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Whats the REAL Difference between a 90-91 ECU?

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MR2fanatic

Probationary Member
6
0
Feb 3, 2004
Hackettstown, New_Jersey
Guys,

FOR A TSI AWD 5 SPEED

Whats the difference between the 90 ECU and 91-94 ECU's? Are there some wires that are in different positions? Are the 91+ EPROM? Do the 91+ ECU's physically fit in 90 cars? Thanks for the help.
 
- All 90's are EPROM.
- 91's may or may not be EPROM

There are two wires swapped between the two ECUs.

Also, ECU has a wider range of fuel control on 91+ than on the 90's.
 
Originally posted by psychlow
- All 90's are EPROM.
- 91's may or may not be EPROM

You've got it backwards.
All 90's may or may not be EPROM.
- 91's are EPROM


Originally posted by psychlow
There are two wires swapped between the two ECUs.

True.


Originally posted by psychlow
Also, ECU has a wider range of fuel control on 91+ than on the 90's.

I'm not sure where you got that. Basis for claim?
 
91's do have a larger fuel trim swing and the Idle switch and MAF reset pins are swapped.90 and 91 both may or may not have Eproms.
 
I agree now that all 1G model years may or may not be EPROM after more research. All of the 90's I've seen were EPROM and I saw that written somewhere, but I was misinformed, sorry.

Fuel trims on 90's auto-adjust from 100 +- 20% if I remember right.
Fuel trims on 91's auto-adjust from 100 +- 40% if I remember right.

Don't quote me on the exact numbers! I'll see if I can find documentation to back this up.
 
90 ECU's have two pins swapped, change these in the harness and you can run the other ECU.

They are the exact same size.

90 fuel trims have a range of 40%, and 91+ has a range of 80%.

90's have less agressive timing maps, and slightly richer fuel maps.
 
Originally posted by Laser-man
all 90's are e-prom

Wrong, I have a 90 Laser and it didnt have an EPROM in it. When it took a shit I went to a junk yard and pulled 4 ECU in all the 90 cars they had and none of them were ERPOM's. The 90 ERPOM's are the hardest to find and very expensive. The one I found after three months cost me 300 bucks and didnt even come with an aftermarket chip.

Michael
:laser: :talon:
 
If you are doing a swap from a 90 to a 91-94 there is more then just swapping the wires on the ECU. You also need to swap the coil pack and ignition transistor from a 91-94 in. Also you don't need the noise filter any more, so you can just cut the plug off and connect the wires together. Here's a link to a more detailed description of the swap.

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