TypeSH

A friend of mine (Gernby) and I were looking at what it was going to take to do the ECU reset mod in our S2000's similar to how Marcucci's designed for the Prelude http://www.ntpog.org/mods/fifth-afc/ecu.shtml . This mod has been very beneficial performance wise in my Prelude since it erases the ECU memory every time you start the car. This allows removal of the catalytic converter and EGR valve in the Prelude since the ECU looks over consecutive driving cycles for problems in these systems. Since the ECU never sees consecutive driving cycles no MIL are ever thrown for these systems. This also resets the timing to stock every time you start the car, which will reset any retard in the timing caused from high temps or engine knocking.
Well I am not looking to remove the cat on my S2000 and since there is no EGR on our cars this mod's only useful function that I can think of would be to erase any retard on the timing. What makes this mod more interesting is that on the S2000 it requires no hacking into the stock wiring like the Prelude. As stated in the Helms Manual you can reset the ECU by removing the No. 25 fuse. The fuse is only for the backup of the ECU so effectively if you leave it out you will reset your ECU every time you start your car. If for some reason you get a MIL and you want to store the code all you need to do is insert back the fuse before you turn the car off. To Gernby and I we would rather do this than cutting into the stock wiring to put a switch. On the Prelude I did not have that option since it did not have a fuse just for the backup.
We tested this yesterday and it works as planned. If someone has mentioned this mod before I apologize. I have never seen anything on it for the S2000 so I just wanted to pass on this info to the masses.

Cheers

Gernby

Apparently, the A/C memory is cleared when the ECU clears. It is not that big of a deal, but it means that every time you start the car, you have to turn up the fan, hit the A/C button, and Recirc button (if you use the A/C at all).

1Randyc

Here is a little tibit before you really do this mod.
Obviously it takes a while to ecu to stabilize from the learning cycle. However, from my time to time experience from resetting the ecu, you will not be able to Vtec until the ecu stabilizes. This is probably the reason for precaution to check if the car is ready to Vtec safely.
I can attest that upon resetting the ecu, car pulls better and more responsively from the stand still, however what is the point of that if you can't vtec for a while until ecu lets you.
If you don't believe me, try the reset and punch the car to redline see if your car goes into Vtec.

Gernby

I have been using the car without the backup fuse for 2 days, and VTEC has been behaving normally. The only drawback that I have found has been the A/C control loosing its setting.

Utah S2K

Why???
I think you two need to get on Amazon and buy a couple of copies of "Getting to Know OBD-II". This book will give you the knowledge you appear to be seeking.

Utah

TypeSH

If you think this is not a good mod explain your theory to us instead of telling us to go read a book.

Gernby

[QUOTE]Originally posted by Utah S2K
[B]Why???
I think you two need to get on Amazon and buy a couple of copies of "Getting to Know OBD-II". This book will give you the knowledge you appear to be seeking.

Silver S2k Guy

This sounds very interesting. Besides the A/C settings getting reset (which I actually think is a good thing b/c I was told its not good to start your car with the A/C on so I have a habit of turning it off before I shut off the car) are there any other possibly harmful side effects to this mod. I guess it needs to be determined if it really does effect VTEC and if so for how long. Also does anybody have any actual data that shows an increase in performance by resetting the ECU...dyno or track results? I'm not doubting that this works I'm just curious of just how much of an increase in power we're talking about here.

Utah S2K

OBD-II is a very complex system, one which I am intimately familiar with. In short resetting it may increase hosepower as you note. But it's hit or miss.......Without a basic knowledge of short and long term fuel trim (i.e. STFT & LTFT) as well as a hundred other parameters why bother....why? Try this...reset your ECU......feel the power. Increase your altitude by 1,000 feet and feel the lack of power. Go get the book I noted and then pick up this software. The software will allow you see what changed when you reset you ECU.

http://www.obd-2.com/

Utah

Gernby

I understand what you are saying about the altitude ... if you live in a mountainous area, like Utah. However, here in Dallas, TX the max change in altitude throughout a days drive might equate to 50', and the main performance hit comes from heat and humidity. I want my ECU to adjust for environmental changes every time I drive it, instead of "remembering" to retard timing just because yesterday was particularly hot.