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Whats the REAL Difference between a 90-91 ECU?

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.
 

psychlow

Proven Member
2,866
13
Jun 30, 2003
Colorado Springs, Colorado
- 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.
 

Morphius

DSM Wiseman
1,897
56
Jun 9, 2003
M-Town, Michigan
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?
 

LightningGSX

Proven Member
628
4
Jan 15, 2003
St Paul, Minnesota
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.
 

psychlow

Proven Member
2,866
13
Jun 30, 2003
Colorado Springs, Colorado
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.
 

kpt4321

Proven Member
3,393
13
Jul 30, 2002
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.
 

boostedinaz

DSM Wiseman
3,839
16
Dec 22, 2002
Scottsdale, Arizona
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:
 

MnDSMer

Proven Member
11
0
Mar 25, 2002
MinnesotaUS
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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