Little black boxes. Little black boxes lying to each other and to the ECU, tricking the system into thinking everything's OK and you need a little less timing or a lot more fuel.
This approach of using piggyback computers to control air/fuel ratio, timing and boost has been the most oft-exercised when dealing with cars with seriously increased power output such as forced induction and nitrous oxide.
Black boxes do indeed work, but have limitations in terms of ease of use, tuning and the precision with which you can make adjustments. Re-chipped computers, which means your ECU gets its fuel and timing maps moved to a removable burned "performance" chip in a socketed orifice, has a serious price advantage but no user adjustability. Many of these chips are optimized for high-compression, quad-throttle body race engines and not for your average B16; they don't read the knock sensor and give you horrible gas mileage.
These methods of tuning are clumsy, inconsistent, and should really be used only when there's no other option. Stand-alone engine management such as MOTEC, DFI, HALTEC and the like offers extremely precise control, but with a price tag several times that of piggyback computers. The caveat? You better know what you are doing to a) see positive results and b) not blow up your engine. Stand-alone engine management, of course, can be used on any car, but re-wiring the engine compartment and tuning the engine from scratch is an intimidating prospect for most.
Even without extensive engine modifications, we wanted to see just how much power we could make with more precise control on our nearly stock engine. And with serious normally aspirated modifications, nitrous, forced induction and built engines on the horizon, it was time we figured something out for Project Civic. Of the three options listed above, a user-programmable system would give us the kind of flexibility and control we need with the variety of setups we have planned, but we wanted to keep it as simple and cost effective as possible.
The System
We found a happy compromise in the Hondata, a stock Honda ECU modified to provide custom tuning and special features from your stock box. The obvious advantage is you get to keep the stock wiring harness, and all the convenient stock features like maintaining idle with accessory loads and controlling the emissions subsystems. Moreover, the unit was built with ease of use in mind, and it costs less than most other stand-alone systems. Various stages with various price tags are available:
*Stage 2 - Full fueling and timing adjustment by any Hondata dealer or owner of a Stage 4 system
*Stage 3 - All Stage 2 features plus a two-stage rev limiter for drag launch and full throttle shifting.
*Stage 4 - All Stage 3 features plus HondaLogger, Hondata's real time datalogging software, and ROM Editor, the user-programmable management software.
*"b" for Boost - All the aforementioned stages can be bought with your ECU modified to work with up to 29 lbs. of boost. The Hondata is primarily designed to work with the ECUs from '92 to '95 Civics and '94 to '00 Integras, although some others will work:
*Hondata charges $125 to convert P74 and P75 (Integra LS/GS) computers to VTEC.
*P05 and P06 ('92-'95 Civic CX and DX) automatic or manual ECUs can be converted to VTEC.
*Prelude and Accord ECUs must be swapped with one of the above ECUs. They are a direct plug in.
*The Hondata system will work with JDM but not U.S.-market EF computers, e.g. the ECUs marked "PR3" or "PWR" that come with JDM B-series engines.
For EF chassis turbocharged applications, Hondata suggests you switch to an OBDI computer because this removes one of the two oxygen sensors on the earlier setup. Placed in incorrect positions in a turbo manifold, these oxygen sensors will not read each pair of cylinders properly and can cause the engines to run poorly or sustain damage.
Stage 3 and higher systems come with a launch control system that lets you set a special rev limiter that activates only when the car is stopped and the clutch is in. Set it at 2800 rpm, for example, and you simply mash the throttle, wait for the light to change and dump the clutch. This can be an excellent tool for bracket racing. The full-throttle shifting function (Stage 3 and higher) will drop engine rpm any specified amount during shifts, allowing your right foot to stay planted while you shift.
On turbocharged applications, this full throttle shifting allows less boost to be lost between shifts, which can be helpful with larger, laggy turbos. An interior-mounted push button is included, starting with Stage 3, which allows the user to adjust the launch limiter, VTEC changeover point, the full-throttle shift limiter, shift light and overall rev limiter, all without the need to open a laptop.
One benefit of using the stock Honda computer is the onboard diagnostics still work, offering 65 error codes on OBDI, or 92 with OBDII-equipped cars. This won't seem very exciting until you actually have to track down a problem. Even better, with the HondaLogger option, you can record all the stock sensors your ECU is reading. Depending on the laptop you connect to, the HondaLogger can sample from 75 to 500 readings per second, for up to six hours.
Hondata goes beyond the physical sensors like VTEC pressure, 02 and water temp to include calculated sensors such as revs and selected gear. Road racers can watch a lap-by-lap replay of their braking, find out how much throttle they're using, what gear they're in, the range of engine temperatures, etc. If you're more interested in engine performance, you can watch injector duty cycle, intake charge temperature, etc. during a run or just cruising around town. All of this, of course, assumes you're carrying a laptop in your car.
The electronic dash function provides real-time feedback from a variety of sensors, and with the HondaLogger installed, offers real-time playback of both the dash and all sensors. Hondata has done an excellent job with its electronic dash, which displays all important data in an intuitive, easy-to-read format. You can play back your logged data while viewing with either the digital dash or an X/Y graph of each selected sensor, both of which are easy to use. If you're mining data for on-track tuning, viewing the graph format is ideal. We'll be using the Hondata's logging capabilities in upcoming installments as another valuable evaluation tool.
