Given that our ECM will eventually detune any mods regarding intakes, exhuasts, and AFC's, it seems that the best way of keeping the benefits of our mods without having to purchase a new ECM, would be to do a OBDII workaround. I've gone to the Prelude website in which instructions on how to do this was described. However, given that the ECM on the preludes are different than ours (s2000), i need to know which wire going into the ECM is the backup memory wire. If it helps any, the wire that i'm looking for is C10 on the 96+ Prelude. Which wire for the s2000 beats me!?!?! I went to to the Honda dealership and even asked the technicians there, and after searching through the ETM, and looking at the Data link connector and diagram (located by the driver's right knee - left hand drive cars), no one could tell me which wire is the one i'm looking for (backup memory for ECM). Please let me know as i would hate installing the AEM intake i just purchased, only enjoying the benefit's for a week or so, and then having the car co back to "stock" - without me having to disconnect the batter and reprogramming clock and radio settings.. blah blah. If anyone could help, that would GREAT!!!!!!!!

Sorry for the LONG post.

Best wishes,
Brian

 

Our ECU only learns at non-WOT (spreading the knowledge of Ultimate Lurker), to fix rough idles, etc. At WOT all your mods are definitely helping the car. To back that up, I've had my TB and Exhaust upgrade dyno'd 3 different times within a 4-5 month period, each one showed higher than my baseline - and they were all about the same. I recently added VAFC, it's likely that it will be dyno'd again before my next mods, so I'll have some more proof that the ECU did not adjust (negatively) anything at WOT.

 

Thanks for the bid of confidence..... But how often will i need the extra power porduced at WOT? I usually drive in traffic and where the increased power for me is in the lower end. In anycase, thanks again for the info.

Best wishes,

Brian

 

You may want low-end power, but still, it's probably WOT...isn't it? Kinda hard to expect to have power if you're not on the gas. I'm not sure what the ECU thinks is WOT, but I'd assume it's 50%+ throttle.

 

I think the ECU only *corrects* the a/f and ignition maps at non-WOT. The ECU goes to a fixed map for WOT, but will still use the MAP and determine fuel mixture based on MAP values. I don't believe exhaust will affect this, but I think that an intake will, or any manifold, TB, or head work. At least, this is based on what I know of the MAP and how it works (UL?!!!).

FWIW, I wrote that article (http://www.ntpog.org/mods/fifth-afc/ecu.shtml). I'm about to update it with some important new information:

The OBD2 "workaround" allows catalytic converter removal WITHOUT an MIL (Check Engine Light).

The OBD2 "workaround" allows EGR bypass without an MIL.


These have been confirmed on a '98 Prelude, and has been running fine for a week now. I can't say that the '99 or newer (OBD2.?) with the "new" OBD2 will still work like this, but it's at least promising for older vehicles.

UL's beef is that the spark "learning" is advantageous, and what the ECU "learns" during non-WOT is applied to WOT driving. If you search for OBD2 and look at some older posts you should find a "discussion" we had on the topic.

I don't have enough mods to have affected it, but I don't think the S2 runs horribly rich (not near as much as the H22). I believe cdelena found that even with header/exhaust he only had to reduce his fuel pressure to the bottom end of the stock "window" to get it to make the most power. I can't remember what he's running for an intake.

My jury is out- I'm not sure the workaround will buy much on the S2, but I don't have enough mods to be able to tell. I'd love to lose the cat, and for that, the workaround would be a cheap alternative to an AEM or Mugen ECU.

Brian, if you want to know that pin number, email me and I'll check it in the manual when I get home. I can also scan the connector location, I've got the ETM as well. Lastly, if you like ntpog.org, check out s2000.org.