So I bought another 90 gsx and I found out it has an EPROM ECU in it. According to the EPROM chip numbers over at dsmchips.com the number on the chip is a CA number. I am planning to swap this ECU into my other car but it has a FED ECU. Will it work with no problems?

I believe it won't be happy unless it sees an EGR solenoid.

http://members.shaw.ca/costall/1000Q/answers-makeandmodel.htm

"What are the differences between Federal cars and California (CA) cars?
CA cars have more stringent emissions requirements than Federal cars, so they have a couple of extra pieces of equipment. An exhaust gas recirculation (EGR) solenoid valve is installed on CA cars next to the fuel pressure solenoid valve, while Federal cars have a empty space there. 1G CA ECUs are programmed slightly differently than Federal ECUs, making it problematic to switch ECUs from car to car without getting error codes."

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You can switch a CA car to a fed car put cutting one of the resistors. I think its is resistor 129, or maybe 130. This will switch the car over to the other mode. To switch it back you have to resolder it.

I concur with Defiant & thegreatms :
I've swithched from a CA to a Fed with no problem but:

If you switch from a Fed to a CA ECU your gonna throw at least an EGR code and possibly other problems as well. If your interested there's a link below to a post that shows a schematic of FED- CA differences in vaccum solenoids. The 1st one is Fed the second is a CA.

http://www.dsmtuners.com/forums/showthread.php?t=133451




Good luck

According to my notes all you have to do is solder in a 1K resistor into the R129 position. California ECU's don't have a resistor there, and Fed ECU's do. That's all.

yup just the resistor

The resistor in the R129 position replicates the the resitance of the EGR?

terefic181 said:

The resistor in the R129 position replicates the the resitance of the EGR?

Click to expand...

Nope. The resistors in the 129 and 130 position tell the ECU which car it's in (Fed or CA). If R129 is present, the ECU knows to ignore the EGR check for emissions. If there is no resistor in the R129 position the ECU will look at the EGR temp sensor resistance and throw a CEL if it fails.

Cool....... I stand corrected We keep learning here.........

I have a somewhat similar question. I just bought another 91 talon and its got an eprom in it but its an automatic, now can i switch that into my 92 manual without any problems? My 92 also has an eprom but i dont want the downtime of sending out my ecu to get socketed. All help is appreciated.

Thanks fella's.

pneumo said:

Nope. The resistors in the 129 and 130 position tell the ECU which car it's in (Fed or CA). If R129 is present, the ECU knows to ignore the EGR check for emissions. If there is no resistor in the R129 position the ECU will look at the EGR temp sensor resistance and throw a CEL if it fails.

Click to expand...

I know this is a somewhat old post but based on what I've seen the config resistor behaviour applys to 91-93 ECU's. The 90 ECU had different software versions between Federal (E742) and California (E743) and that is what makes up the primary difference between the MD145903 Fed ECU from the MD145902 CA ECU. The '94 ECU are all CA spec so again the resistor doesn't seem to have much impact.

If somebody has a 90 ECU that works differently (actually changes using the resistor) I'd like to know about it.

Steve