[Diy_efi] Another Eprom Question

[mbelloli at speedymotorsports.com]

     That is basically what I have now, but it is setting the check
engine.  And you will have basically a prom error, and the vehicle
running off something other than the chip.  It runs like crap.  This
is in a 1993 Acura Integra with a GSR motor, and a p28 computer. 
Stock came with a 27C256.  It already had an eprom in it.  Now it
doesn't do it every time.  I like every third time it will set the
check engine lamp.  you'll have to clear codes, or disconnect the
battery to get it running correctly again.

Thanks,

Marcello

>  Back in 87 I was running a 27C512 with 4 programs on my Buick GN...
> had a small board the chip was on and a shielded ribbon going to the ECM.
> would toggle the 2 highest address bytes with a thumbwheel on the dash to
> change banks and did it on the fly all the time with no CE light.
>
>
> -------Original Message-------
>
> From: mbelloli at speedymotorsports.com
> Date: 01/25/05 15:13:07
> To: diy_efi at diy-efi.org
> Subject: [Diy_efi] Another Eprom Question
>
> Hello everyone,
> I have been pulling my hair out trying to figure out another one of
> these chipping ideas. I am trying to set up a controller to allow
> the switching of which chip the ecm of a car computer is running on
> the fly while driving. Currently I've got it working very well if
> you switch with the key off, but not while running. The original
> chip was a 27C256, which switched out for an ATMEL AT29C010. I
> really only wanted 4 choices, which this chip more than allows. I am
> trying to set it up so I can have pic processor do the switching for
> me. I cound't put a picture of the waveform that is driving me crazy
> here so I put it on my website at
>
> https://home.comcast.net/~hexibot43/ChipEnableLogic.htm
>
> I just can't understand why it is working right now with the signal I have
> on the Output enable pin. From what I understand it shouldn't be working,
> but it is working. I thought I was going to simply look at the signal,
> and see drops to ground like I did with the last car computer I looked at.
> I figured I could use that as a trigger for an interrupt the would in
> turn wait a set amount of time and then switch banks. This way I could do
> the switching when the chip was not be read from, and so the ecm would be
> happy and not throw an check engine lamp at me.
> Can anybody sheld some light on this for me? You guys did so well
> helping me last time, I hope you can do it again. And yes, I still
> have a lot more to learn.
>
> Thanks,
>
> Marcello
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