Meanshyguy

iTrader: (11)

I was talking to my friend yesterday and he said he was looking for a 97-00 ECU since it's supposed to yield better gas mileage. Is this true? He owns an SC300 and I own an SC400 so I was wondering if a newer ecu for my model would do just that, give me better gas mileage?

Kira X

iTrader: (24)

That's a good question! I don't know, but I have noticed that people with newer SC's seem to get way better mileage than the older ones.

Meanshyguy

iTrader: (11)

I read that SC400's give you about 18 city, 22 hwy, any improvement would really help, I'm buying a K&N air filter for now.

infiniti24

iTrader: (10)

i get 22 in the sc400 i have around town/hwy mixed 50/50 all hwy i get 24

Meanshyguy

iTrader: (11)

That's not bad.

SChema

iTrader: (2)

If I remember right, both the SC3 and SC4 switched over to VVT-i in 98. As far as just swapping the ECU over, I'm not positive that it will work. If it doesn't, the newest ECU you would be able to get is out of a 97 car.

Meanshyguy

iTrader: (11)

That makes a lot of sense thanks.

sc-driver

iTrader: (7)

switching ecu's won't work because for certain years Lexus changed around the sensors and sensor types.

92-95 ecu's are interchangeable
96-97 ecu's are interchangeable
98-00 ecu's are interchangeable

Switch them around and they wont work unless you plan on doing more work.

Miles per gallon is ALL about how you drive. On my 96 SC400 with ~120k miles I have gotten as low as 9mpg and as high as 27mpg average on the ENTIRE tank.

SChema

iTrader: (2)

9mpg, time-attack all day long?, lol.

sc-driver

iTrader: (7)

lol, it was when i first got the car and would floor it all the time. Also remote starting it every time with the a/c on didn't help either.

Klaus

iTrader: (1)

So different sensors for 96-97 than 92-95 because it is OBD-II that is correct. However, that doesn't mean the ECU won't work. For instance an OBD-II ECU on a 93-95 TT Supra is an upgrade as there is a lean spot in the OBD-I ECU that is remedied by this. It's plug and play, it's just that all your diagnostics and such will be off- but the car will run perfect. This is for the tt supra at least, it's probably worth a try with the 97 ECU.

TLDriver

iTrader: (4)

I never knew that. So if the OP would get a SAFC/II, NEO or whatever fuel management be an alternative "fix"?

sc-driver

iTrader: (7)

Check out this thread, it's very helpful.
https://www.clublexus.com/forums/per...fferences.html

Just know the #1 difference is in the maf sensors. In the 92-95 they use a karman vortex maf sensor. It uses 5 Volt pulses to determine the amount of air flow. While in 96-97 maf sensor, it uses a hotwire that determines the air flow from a voltage between 0 and 5 Volts.

@TLDriver, yes one of those piggybacks will work, but after a while the effects become diminished because the ecu starts adapting from those changes.

@Klaus, from what I understood, to get around that lean spot, people did the 12 volt fuel mod.

Well, if you try a 96 or 97 ecu on your older car, the worst that could happen is that it won't start. But like I said, if gas mileage is your concern, you need to first make sure your car is fully tuned up and then change up the way you drive.

The attached file is also a good read for anyone else who is interested.

Klaus

iTrader: (1)

12v fuel mod will just slightly help with that lean spot- it's right at the transition to the second turbo and it's build into the factory fuel map. There is also better gas mileage (slightly) with an OBD-II ECU

Meanshyguy

iTrader: (11)

I'm driving like an old man right now, lol, Instead of the ECU I'll just get a better air filter and maybe better plugs, anything that helps, I'm trying not to modify this car for racing purposes, I just wanna enjoy the ride