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Discussion Starter · #1 ·
Hi all, I am new to the IS300 scene but definitely not new to Supra's. I recently acquired a 2001 IS300 with a VVTi swap running stock turbos/stock aristo ECU, stock aristo tranny, and a wiring harness from Dr. Tweak.

The previous owner said that it ran perfectly fine at the point of sale however in his earlier posts he complained of the same issue. He said it was "fixed" by replacing a bad throttle body. I am confused because it appears to have the exact same issue but I don't believe the throttle body is the culprit. It only occurs at a higher load/partial throttle boost. It drives fine when I am going on a straight road/no uphills, no boost, lower speed (lower load essentially). I checked the BOV and there are no leaks and it is recirculating.

Example: It is fine at WOT (except for boost cut...which the car wasn't equipped with a boost controller or a BCC....). However when I get around freeway speeds it can't maintain steady speed because the load is higher and it begins to stutter. Almost like it goes rich? The previous owner said the problem only occured around 2-2.8k RPMS, however when I put the car in manual mode it gives the same symptoms at any RPM when it is placed under partial throttle/high load. It then usually backfires upon decel which is causing me to believe more and more it is going rich and clogging the system. It also is throwing engine codes under normal driving (haven't had a chance to pull the codes as work/busy weekend/frustration are setting in).

John Reed is the only person to touch my cars besides myself but he is in North Carolina working on a F430-TT. The Aristo maf was placed inside a intake tube so I thought that could be an issue because the inner diameter might not be exact but I don't have a spare VVTi maf to swap and the USDM GTE maf is not compatible. I know that putting it on a dyno and hooking up a true A/F gauge on it will help and probably reveal some of the issues but does anyone have any other trouble shooting ideas? I sold my perfectly driveable Supra for a car that I can't even take on the freeway. :(
 

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Hi all, I am new to the IS300 scene but definitely not new to Supra's. I recently acquired a 2001 IS300 with a VVTi swap running stock turbos/stock aristo ECU, stock aristo tranny, and a wiring harness from Dr. Tweak.

The previous owner said that it ran perfectly fine at the point of sale however in his earlier posts he complained of the same issue. He said it was "fixed" by replacing a bad throttle body. I am confused because it appears to have the exact same issue but I don't believe the throttle body is the culprit. It only occurs at a higher load/partial throttle boost. It drives fine when I am going on a straight road/no uphills, no boost, lower speed (lower load essentially). I checked the BOV and there are no leaks and it is recirculating.

Example: It is fine at WOT (except for boost cut...which the car wasn't equipped with a boost controller or a BCC....). However when I get around freeway speeds it can't maintain steady speed because the load is higher and it begins to stutter. Almost like it goes rich? The previous owner said the problem only occured around 2-2.8k RPMS, however when I put the car in manual mode it gives the same symptoms at any RPM when it is placed under partial throttle/high load. It then usually backfires upon decel which is causing me to believe more and more it is going rich and clogging the system. It also is throwing engine codes under normal driving (haven't had a chance to pull the codes as work/busy weekend/frustration are setting in).

John Reed is the only person to touch my cars besides myself but he is in North Carolina working on a F430-TT. The Aristo maf was placed inside a intake tube so I thought that could be an issue because the inner diameter might not be exact but I don't have a spare VVTi maf to swap and the USDM GTE maf is not compatible. I know that putting it on a dyno and hooking up a true A/F gauge on it will help and probably reveal some of the issues but does anyone have any other trouble shooting ideas? I sold my perfectly driveable Supra for a car that I can't even take on the freeway. :(
thats sucks man.....but why would you sell a supra to get this car anyway? even with a gte swap i would prefer a supra even if its NA....
 

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I needed a four door for work purposes. They said I needed to get one with my position change and I get a small stipend for it as well. :)
i guess thats cool but i think your crazy im sure they mean to get a 4 door thats reliable not with a gte vvti swapped motor lol either way good luck that would be great to pull it off if you can get it to drive reliably
 

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Discussion Starter · #5 ·
No reason it SHOULDN'T run reliably...it's a basic BPU swap. This isn't a single/E85/Meth/high stall/nitrous sprayed monster.

I daily drove a 02' 402ci Z06 with a 250 shot of nitrous. If things are tuned right there shouldn't be an issue....


Back on topic, k thx bai.
 

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you didn't do your homework did you, hardware is never the issue of a turbo IS, it's the software - always the software. i ahve spent over 6k in electronics just to make the car run properly and to make the stock ecu happy. then it's programming programming programming. it's near impossible to make the stock ecu perfectly happy and very difficult to get the car to run only on an aftermarket EMS
 

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Discussion Starter · #7 ·
^^^ Not to be rude but did you do your homework and read the first part of my thread? I don't have an IS300 ECU I have an Aristo ECU. So in this case I highly doubt it is the software.

As for spending 6k on electronics, yikes! I would have just had John Reed install a MoTEC/ViPEC/AEM.
 

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well i went through 3 different EMS's finally landing on an AEM when it was figured out a few years ago. i have been doing this for the better part of 6 years, it adds up.

just because you used the aristo ecu doesn't make you imune to the IS's electronic gremlins, there are a handful of aristo swap experts on here and i will wait for them to chime in
 

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Discussion Starter · #9 ·
I agree! It does help having the native ECU control the motor though. And that sucks about having to wait for the technology to essentially come to you. One of my best friends is John Reed (JohnReedRacing.com | Tuning | Turbocharging | Supercharging) who is world renowned for tuning, especially Supras/2JZ's, so I am extremely blessed to have him.

I am beginning to think more and more that wtih the mods and the "custom maf tube" that the car may just need some basic A/F tuning. I hope the SAFC can handle it at this point because it would suck to have to purchase an AEM unit at such basic power levels.
 

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I agree! It does help having the native ECU control the motor though. And that sucks about having to wait for the technology to essentially come to you. One of my best friends is John Reed (JohnReedRacing.com | Tuning | Turbocharging | Supercharging) who is world renowned for tuning, especially Supras/2JZ's, so I am extremely blessed to have him.

I am beginning to think more and more that wtih the mods and the "custom maf tube" that the car may just need some basic A/F tuning. I hope the SAFC can handle it at this point because it would suck to have to purchase an AEM unit at such basic power levels.
:) It's Michael from ETS. I just picked up an IS300 as well. I plan doing an NA-T build. Did you have john reed look at it yet? Good luck with the project! I'm looking to do a 6262 NA-T build, i'm trying to figure out the electronics and fuel return right now. I might just run an FMU / SAFC-II and call it a day. Worked great on the SC300.
 

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Discussion Starter · #11 ·
Hey Michael! I will PM you my number as well. John Reed and I spent about 3 hours on PSI's dyno on Saturday. We couldn't "tune" out the issue and it threw a MAF engine code as well. We joked and just said "AEM it and fix it". I have a single manifold and a 6765 so that's the direction I am headed in. :)

:) It's Michael from ETS. I just picked up an IS300 as well. I plan doing an NA-T build. Did you have john reed look at it yet? Good luck with the project! I'm looking to do a 6262 NA-T build, i'm trying to figure out the electronics and fuel return right now. I might just run an FMU / SAFC-II and call it a day. Worked great on the SC300.
 
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