Tuning it
With the engine in exactly the same state we left it in Part V--an AEM intake, PowerCore cat, and A'pexi WS exhaust on an otherwise stock, JDM B16A--we headed to our dyno with Doug Macmillan of Hondata and a new Hondata stage 4b ECU. We weren't expecting huge power gains on such a mildly tuned engine, but adding the Hondata now allows us to learn how to use the system with minimal risk to the engine. Making a novice mistake later, with lots of boost could be very expensive.
The Hondata Stage 4b comes pre-loaded with 12 maps, eight of them stock, for various B- and a D-series engines, and four modified programs for bolt-ons, cams, turbo and supercharged applications, to be used as starting points. It turns out we already had a program loaded that was optimized for a 2000 Si engine with bolt-ons similar to our own. Nonetheless, after time on the dyno with our new Dynojet wideband 02 sensor in place, we gained power everywhere. Most of this horsepower was gained smoothing out a rather rough air/fuel ratio, with a small portion of the gain attributable to a little finesse with the timing maps. These gains are clearly not shiver-me-timbers huge, but the engine was already strong, suggesting it was in a pretty good state of tune.
As the ECU is still a Honda unit, you simply plug it in like a stock one. The only difference is you need to make a slight notch in the case to make room for the wire that connects the Hondata ECU to the PC interface box, where you connect your PC via a common RS232 connector.
While tuning the Hondata, you remove the ECU's lid and place an emulator on top of a ZIF, or Zero Insertion Force socket. Once you have a program optimized, you burn a chip using the Pocket Programmer, install it, and replace the cover so it looks and functions like a stock ECU. Though this may sound like a drawn-out task, all tuning was done on the dyno, so we used the emulator for several hours of tuning and burned a chip once our program was finalized.
To use the emulator, once you have made a change to a map, you select "download current table," restart the car, and you're ready for the next run. The whole process is very intuitive, even for those a bit computer-phobic, and the provided instructions, which are also available on the web, are excellent.
Our Stage 4b comes with the Hondata ROM Editor 2.5, which provides the interface between the user and ECU. The Hondata interface programs are all designed to work with Windows operating systems. Those with Macs can run the system, albeit much more slowly, using a Windows emulator. All Hondata software is provided, free of charge, on its Web site.
When creating a new ROM, you select whether you're running normally aspirated or with forced induction, using either the stock MAP sensor, good for 11 psi of boost or a GM MAP sensor, good for 30. The system also accounts for injector sizing and any alterations to stock fuel pressure. While we tuned the car, we ran the car in open loop, turning off the 02 sensor, as this makes power runs more consistent with the ECU out of learning mode.
We waited until the water temperature reached 170 degrees F on the electronic dash because, under this temp, the computer is adding cold fuel enrichment.We waited until temperatures within the intake manifold were fairly consistent to help ensure the only variables involved were those we changed during testing. After a base dyno run showing power equal to what we measured in Part V, we plugged in the Dynojet wideband 02 sensor, which graphs the air/fuel ratio in addition to the power curves, and set to work. We had three main areas to deal with in tuning the car: the air/fuel ratio, timing and the VTEC changeover point. All Honda VTEC ECUs have two timing and two air/fuel maps, one for each set of lobes.
We attacked the fuel tables first and the timing second. To begin, we placed the VTEC changeover point at 8000 rpm to work on the low-speed cam and tried smoothing a fairly bumpy air/fuel ratio curve. Once the curve was fairly smooth, we experimented with both enriching and leaning the entire map until we saw optimal torque. Air/fuel ratios can be viewed and adjusted in either 2D or 3D graphs, though for ease of use in selecting cells, we used the 2D graph for tuning. By looking at the air/fuel ratio relative to the torque curve, we selected certain regions of the map and enriched or leaned them out.
There are several ways of accomplishing this, and by using keyboard shortcuts, we increased or decreased fueling using the default of 1 percent. We then switched to the timing tables, but never found much power from what was an already optimized map. We then set the VTEC point to 3000 rpm to work on the high-speed cam, where we found the most power, as expected, in the fueling tables. When both the low-speed and high-speed cams were tuned, we laid the torque graphs over each other, and where the torque curves crossed at 4900 rpm, we set our VTEC changeover point.
There are provisions built into the Hondata for widebands like the MoTeC PLM, giving those without access to a dyno an accurate way to tune. In addition, these widebands are ideal for part throttle or street tuning. Our Dynojet wideband plugged into the dyno itself, providing us graphs of torque versus air/fuel ratio. But with a MoTeC PLM, actual air/fuel values can be datalogged on the Hondata system and viewed next to the target air fuel ratio, or lambda, giving the ability to do an extensive amount of tuning sans dyno. In fact, all Hondata dealers are required to have a compatible lambda meter if they're equipped with a dyno. Tuning with a lambda meter, however, cannot provide for possible gains via ignition advance, something that must be done on a dyno.
Although the unit does not offer the same extreme precision of tuning ranges of some stand-alone systems, the Hondata box has proved itself on racecars as well. The Erick's Racing all-motor Civic Coupe, which is fitted with a Hondata, is the current IDRC world import record holder, with a 10.602-second quarter-mile run. Look for much more playtime with the Hondata unit as we explore other modifications, which will all require retuning for optimal performance.