What is it about these that makes it...impossible?

 

Traditional automotive ECUs store fuel and timing maps on a ROM or EPROM. When people talk about "chipping" and ECU, they are either reprograming or physically replacing the ROM chip with the data on it.

The 5th gen ECU has no separate ROM chip for fuel and timing maps. All of the maps on the 5th gen ECU are hard-coded in the on-board memory of the ECU's primary microcontroller. To change them, you would need to change the microcontroller itself.

Andrew

 

in lamen's terms, you can't chip an OBDII ECU, you would need an OBDI GSR ECU and a OBDII->OBDI conversion harness, and then have the GSR ECU chipped.

 

Thanks, that explains it. How much would it cost to have the conversion done?

 

skunk 2 sells a harness, i think it's about $235 or something, but it would be well worth it performance wise, since OBDII is way more enviromental, and OBDI is better performance

 

So, the harness would run me $235, but what vehicle uses and how much is an OBDI GSR ecu, plus a chip? Also, do u know what kind of gains would I get from this? Thanks again man


[Modified by osuPrelude, 10:56 PM 10/18/2002]

 

94-95 Integra GSR, or a 93-95 Prelude VTEC model will be your best bet. if you can find either one of those ECUs then

 

you can get the harness from kenji on this board or here http://www.c-speedracing.com/frame.html for $200....i think you can use a P28 ecu from a vtec civic also

 

a P28 won't control the secondary butterflies on the intake manifold

 

This is a dumb question, but I have to learn like anyone else. I haven't read much about ECUs on Preludes, well any car for that matter. I always here about how the OBDII ~~> OBDI conversion is well worth it performance wise. My question is, what exactly makes it better, what does it allow you to do, and what are some long run gains it can provide for the Prelude? Yeah, these are my noob questions for the day, thanks guys

 

ok, basically, OBDII stuff is a lot more emision strict. i don't think their will be a great advantage on a Prelude though unless you are going to use a chipped ECU. if any of you have an air/fuel guage in your 5th gen, you will notice that it seem like it is ALMOST ALWAYS rich. they're is a lot of specualtion to how much it will help. i never chipped mine while it was N/A b/c it was bottle fed, and one thing that a chipped ECU does, is advance the timing, which can cause detonation.


EDIT: if anyone else has better insight into this, please comment, i've never researched this too much, so i dpn't know a lot of specifics.



[Modified by Boosted97Lude, 12:34 PM 10/19/2002]

 

check out the info at http://www.hondata.com (they also sell the OBD-II>OBD-I Adaptors plus they have a list of what ECU's will work with what cars

 

i can get ya a harness and help find you an ecu.. i can get it chipped all at the same time if you are interested.

check sig. and email me for major details and questions


but yeah, the obd1 are better in the fact also that they are cheaper and there is more around then the newer obd2. plust the fact that they can chipped and other gains


[Modified by KTeller8, 10:19 AM 10/21/2002]

 

I have a 5th gen running on p28 and s200. No issues. I believe a p72 was the best choice for 5th gens but the knock sensor on the stock unit is not accurate so taht isn't needed. I have no issues with losing the secondary intake runner control.

So the parts were obd2 to obd1 harness, p28 chipped, and s200 for me.


[Modified by Anubyss, 11:48 AM 10/21/2002]