Whats the REAL Difference between a 90-91 ECU?

[MR2fanatic]

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]

- 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]

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]

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]

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.

 

[psychlow]

Some stuff:
http://www.hywell.org/plhelp/lo.html
http://www.vfaq.com/TMO/ (CTRL+F, search for "trim")

 

[kpt4321]

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.

 

[Laser-man]

all 90's are e-prom

 

[boostedinaz]

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

 

[LightningGSX]

Originally posted by Laser-man
all 90's are e-prom

I own a 90 tsi and a 90 eclipse turbo FWD, neither have Eprom ECU's.

 

[MnDSMer]

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

 

[DevilSperm]

TPS and CAS are also different ...if your doing the swap

 

[1990EclipseGSX]

Again, all 90's DO NOT HAVE E-PROMS! I have a 90 and man was an E-PROM ECU a real PITA to find. Also ran me a pretty penny.