, functional etc.


Yep. Aero absolutely kills you for points with NASA. Myself and another car both broke the existing TTE record at Carolina Motorsports Park this weekend. My car has no aero at all. It just isn't worth the points. I'd love to have a big rear wing and a big front spoiler splitter.

Tirewarmer

Thanks Joe, I read the response there also. Running the two ignition wires so that they can be disconnected is a good idea that I hadn't thought of.

I am basically looking for 9-10 more whp as it is all that I can have and stay within the weight to WHP limit(16.5 to 1) of my NASA class.

What would the upside be of the Emanage Ultimate over the Emanage Blue?

What do you both think about the Apexi SAFC-II or the Neo?

I don't want to spend a ton of money, so a $200-$300 option would be great, but if i need to go more expensive for added features, realiability, etc. I'll do so.

I am 2 tenths of a second off the track record right now, and the track record holder and I alternated taking first place this weekend for each day. I can easily take off the 40 extra pounds that were on the car to make minimum weight for the next event, and would love to have a few extra ponies to put me over the top with the competition as close as it is right now.

Stephanie Turner

Does the piggy back have to be INSIDE the ECU housing? I ask because the MSM one has to be.
Stephanie

Tirewarmer

The piggyback does not need to be inside of the ECU housing.

Tirewarmer

These are the rules that apply to ECU's and piggybacks:

This would cost me points:
12) Aftermarket computer system (any non-OEM “stand-alone” or “piggyback”):
+3 naturally aspirated, +10 forced induction

These are free

49) OEM ECU/PCM reprogramming or chip (must use OEM ECU/PCM box/housing/hardware)
50) Programmable fuel systems without control of engine timing (such as SAFC, VAFC)
51) Non- OEM sensors or alteration of sensor inputs (such as non-programmable MAF or MAP
voltage “clamps”)

Technical Bulletin (2-10-09):

Replacement of the OEM '90-'93, '95 (with VIN's higher than 14193), '96-'97, and '99-'00 Mazda Miata ECU 4.0MHz "clock" crystal, and the OEM '94 and '95 (with VIN's lower than 14193) Mazda Miata ECU 8.0MHz "clock" crystal with an aftermarket crystal of different frequency, sometimes referred to as "overclocking" of the ECU, is permitted as a no-points modification.

Technical Bulletin (4-20-09):

All vehicles (rule wording addition):
No-Points Modifications section

49) OEM ECU/PCM reprogramming via reflashing or replacement/aftermarket ROM chips or simple ROM boards (The OEM ECU/PCM box/housing and hardware must be used).

Prior wording:
49) OEM ECU/PCM reprogramming or chip (must use OEM ECU/PCM box/housing/hardware)

Joe Perez

iTrader: (8)

For your purposes, the EMU would enable you to remove the MAF sensor, whereas the EMB does not have this capability.

I'm not a huge fan of devices that work solely by manipulating the airflow signal. For one, it's a less precise means of controlling fuel, and for two, altering the airflow signal alters the load computation, which affects not only fuel, but ignition as well- specifically, an increase in load causes an increase in fuel and a decrease in ignition timing. A small difference, to be sure, but why move in the wrong direction if you don't have to?

As I said earlier, the Powercard TC2 (aka Powercard Blue) is really the only fuel-only controller that I'd consider in your application, as it alters fuel not by tweaking the MAF signal, but by directly adding duration to the injector pulses after they leave the ECU. And at $170, it's also considerably cheaper than the Apexi devices.

Tirewarmer

I read through the Powercard literature, and this seems like a great option that I would have never thought of.

I have an Innovative wideband O2 with gauge sitting on the shelf that I need to install. From the Powercard instructions, it looks like I will be able to tune in real time using the wideband O2 to get my green, yellow, and red settings on the Powercard pretty close, then be able to hit the Dyno and make sure that everything is where I thought it was.

Can anyone give me a good link to A/F ratio tuning, either general or specifically for a Miata? I know the basics, but it looks like I will be able to do some major fine tuning with the Powercard as far as A/F ratio goes, so a reference of what the best targets for A/F based on load, RPM etc. would be great.

Thanks again guys and I'll update here with my old and new Dyno charts once I get the Powercard installed.

Joe

Joe Perez

iTrader: (8)

I wouldn't do much work in the low-load areas, as I doubt you spend much time there at the track.

In general, peak torque is usually thought to be achieved somewhere in the general neighborhood of 11.5:1 to 13:1, thought of course you'll need a load-bearing dyno to find the sweet spot for your car.

As to timing, do the rules state the base timing must be set as per manufacturer's recommendation? Assuming you are running high octane fuel (better than 85 R+M/2) you can probably turn the CAS ahead a bit to increase the overall timing by several degrees. Again, you'd need a dyno to find the real sweet spot here, but this would seem to be an allowable modification.

If I were feeling particularly creative, I might interpret the new wording of 49 (specifically "The OEM ECU/PCM box/housing and hardware must be used") to permit the installation of a MegaSquirt into the OEM ECU housing, using the OEM hardware to mount and connect to it.

