ECU with no ROM adapter

[TomsSVX]

Originally Posted by b3lha

AFAIK Fitting LAN's eprom should convert it to a 92 ECU, so shouldn't be any problem with the sensor.

Not correct. LAN's chip only modifies the fuel timing and knock correction as far as I know. He does not access any other parameters such as the EGR temp sensor. i install a 94 ECU into my car with a ECUtune chip and I still got the CEL. i installed the 92 ECu with the same chip and got rid of it. There is no wiring or a sensor in the circuit on the 92's

Tom

[immortal_suby]

it sounds like you have quite a rare ECU there! my wife had a 6/91 build with a rom socket soldered in. Very interesting to hear they used something different for one month of production. I'm also surprised this is the first we've ever heard of it. Don't lose it.

[nextse7en]

Well sir, if things don't go as planned at the salvage yard, I'll ship you a spare for 30 bucks.


-Patrick

[Nomake Wan]

Originally Posted by TomsSVX

Not correct. LAN's chip only modifies the fuel timing and knock correction as far as I know. He does not access any other parameters such as the EGR temp sensor. i install a 94 ECU into my car with a ECUtune chip and I still got the CEL. i installed the 92 ECu with the same chip and got rid of it. There is no wiring or a sensor in the circuit on the 92's

Tom

Actually, I have to question you on this one. When you cut the resistor on the ECU, the ECU ceases to read from any internal memory. Every bit of information for all engine function comes from the socket once the resistor is no longer there. LAN's code is based on a 1992 ECU, so it should have all the same functionality as a 1992 ECU (except for anything that LAN edited). I believe that's what Phil was referring to.

Maybe there was a wiring difference in the harness causing the CEL?

[TomsSVX]

no... I am sure Mike copied everything from his 94. But as far as I know he is only tampering with the maps while everyhting is still a function of the ECU itself. i could be wrong though

Tom

[Nomake Wan]

Originally Posted by TomsSVX

no... I am sure Mike copied everything from his 94. But as far as I know he is only tampering with the maps while everyhting is still a function of the ECU itself. i could be wrong though

Tom

I just wonder how that's possible. But for that I'd have to know more about what exactly changes when you cut the resistor at location J1.

[TomsSVX]

that would probobly be the answer to the questions since Mike wouldn't tap into the IAC circuit at my request either

Tom

[mikecg]

Originally Posted by TomsSVX

Not correct. LAN's chip only modifies the fuel timing and knock correction as far as I know. He does not access any other parameters such as the EGR temp sensor. i install a 94 ECU into my car with a ECUtune chip and I still got the CEL. i installed the 92 ECu with the same chip and got rid of it. There is no wiring or a sensor in the circuit on the 92's

Tom

He alkso tweaks the timing around some. But I believe your correct about all the other stuff. I know I still have the speed cut off on mine. Not that it really matters when your gear ratio puts you at redline when you get to that speed.

[b3lha]

As I understand it, when you cut the resistor, the internal ROM is totally disabled and the ECU uses the external ROM. LAN's ROM is a copy of the Subaru ROM with some changes made to the fuel and timing maps and the constants (rev limiter etc). I thought he based it on a 92 rom, but maybe it was a 94.
I can't explain your observations. As far as I know, the original year of the ECU should be irrelevant because its code is completely replaced by the code on LAN's ROM.

Regarding the USDM 94+ speed limiter. I can see the 180km/h limiter in my JDM ROMS and I would expect the USDM limiter to work in the same way. However, I cannot find any deliberate speed limiting in the 94 USDM ROM that UPnorth362 sent me. The only suggestion I can make in this regard is that perhaps it is a bug rather than a feature. ie. a variable maxing out or dropping off the end of a map.

[GTOSVX]

Picked up replacement ECU, (twice, the first one was wrong part number) and installed as simply as it was designed to be.
thanks for all the support.