One of the tricks we used to use on OBDI cars was an ECU reset, particularly just before making a pass at the dragstrip. I thought I'd see if doing the same on the S2K would have any tangible effect.

I pulled the 7.5A backup fuse, let the car sit for a minute and then put it back in. Now here's where it gets interesting. The day before I had been demonstrating to a friend how awesome the car sounds with the airbox cover off. I left it off when I put the car away and did not replace it before restarting the car after reset. Once the car had warmed up, the next stoplight I came to, it stalled on me! I had heard people mentioning issues with this before, but had never experienced it. After a few miles, it no longer wanted to stall, as though the ECU had adapted.

Next, I put the cover back on and proceeded to drive around. I also made a couple hand timed speed interval passes (40-60, 50-70, etc.). Now, I don't remember my exact times from the past, but the car seemed slower than before (my street launches, which usually netted me 6.2-6.3 0-60 times were now returning 6.8-6.9). Didn't feel any slower, but my stopwatch times are reasonably consistent, if not absolutely accurate.

I don't know what to make of it yet, but I'm going to reset tomorrow morning with the airbox lid on and see what happens.

UL

 

After any modification you should:
1. Pull the back up fuse for 30 seconds.
2. Install the fuse and start the car.
3. Let the car idle w/o any accessories on for 5 minutes.
4. Turn off the car and then you're ready to go.

Sense the computers run off of MAP, they have set parameters that they must follow. BTW, about every seven starts, the computer resets itself so that it can "learn" any new conditions.

 

[QUOTE]Originally posted by Knowledge
[B]After any modification you should:
1.

 

Let me second that "are you sure?" Also, UL, I thought it was you that told me that some things like the spark map need to be adapted and that resetting the ECU is bad. I had wired my '99 Prelude to *not* have backup power at all; I pulled that wire to the ECU from the 7.5A backup fuse. Made a world of difference.

I would think that while the engine sounds nicer with the airbox cover off, that would change quite a bit in terms of airflow. The stock "cold air tub" has the "snorkel" to the area just in front of the rad, which should be a high pressure area at speeds much over 20 or 30. Did you previous hand-timed intervals occur with the top of the airbox off?

 

Yes, I'm sure. Let's say that your CEL comes on. You pop the hood and one of your spark plug wires accidentally got pulled off a spark plug while you were working on your car. You can do three things to "fix" the CEL. One, disconnect the battery for 5 minutes, two, remove the back up fuse for 30 seconds, or three, just drive your car like it's not even there. After 7 or so engine starts/stops, the CEL will go away. The point is, all of these accomplish the same thing, resetting the computer. The only real difference is that they take different amounts of time.

 

One more thing, Hondas run on what is called a closed system. Under full throttle, things like fuel injector duty cycle, igniton timing, etc. all use a default parameter. Cars that use an open system can adjust these components while on the fly. So, when you make a modification, e.g. a header, and you don't reset the computer, you aren't letting it immediately "learn" that flow characteristics have changed.

Also, if you drive in the city all the time and you're going to go on a long, highway trip, try resetting the computer right before you leave. Same goes for vice-versa. You may be surprised to see how much your gas mileage can improve.

 

The OBDII is much different than OBDI. We all know that it is adaptive, and this takes a while. There are special tools now available which can store the "learned parameters", so that they can be restored after working on the car.

This was due to the fact that performance loss has been occuring during the reset process, and can take a couple weeks to come back completly. Shops needed this so that customers picking up there cars didn't leave with the feeling "My car is running worse than it did before I brought it in".

 

[QUOTE]Originally posted by Knowledge
[B]One more thing, Hondas run on what is called a closed system.

 

[QUOTE]Originally posted by Knowledge
[B]One more thing, Hondas run on what is called a closed system.

 

[QUOTE]Originally posted by Knowledge
[B]One more thing, Hondas run on what is called a closed system.