1992 auto ecu in 1990 fired right up?

[nfernotalon]

I just bought my 90 gsx it was bone stock when I bought it, checked the ecu right away to see I it was EPROM, no luck. I was going to send it out to get an EPROM conversion and borrowed my buddy's 1992 auto ecu so I can at least get to work while the ecu was at ECM.

I said what the hell I'll plug it in see what happens thinking it won't even fire up o the tach not work at least. Bam fires right up no issues tach works and idles fine

The car is stock checked the harness in the inside of the car and the engine bay, maybe someone rewired it. Doesn't look like it. It's still taped up with the same crusty oem tape. What gives

 

[nfernotalon]

Anybody?

 

[donniekak]

It wont run perfect unless you swap pins 6&14. The tach will not work correctly as the rpms get higher than idle.

 

[nfernotalon]

I did notice it was idling it 1400 hm. It should be right to drive for like a week to work right?

 

[1gchallenge]

i came across the same issue and i was about to start a thread on it. i just did a turbo swap to a 90 talon. i wired everything in for turbo like knock, maf, resistor pack. i put the 90 tsi ecu in and the car wont start. i replaced many sensors and finally i tried a 92 non turbo ecu out of giggles and it started and ran good...i didnt swap any wires from 90. i also have a 91 gsx ecu it starts with but runs bad even with 6 and 14 swaped. i just put the 90 na ecu in with 450 injectors and it starts revs and idles fine?! Is there anyone with any info on this at all???? ill start a new thread if no one answers to this because i cant find any info!