1G 90 EPROM in a 91 car

[pnklmnd]

Ok guys, i have been led allover the place and come up with nothing.

I have a 1991 Talon TSI AWD. I have a 90 EPROM ECU in the car. I was told it doesn't work right. Like the RPM doesn't work correctly. So i researched a lil more and then was told you can cross two wires and have it run fine. My main concern is i want to get DSMLink (who doesn't right?), but if my RPM is going to be messed up and wont read correctly then how am i supposed to use it.


So basically i need to know can i cross two wires and have it work. Or was who told me that, full of crap.

 

[ISUJakey]

Just out of pure curiosity, since '90 EPROMs are worth a mint, why not sell your ECU and pick up a '91-'94 EPROM for much cheaper? You'll be money ahead and have the "correct" ECU in your car.

 

[dsm-onster]

Ok guys...i have been led allover the place and come up with nothing.

Ok well i have a 1991 Talon tsi awd. I have a 90 ePROM ecu in the car. I was told it doesnt work right. Like the RPM doesnt work correctly. So i researched a lil more and then was told you can cross two wires and have it run fine. My main concern is i want to get DSMlink(who doesnt right), but if my RPM is going to be messed up and wont read correctly then how am i supposed to use it.


So basically i need to know can i cross two wires and have it work. Or was who told me that, full of crap.

If you switch a pair of pins then the 1990 ecu will work fin in your 1991-1994 harness. It is the other way around that the tach is affected. See here about that. However, all you need to do is swap the pins highlighted in the link below:

http://www.ecanfix.com/users/mdhamilton/ecuwiring.html

 

[kanderson111]

I believe there is a little more to it than two wires.

Somewhere there is a write up on it, complete with pictures. The instructions were actually the opposite though, they were for using the 91-94 EPROM ECU on a 90 car.

Like the guy above said it may be better to find the 91-94 EPROM ECU because these are abundant and the 90 ECUs are rare. Plus it seems like it was a lot more involved than a couple of wires. They showed changing a plug and rewiring that harness for the fuel injectors.

I think dsm-monster answered your question. Sorry he must have been posting at the same time I was.

 

[pnklmnd]

Just out of pure curiosity, since '90 EPROMs are worth a mint, why not sell your ECU and pick up a '91-'94 EPROM for much cheaper? You'll be money ahead and have the "correct" ECU in your car.

There worth a mint? Here they are useless . If you have a good 91+ wanna trade?

I was sitting on two 90 EPROMs and sold them both for 20 bucks. If anyone has one I'd rather buy one from them. I got cash, that's the route I'd rather go, but we have no 91+ EPROMs here. Checked dozens of times....

Let me clarify EXACTLY. I cut wire 6 and 14. Solder wire 6 to the wire ECU side of 14. Solder wire 14 to the ECU side of the 6 wire?

DSMmonster, so those two wires i just cross the wires? Cut solder and heat shrink? And its for the airflow?

Hmmm its wierd, the only problem i had when running the 90 was my tach didn't read right, and I got idle surge pretty bad unless i tuned the car lean when i idled it.

 

[oldman]

There worth a mint? Here they are useless . If you have a good 91+ wanna trade?
I was sitting on two 90 EPROMs and sold them both for 20 bucks.

Useless, how so? They are in high demand because it's a lot more difficult and involved to put a '91+ ECU in a '90 car, a working '90' EPROM ECU is worth at least $250.

 

[pnklmnd]

where im from there are 90ecus out the wazoo is what im trying to say. And most of the people in are little "DSMcircle" are all 91+.

 

[GVR4592]

You could make a small fortune selling 90 ecu's. I just sold my last one for $125 for a non-eprom. I usually try to have at least 2 because people are always needing them.

 

[steve]

Let me clarify EXACTLY. I cut wire 6 and 14. Solder wire 6 to the wire ECU side of 14. Solder wire 14 to the ECU side of the 6 wire?

You don't cut the wires, you release them from the connector and swap pins 6 and 14. It takes about 30 seconds to do.

The pins in question are for MAF reset and the IPS. These swapped position in the connectors betweern 90 and 91+. My car always runs like crap if I forget to swap the pins when testing ECUs.

Steve

 

[sweet97]

YEP! I bought a socketed '90 EPROM ECU from ffwdconnection last year for $330. and swapped the 2 wires like Steve said. Works just fine. MarkPS: FFWD is getting $400. for a socketed ECU now-1G that is.