Tirewarmer

That gives me a decent start as to where to tune on the street. Since the powercard should let me tune in real time under load at full throttle on the street with a codriver/tuner person to adjust the settings, I should be able to get pretty close before I hit the dyno again to fine tune. With how lean that I am currently running, I'd have to assume that if I get the A/F between 12 and 13 under load at full throttle, I'll be making more power than the current 14.2 and up that I am seeing.

I can set the base timing however I like. I did this on the dyno by moving up the timing until power peaked and then dropped again, moving the timing back to where power was the highest.

Great minds think alike. I already told the head of NASA TT that my interpretation of this rule was that, "you could do anything inside of the box, including a standalone." His response was basically, "I wouldn't do that."

JasonC SBB

Just an FYI of the AEM F/IC's capabilities:

It can shorten or lengthen injector on-times - it has intercept wire pairs for each injector. The injector table is a 3D table with RPM and MAP as the axes.

It can retard ignition timing. This table too is a 3D table with RPM and Load as the axes. Load can be spec'd as MAP or MAF voltage. Because you have a CAS, you can advance your CAS to advance some portions of your effective timing table and then use the FIC to retard from there.

AFM signal can be modified, based on a 3D table. The load axis can be spec'd as MAP or MAF voltage (independent of load for ignition table).

It can also synthesize O2 sensor signals and override it under certain conditions.

The AFM signal can also be synthesized ("MAF elimination"). My only beef with this function is that there is no IAT correction. Joe, any comments on MAF elimination in general without IAT correction?

Given the rules, if diddling the timing is not allowed, you can achieve your target timing by synthesizing the MAF signal (MAF changes timing), and then correct the fuel error with the injector corrections.

Joe Perez

iTrader: (8)

I've never done it myself with a MAF sensor, only VAF.

The EMU did not permit any temperature-based compensation of the synthetic airflow signal either, and yet the correlation between synthesized and actual signal did not seem to change appreciably with temperature, at least not within the boundaries of temperature that one typically experiences in San Diego in January. I'd expect that, of course, given that for a certain volume of air per unit time (as measured by the VAF sensor), mass will increase as temperature decreases, assuming a constant pressure. The same phenomenon should work just the same for a MAP-based system, where for a given manifold pressure, mass per unit time should increase as temperature decreases, assuming a constant VE through the engine. It all works in practice because the ECU is compensating density-for-temperature after the fact. Ergo: parity.

With a MAF sensor, one should, in theory, experience a discrepancy between actual and synthesized MAF voltage as a function of temperature. For an ideal MAF sensor (one which is internally compensated), output voltage would remain the same for a given mass of air per unit time, regardless of the air's temperature or pressure. What I honestly don't know is whether the MAF sensor used on the Miata is internally temperature compensated for density, or merely as a scalar to account for increased wire current as a function of ambient temperature. (A given mass of air at 0°F will cool the wire inside the sensor by a greater amount than the same mass of air at 100°F, thus, sensor current must be corrected against ambient temperature.)

It's certainly worth investigating. It may turn out that the discrepancy, if any, is too small to be of concern. If the discrepancy is nontrivial, does the AEM have the ability to do temperature-based fuel trim? IOW, compensate for it after the ECU on the injector lines, rather than before the ECU on the airflow signal. On the EMU, you were able to have two fuel correction tables going at the same time- the first was typically MAP-based enrichment, while the second might well have been used for temperature-based compensation.


As a matter of practicality, it should be noted that the MAF sensor in a '94+ car is not nearly as restrictive as the VAF sensor in an earlier car. I do not expect a naturally aspirated engine with a stock head to benefit significantly from its removal.

JasonC SBB

Nope.

M-Tuned

iTrader: (6)

Why not build a fuel only Megasquirt?

Tirewarmer

I hadn't thought of this. Let me propose it to the guy that makes the rules.

For clarification, a fuel only megasquirt would take care of the fueling on its own, with no afm signals going to the stock ECU, and no fuel injector control coming from the ECU?

Has anyone done this before? And could someone build one for me since I don't have the ability to do it on my own?

Joe Perez

iTrader: (8)

Hmmm.. I'd consider it in violation of rule #12, and yet permitted by Rule #50. Definitely worth investigating.



That is partially correct.

The injectors would be disconnected from the stock ECU and connected only to the MegaSquirt. The CAS signals would be split and fed to both devices. The MegaSquirt does not require a MAF signal. The wideband O2 sensor would be connected only to the MegaSquirt, with the stock narrowband sensors left in place feeding the stock ECU.

The MAF signal would still need to go to the stock ECU in order for it to control the ignition timing. As I said before however, I don't consider the 1.8 MAF to be a significant restriction on an otherwise stock engine.



Dozens, if not hundreds. In the early days, the MegaSquirt was a fuel-only device (hence the name) intended simply as a replacement for carburetors on vehicles using a distributor and conventional non-computerized ignition. It was't until the Squirt-n-Spark code was created that it became a practical ignition controller.



This sounds like a good cause, and an interesting challenge. I'd be happy to turn one out for you in exchange for beer.