Is there any diffrence between the two?

 

They are all PM6

 

Yes and no. I know the 88 and perhaps the 89 have slightly different circuitry inside but they do the same job and can be interchanged 90 and 91. The fuel and spark maps in the 90 and 91 might be a little different cause the cams are different for those years but i've never noticed a difference when swapping the ecu.

 

The reason i wanted to know is on ebay they have ecu chips and one says if you dont have a 28 prong chip then you cant use it. I didnt know if there was a diffrence in chipping

 

88-89 cant be chipped. 88-89 have a 6800rpm fuel kill while most 90-91 have 7500 or none


[Modified by TorteX, 5:09 PM 1/25/2003]

 

The 90-91 PM6 ECU has different internals. The EPROM chip will only work in a 90-91 PM6. I would not recommend reving up to the 9000 RPM range of these chips considering the PM6 redline is 7100 RMP. On stock internals you will blow something up and you willl end up with this and this

 

I have two for sale if anyone needs one, just a note, my ecu out of my 90' Si is dated 1989 on the ECU.

 

In canada the if you use a 88 or 89 si ecu in a 90-91 si body you will get a electric load detector code as the 90-91 cras don't use a electric load detector