General Stupid Q: 90 EPROM ECU work in 91?

[yotabeater]

I found a 90 EPROM ECU for a good price, but I heard they are different than the ones in 91-94's. Also does it matter if it's auto or 5 speed, fwd or awd? Stupid questions, but my brain hurts from reading so much. thanks. -Josh

 

[slow95tsi]

it will work, 1g ecu's will interchange and 2g ecu's will interchange (as long as there turbo)
but 1g and 2g ecu's wont interchange with each other

 

[RoasT BeeF]

It wont work unless you switch two wires on the ECU harness.

Look at vfaq.com man, it has your answer.

 

[90AWDTalon]

I found a 90 EPROM ECU for a good price, but I heard they are different than the ones in 91-94's. Also does it matter if it's auto or 5 speed, fwd or awd? Stupid questions, but my brain hurts from reading so much. thanks. -Josh

I have a '90 Talon and a '91 EPROM ECU, it might be worth it for us to trade. They won't work with out some modifications. I don't know what it takes to make the '90 ECU work on a '91-'94 car, but to make the '91 ECU work on my '90 Talon, I need to switch pin numbers 6 and 14, and swap the coil, transistor, and tach to '91 specs. Mine is out of a fwd auto, but that doesn't matter if you plan on putting a new chip in. I haven't gotten mine socketed yet or installed it. I was just about to order the chip when I saw your post. So let me know if you might be interested in trading.

 

[steve]

also does it matter if it's auto or 5 speed, fwd or awd?

Once you change the code in the EPROM it doesn't matter which it was originally. Since there weren't any '90 Auto's that's not an issue. AWD vs FWD won't be noticable with the stock code. FED vs CA is the other issue with '90 ECUs and requires a new EPROM to change unlike the later ECU's where you can change a resistor.

As RoasT BeeF says you have to swap pins 6 and 14 since they changed the location of the IPS and MAF reset lines between 90 and later. (The pins pop right out of the connector with a tiny jewelers screwdriver to lift the pin retainer after pulling the black lock out of the middle)

Steve

 

[90AWDTalon]

Theres more to it than just switching those two wires.

http://www.ecanfix.com/~mdhamilton/ecuconversion.html

 

[steve]

Theres more to it than just switching those two wires.

http://www.ecanfix.com/~mdhamilton/ecuconversion.html

That only applies to putting a '91+ ECU into a '90 car. From the topic I believe we are talking about putting a '90 ECU into a '91 car so the only wiring issue is swapping pin 6 and 14. I do it every time I test a '90 ECU after repair. It takes me less than a min to release the pins and move them.

Steve

 

[kyledykstra]

That only applies to putting a '91+ ECU into a '90 car. From the topic I believe we are talking about putting a '90 ECU into a '91 car so the only wiring issue is swapping pin 6 and 14. I do it every time I test a '90 ECU after repair. It takes me less than a min to release the pins and move them.

Steve

Really?? That's good to know, I thought you had to do all the same things (coil pack etc etc). Does the 91+ tach work fine? I've got a '93 auto w/all manual engine, and I've got a '90 manual ECU and cluster, if all it takes is to just switch the pins, I'll do that this afternoon!

 

[90AWDTalon]

That only applies to putting a '91+ ECU into a '90 car. From the topic I believe we are talking about putting a '90 ECU into a '91 car so the only wiring issue is swapping pin 6 and 14. I do it every time I test a '90 ECU after repair. It takes me less than a min to release the pins and move them.

Steve

The tach works this way?

 

[steve]

The tach works this way?

On a '91 car with a '90 ECU it seems to. I don't drive for days like this but I've never noticed a problem with the tach during the test drives.

Steve