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httrdd
10-21-2011, 08:34 AM
Will my 99 LGT ECU work with a 99 Rs? Is it the same dohc or are those sohc?
phi11
10-21-2011, 10:29 AM
98 RS is Dohc, (Usdm)
99 RS is Sohc,
So, no.
chuckthefuk
10-21-2011, 11:04 AM
IIRC

99-01 RS = EJ251 = MAP / SOHC
96-99 LGT = EJ25D = MAF / DOHC

Doubt it will work..

Damn you phi11. for beating me to the post!
httrdd
10-21-2011, 11:54 AM
Yea I though 99 was sohc, but was not sure. Thanks.
grayguy
10-21-2011, 08:33 PM
A 99' RS is MAF based. Of the wiring harness physically fits, it'll work. My 98' GT has the stock (25d) ECU and runs an 01' RS Sohc motor (converted from MAP to MAF) just fine.
chuckthefuk
10-21-2011, 08:43 PM
Ahh I stand corrected....

But Seriously?

No issues with the cam sensors?
elislider
10-21-2011, 09:01 PM
The 98 RS and 98 Forester are MAF based EJ25D (DOHC) and very similar if not the same as the 96-99 Legacy GT (more similar to 98/99 LGT I believe, since the 96/97 LGT/Outback were hydraulic lifters and 98/99 LGT/RS/Forester is shim over bucket valvetrain). Then the 99 RS and 99 Forester are MAP+MAF (1 year only) SOHC, then 00+ is MAP only SOHC.

A 99' RS is MAF based. Of the wiring harness physically fits, it'll work. My 98' GT has the stock (25d) ECU and runs an 01' RS Sohc motor (converted from MAP to MAF) just fine.
My understanding is this would only be possible if you swapped to phase 1 cam and crank gears, and the 01 RS intake manifold and then used your EJ25D wiring? seems like a weird project to do when you could just swap the shortblock and not have to change anything else


Ahh I stand corrected....
But Seriously?
No issues with the cam sensors?
see above.
httrdd
10-21-2011, 09:38 PM
Great maybe i can get this thing sold to buy more parts.
phi11
10-21-2011, 11:33 PM
The 98 RS and 98 Forester are MAF based EJ20D (DOHC)

they would be EJ25 not EJ20.

I have a '98 RS engine in my '98 GT!
grayguy
10-22-2011, 12:50 AM
My understanding is this would only be possible if you swapped to phase 1 cam and crank gears, and the 01 RS intake manifold and then used your EJ25D wiring? seems like a weird project to do when you could just swap the shortblock and not have to change anything else


I didn't swap anything besides the injector clips, IAC clip, coil pack clip and the purge control. No internal motor swapping at all. It runs great, the only codes it throws are for a bad o2 sensor.

The reason I bought the Sohc was because it was complete and runable, and around here it's very difficult to find a running 25d, and the dohc 25d heads cost around $500 to rebuild so it's just dumb to bother with them when you have a good set of Sohc heads already ready to rock and roll.
elislider
10-22-2011, 01:22 PM
^^ color me surprised it was that easy, but i suppose anything is possible. generally it makes more sense to just swap the shortblock or longblock if possible and keep all the intake and wiring original



The 98 RS and 98 Forester are MAF based EJ20D (DOHC)
they would be EJ25 not EJ20.
I have a '98 RS engine in my '98 GT!
haha whoops that was a typo. thanks for noticing