After doing some research I think I know all that needs to be done to get a 91-94 ECU to work in a 90, but I just want to make sure. This is what I have found so far. The MAF Reset line and the Idle Switch lines need to be swapped and you need to put in a '91-94 ignition transistor. Does anyone know if I'm missing something?

Andy could you explain a little bit the benefits of switching the ecu to the 91-94?

It's too hard to find an 90 EPROM ECU.

Like Ecoli said they are hard to find. From the research I have done the only 90 EPROM ECU's were in 1.6 Turbo Mirage/Colt/Summit.

Nathan Helder in Duluth did this swap, I believe all he had to do was switch around a few wires down at the ECU.

Did he do a 90 to a 91-94, or a 91-94 to a 90? I think you can just change the wires when doing a 90 to 91-94, and it will work. But when doing a 91-94 to a 90 you need to put in a 91-94 ignition transistor or the tach won't work.

I think you are right Andy. I know the 90's need a different tach input for the MSD ignitions.

I believe his is a 90 gsx, so he probably went from 91-94 to 90.

I found this site http://www.ecanfix.com/~mdhamilton/ecuconversion.html.

is there anything special about the eprom chip? is it just because you can slap a different chip in it?

Just want to put a chip in it. Like a TMO stage 3, up my rev limit.

Anyone heard anything about the DSM Chips?

Most of the chips floating around are just copies of the TMO chips.

The DSMchips stuff is good. The guy who makes the chips (Keydiver) has figured out a lot about the ECU recently. He can mod the chip to compensate for a hacked MAS and large injectors the correct way and a bunch of other stuff. I wanted to do some work on Mara's fuel enrichment maps if I ever got a working EPROM ecu to try to adjust for her hacked MAS, it seems he has already done the same thing and bunch of other MAS setups. Todd Day is all pissed about Keydiver selling the chips so cheap and having some of the same features of his old chips. He actually got Keydiver's chips kicked off EBay. Todd hasn't sold his chips for ages though and hasn't responded to previous customers requests for changes for ever. You can only have 1 RPM for the 2-step with Keydivers chips though, he didn't want to put in the pedal sequence changing ability because he thought it was too close to the way the TMO chips did it.

So which chip is better? And since I really don't care about the 2-step I'm guessing the DSM Chip is. Hopefully I'll be getting an EPROM ECU here soon and would like to get a chip.

Well, you can't even get a real TMO chip anymore. He has been ignoring the DSM community for a couple years now. People have been trying to get DSM.org from him also to get it back up and running correctly and updated. Some of the NABR guys recently copied all the old Talon Digests over to the NABR server before they disappear forever.

I am going to try the DSM chip, but I need to pull the ecu from my car first, find out which one it is, then order.

~John

Don't you have an AEM?

the 90 talon, not the galant.
Andy I think you have everything covered on your conversion.