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i'm a bauce
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Discussion Starter #1
Hey guys just picked up a 2004 auto IS300. I’m using it to daily right now but it’s underpowered. I’ve been building N54 BMW cars for the last ten years so I’m missing boost. I need help deciding 1jz swap or NA-T this IS. I’ve read the is ecu is a pain to tune with piggybacks even at a moderate 6-9 psi. The 1jz really appeals to me as it’s 100% drop in but I’m needing a detailed write up to follow for the wiring. Has anyone here done it and can you help me out.
 

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Super Moderator
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The problem is the OBD-II stock ECU, and the CAN bus for the gauge cluster. Short of getting incredibly complicated with an OBD-II 2JZ-GTE swap ran in parallel with the stock ECU and all the sensors/etc needed to keep a stock OBD-II ECU happy, there's no way to add boost without getting rid of OBD-II compliance and/or living a neverending CEL life.

So long as you don't need OBD-II compliance, there's a lot of folks that have NA-T'd them or done all flavors of GTE swaps, and lots of writeups over at my.is
Personally I'd go with a simple NA-T kit for ~300-350whp and run a Haltech or similar modern ECU off of a wedge harness to keep the stock ECU for the gauge cluster and HVAC, and depending on your ECU, the VVTi functionality. OBD-II compliance goes out the window no matter what, though.

Alternatively, LS or Honda K motors both can be swapped in and OBD-II functionality hacked into functioning, and either of those engines with boost and an MT behind it would be a good match for the IS300 chassis. Sucks that it's such a bitch to keep it JZ, but that's the way it is sadly.
 

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i'm a bauce
Joined
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1,289 Posts
Discussion Starter #5
The problem is the OBD-II stock ECU, and the CAN bus for the gauge cluster. Short of getting incredibly complicated with an OBD-II 2JZ-GTE swap ran in parallel with the stock ECU and all the sensors/etc needed to keep a stock OBD-II ECU happy, there's no way to add boost without getting rid of OBD-II compliance and/or living a neverending CEL life.

So long as you don't need OBD-II compliance, there's a lot of folks that have NA-T'd them or done all flavors of GTE swaps, and lots of writeups over at my.is
Personally I'd go with a simple NA-T kit for ~300-350whp and run a Haltech or similar modern ECU off of a wedge harness to keep the stock ECU for the gauge cluster and HVAC, and depending on your ECU, the VVTi functionality. OBD-II compliance goes out the window no matter what, though.

Alternatively, LS or Honda K motors both can be swapped in and OBD-II functionality hacked into functioning, and either of those engines with boost and an MT behind it would be a good match for the IS300 chassis. Sucks that it's such a bitch to keep it JZ, but that's the way it is sadly.
I ended up gettin a SRT kit to turbo the car with a gt35r turbo. It’s a used kit but the turbo has zero miles and it’s complete and I got a good deal. Full turbo kit and fuel system. I can get my feet wet this way. I also picked up a Freddy emanage ultimate and boomslang harness for tuning. I’m not looking for anything over 300-350whp so this should be a fine set up
 

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What Wreckless said is really solid information. I've owned 2 different IS300s (currently have an 01 slicktop) and I really want to 'have my cake and eat it too' which practically necessitates running dual ECUs...particularly if you want to keep an automatic transmission and make the dash lights all happy. There is a lot of information over on my.is and I highly recommend that site for these cars. Congratulations for sure...they are truly special cars, and they don't make them like that anymore, very similarly to the MKIV Supra.
 
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