Chip burners jump in !!

[Sgreg]

Can someone tell me what is the primary difference in the memcal/prom used in the 1990 and 1991 ZR-1 with factory ECM 1228331 ? I have always heard one should not use a 90 in a 91 even though the ECM is the same. Please tell. :cheers:

[Zr1 Destroyer]

I'm not sure why, but I can tell you first hand I tried a 91z chip in my 90z about nine years ago and was a no go......no secondaries at all!

[-=Jeff=-]

The MAIN difference is the Knock Sensor stuff. on the 1990 the is an external module for the knock sensor, in 1991 it is that PC board on the MEMCAL (PC board is over the 2 smaller ICs) and is not present on the 1990 MEMCAL.

ALSO:

Power Switch is connected to a different location C9 on 1990 and C18 for 1991 and later

Injectors 5 and 7 are swapped from 1990 to 1991 and later

I need to double check the Injectors in my red book to be sure, but that is the data I have..

Now, you could take some of the table data out of the 1991 Binary and transplant them in a 1990 Binary..

[Sgreg]

The MAIN difference is the Knock Sensor stuff. on the 1990 the is an external module for the knock sensor, in 1991 it is that PC board on the MEMCAL (PC board is over the 2 smaller ICs) and is not present on the 1990 MEMCAL.

ALSO:

Power Switch is connected to a different location C9 on 1990 and C18 for 1991 and later

Injectors 5 and 7 are swapped from 1990 to 1991 and later

I need to double check the Injectors in my red book to be sure, but that is the data I have..

Now, you could take some of the table data out of the 1991 Binary and transplant them in a 1990 Binary..

So, Jeff, you are saying a top notch tuner can make changes to the 90 prom to work with a 91 ? Maybe too much trouble ??

[Jeffvette]

Greg, I can *loan* you a 91 prom to get through emissions. Although there should be no reason why your car won't pass with a modified prom.

[XfireZ51]

So, Jeff, you are saying a top notch tuner can make changes to the 90 prom to work with a 91 ? Maybe too much trouble ??

The parameters in the calibrations are mostly the same. The primary params like VE, SA, etc are the same. So its just a matter of copying those tables over to the corresponding MASK ID for that year. Not sure what the gain would be. So you can take the 91 settings and copy them to a 90 chip. But that won't allow you to plug a 90 chip into a 91. There are physical differences as =Jeff= has described.

[-=Jeff=-]

So, Jeff, you are saying a top notch tuner can make changes to the 90 prom to work with a 91 ? Maybe too much trouble ??

more then likely Yes..

Looks like Jeffvette might have the answer for you too though..

what is failing on your car?

[Sgreg]

more then likely Yes..

Looks like Jeffvette might have the answer for you too though..

what is failing on your car?

Always seem to have high NOX values with performance chip. Suspect the factory chip sets a richer mixture ?

[-=Jeff=-]

Always seem to have high NOX values with performance chip. Suspect the factory chip sets a richer mixture ?

hmm. richer is relative depending on the mods you might have done..

what is done to the car? is the AIR pump still inplace? hot wire it to run during the test

[Sgreg]

hmm. richer is relative depending on the mods you might have done..

what is done to the car? is the AIR pump still inplace? hot wire it to run during the test

Jeals, RT's, P&P plenum and inj. housings, Corsas. No air pump.

[Sgreg]

Greg, I can *loan* you a 91 prom to get through emissions. Although there should be no reason why your car won't pass with a modified prom.

Thanks for the offer, Jeff. I have a while to find a stock 91 to buy. Hate to call you every year !!! :mrgreen: