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Discussion Starter · #1 ·
First off I’d like to thank Kean, Chris and Justin … Boostlogic, Performance Motorsport and Tuning Concepts for a great job

’96 SC300 5sp with a set-up optimized for road racing and goals of ~300rwhp at low boost on pump gas and 400+ on 50/50 race gas with fast spool and a good flat torque curve.

Kean recommended a PT61 p-trim with a .58A/R. We figure a tt head gasket for 9.1:1 compression and a MAP ECU would do the job since I am not looking for maximum power. Add a tt radiator and an oil cooler for heat management as well as a bunch of PM (timing belt, valve stem seals, wires dist. cap et al). I choose an ACT street clutch for derivability, a TRD LSD and 50lb injectors so we would not run out of fuel. Since Justin wanted to adjust the timing we sent the ECU out to be modified and asked them (Techno-square?) to raise the rev limit at the same time. Then I drive the car 1,200 miles to TX and the car goes under the knife.

The tale

Chris works through a bunch of issues (gasket leaks and a warped head) and gets the car put together, Justin tunes it and it makes great numbers --- 325rwhp @ 8psi and 425rwhp @ 16psi. Good solid torque numbers and a very wide power band. Only a couple of problems 1) it leaned out at 16psi boost ; 2) there was something funny at the low end and the plugs would foul; and 3) the car would fuel cut after 3 sec of acceleration (with or without boost).

To make a long story short, and after a whole bunch of calls and testing (95 & 97 ECU’s wouldn’t work, then a loaner ’96 ECU (Will Neely?) told the story). It seems that the fuel cut was caused by the reprogramming, but the other issues seem related to the ’96 ECU. I think Will was working on a car that had a similar problem with running lean at high boost that a FPR couldn’t fix. We also heard stories of others that had similar problems. A Lexus master tech indicated that the ’96 ECU is notorious for having issues. I would guess it is a bit of a patch job to allow a ’96 model with OBDII without thorough engineering since they were moving to VVT in ’97. I’d also heard that the ECU changed during the model year. If the fuel cut could have been fix’ed we should/might have been able to get the MAP ECU to overcome the other issues, but I didn’t trust the ECU reprogrammers and in the end we chucked it and went to an AEM. Everyone was very helpful in working through these issues and getting the car just right and on the road.

The happy ending

315rwhp @ 8psi and 415rwhp @ 12psi! Couldn’t dyno the car at 16psi as the clutch was slipping. Kean estimates it should be close to 500. Not a lot for the drag strip but it should be great for road racing. The car is a dream to drive. Lots of smooth power everywhere, and it seems very linear. The turbo starts to spool at around 1,500rpm and reaches 8psi at around 3,500rpm. Well over 200ft-lbs at 4,000rpm. I can’t wait to get it on a road track. 20.2 mpg before and 16.2-20.5mpg after depending on whether or not I behave and stay out of boost.

Final thoughts

1) Think twice before messing with a ’96 ECU, there could be weird gremlins in the box.
2) Tuned by a pro (or artist), the BL kit with an AEM has lots of power and is very drivable.
3) Go to Boostlogic for great parts, Performance Motorsport for a clean install and Tuning Concepts for a great tune. :thumbup:

Before with ECU & MAP @ 13psi


After ---with AEM @12psi
 

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congrats

congrats on the Na-T setup...wondering if you have any pic of the setup......l8erz
Michael Nguyen
 

· Back in Long Island =)
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nice num,ber can wait to see what she will do on 18lbs boost ;)
 

· MyNuttz
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wow...good to know what kind of troubles to look forward to with my 96....more reason I may go TT...
congrats on the sweet setup, bl and aem...sweet combo
 

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Discussion Starter · #7 ·
Thanks to al for the good wishes

MekoZ, picture below. When it is warmer here in MN I'll pull the belly pan and get some pictures from below and of the IC and oil cooler.

Xdreamer, limited to 16psi (at least on 50/50 race gas) with the tt headgasket.

Blue-3li, we'll see how the tranny holds up road racing. At least no 5,000 rpm drag drops

Ravan17 The tt radiator and oil cooler may be overkill, but road racing puts heat into the engine 30 minutes at a time not 10 sec. It's time at boost not hp

 

· Lord of 10 lbs
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Lookin good

The other car, which Will Neely has been working on is my 96 na-t. We had tryed the map ecu but no go. Now I am going with vpc / safc. Last dyno we ran was 471 dont remember exact psi. Ill get the graph up asap. Still having minor problems, but we hope to have those fixed by next week.
 

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Discussion Starter · #9 ·
Boostin

Thanks for the loan of your ECU. It was critical in pinning down the problem and getting my money back.

Good luck with your car.
 

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Discussion Starter · #11 ·
Thanks Will. and as I said to Boostin, thanks for the loan of the ECU

But I just posted. Kean, Chris and Justin did the work
 

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96sc3 said:
wow, very imformative.... i didn't know 96 ecu has bugs,,,,
Heh Bryan.
In that case you must have thought I don't know what I'm doing and my lean spike + rough idle were just issues I couldn't figure out. :p

The '96 ECU has proven to be a major pain in the ass.
If anyone has an AEM laying around, let me know.

JKAG: Thanks for putting this out here. I've been troubleshooting the problems you described for a few months now and this post gave me the answer I needed.
I wanna ask you about the problem you described as "plug fouling".
Was this a weird missfire at idle that would get worse if you let the car idle and would it eventually start throwing the P0300-P0306 codes?

~Alan
 

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Discussion Starter · #15 ·
Alan

Sorry, but I can't help.

I drove the car for 2 days (about 200 mi) and once it wouldn't start when warm and acted like it was flooded. I also noticed the occasional misfire. Then it went back to the shop.

I noticed rough idle but we didn't try to fix it. Once we understood the problem we just went to the AEM. I don't even know why they pulled the plugs.
 

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Well thanks anyways. :)

I've been running the car as-is for a few months now.
My turbo hits full boost (capped at 5psi for now) at 3500 RPM and between here and 4000RPM is where I have my worst lean spike where AFR hits 15:1
Did a compression test a few days ago and it came out fine...right around 180psi on all cylinders which is not bad for 144K mile engine with 6K boosted miles.
I really can't wait to get an AEM installed.
I want the feel of the Lexus back.
The missfiring idle is embarrasing, and it feels weird when i mash on the throttle at 3K RPM and the car doesn't go anywhere until exactly 4000 RPM where fuel kicks in and the car launches like a rocket.
My friends go "Oh shit, did the turbo just kick in?" and I'm like "No, the turbo kicked in 500RPM ago; what you felt was the fuel kicking in."
Blah.

~Alan
 

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SPORTcoupe said:
Well thanks anyways. :)

I've been running the car as-is for a few months now.
My turbo hits full boost (capped at 5psi for now) at 3500 RPM and between here and 4000RPM is where I have my worst lean spike where AFR hits 15:1
Did a compression test a few days ago and it came out fine...right around 180psi on all cylinders which is not bad for 144K mile engine with 6K boosted miles.
I really can't wait to get an AEM installed.
I want the feel of the Lexus back.
The missfiring idle is embarrasing, and it feels weird when i mash on the throttle at 3K RPM and the car doesn't go anywhere until exactly 4000 RPM where fuel kicks in and the car launches like a rocket.
My friends go "Oh shit, did the turbo just kick in?" and I'm like "No, the turbo kicked in 500RPM ago; what you felt was the fuel kicking in."
Blah.

~Alan
If the 96 ECU is the reason for your problem, wouldnt an easy fix be converting over to an OBD1 ECU? I know kbprice owns a 96 supra with an OBD1 conversion and when I rode in his car the power was very smooth.
 

· Lord of 10 lbs
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Because of this thread... and after talking with JKAG, I have opted to go AEM as well, the 96 ecu has just been to much of a hassel. It seems no matter what you throw at it, it will always screw up. So if you have the money and man power (I know / heard the AEM is a pita to tune) go with the aem or some type of stand alone.

I am stressing out... but Will (mkivpowered) is doing all the work haha so it must be a real pain to him. Cant thank him enough, and thanks JKAG for posting this. I have come to the conclusion 96 ecu should just vanish. :cool:
 
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