Angel

05/10/03 - Made lots of progress today ... tuning the AEM on my SC300. ( www.turboforum.net/lexus )

Finally hooked up the Wideband O2 and display, and the GReddy EGT guage.

We were able to get it to idle NICELY with A/F at about 14.5 at idle, however, the idle is still high, we haven't been able to fix that yet ... she idles at 1,350 RPM but very smoothly and happily. We were able to work out all of the throttle response and bucking problems that I was having, the car rides virtually stock now until under boost (of course).

Then ... we decided to have some fun and do some street tuning under full boost. Start out with the car breaking up like CRAZY ... very choppy, running about 9:1 A/F. Started leaning out the fuel so now ... the car runs absolutely smooth from 4K-7K RPM and it RIPS with the A/F at about 11.5:1. I am still getting terrible gas mileage because we havent done any low RPM tuning (so it is running like 10:1 at 2,000-3,000 RPM) ... but besides that I am thoroughly happy.

Also as a side note ... we made all of these changes by using my friends T78 / 850cc Supra Turbo base map. We just modified it to accept the distributor and then had to make some changes here and there to keep her running, but after that, she was good to go.

One more thing that I noted ... my 511rwhp graph at 15psi ... I never got to actually WATCH that on the dyno ... and when we were driving the car around before, she seemed to crack 17psi and hold there pretty steadily. NOW, she rips straight to 14psi and stays there perfectly pinned 14psi (and feels just as strong, if not stronger). I am anxious to see what my graph looks like now.

TRDSupraSE

Angel,

How much do you think it cost so far going with the AEM? Great job on the SC300 so far

Angel

Thanks. Well, I have seen the AEM units going for $1,050 - $1,250 on the SupraForum .. so after that, you need a boost solenoid, IAT sensor, and GM 3 bar map. Then you will need the 3 pigtails for those parts. I bought all of that from gmpartsdirect.com for $174 (I believe) ... after that, you don't NEED anything but some tuning ... however, a wideband O2 kit is a pretty big extra item that is pretty crucial. You don't NEED wideband O2 but it can save you a motor ... wideband kits (including the sensor) run from $500 - $1,000.

I would say that you can be running an AEM system easily for under $1,400 total .. and easily under $2,000 total if you get wideband.

*edit* forgot to mention of course ... if you get low impedance injectors, you will need resistor pack(s). I paid $15 for 3 used DSM resistor packs and wired it all up (see my FAQ - www.turboforum.net/lexus). You can also use Supra TT resistor packs, but I believe they are closer to $150-$200.

SC300T

Great news Angel... I agree with what you said, the AEM seems wonderful when hooked up properly. I'd consider a wideband 02 essential, though---unless you have unlimited dyno time at a very competent shop. Without a wideband, you'd be chewing up a lot of dyno time and it would end up being more than a wideband would cost.

Hopefully I can get my wideband installed next week or so. You've prompted me to put a .81 exhaust a/r on my short list.

Can/will you share the AEM file when you get it running right?
please
please
please
please
please
please

Angel

Sure ... I would be happy to share my map. The car runs fine now ... just having trouble with the idle. I really think it HAS to do something with the idle control valve .. maybe they are just different between the Supra TT and NA ? I know it is functioning because of certain changes we make, so I am not going to replace it, I just need to figure out what is so different that makes the car not want to idle lower than 1,350 RPM.

j0hnyboi

On the Lexus sc300 turbocharged na.. , is it possible to use something else cheaper other than the aem your're using? There must be a simple unit that's plug and play to trick the na ecu from detecting boost. Remember me Angel? singyau78@yahoo.com? I've emailed you several questions regarding turbocharging my sc300 1992. I pretty much have everything, and will start the turboing process this comming Sunday. The last bit of the install is the boosting situation. Obviously to everyone, once ecu detects boost, it'll shut off the engine. LIke I stated earlier, I'm looking for 350rwhp-400 max because of my auto gear box, what simple unit can i use to besides aem to set the ecu to detecting no increase in boost? I've heard about the supra mkiv tt 2jz-gte boost cut defender, which simply plugs into some plug in the vehicle. There doesn't seem to be tunning involved? Can you explain to me what a boost controller can do? What the difference between boost controller unit, and boost cut defender. There are boost controllers for example hks on ebay auctions. Can those units actually prevent ecu's from detecting boost? thanks again Angel. You've been very helpful.

Ebanks

I am not trying to be rude at all, but if you have as many questions about this stuff as you just posted I would NOT be turboing an SC300 if I were you.

Please don't take this as rudeness, I am just trying to save you some money and time... Read up more before you take the plunge!

-Ethan

Lex Luthor

Let me get you started on the right path jonny. What you're referring to is fuel cut, it's in the programming of factory turbocharged cars such as the Supra TT and MR2 Turbo. What it does is cut the supply of fuel once you reach a certain boost level, to keep you from boosting some more. It doesn't shut down the engine as you said, but cutting fuel while under boost is a major no-no, and can/will cause the motor to run lean (too much air in relation to fuel in the combustion chambers).....which can cause it to 'permanently' shut down, if you know what I mean. GReddy calls theirs a BCC (Boost Cut Controller), HKS calls theirs an FCD (Fuel Cut Defenser), these are simple devices and can be made @ home, not that I recommend that. Long story short, you're talking about an SC, which is not turbocharged from the factory and therefore has no fuel cut, so there's nothing to 'fool'. What you will need is a way to add supplement fuel since you will be ingesting more air into the motor (via the turbo), and a way to lower compression and retard ignition timing if you plan on running past 10-12psi. Now start reading and don't touch that car until you feel you know how everything will work.

- LL

awj

Great work Angel. Glad to hear it.

Lextreme

About low impedance injectors. You can also get Radio Shack resistors for $1.00 for 2 (total $3.00) and it would work too. I am running MKIII Supra 440 cc/min in my LS400

Angel

LOL, this thread is over 4 months old now. Lots has happened since then.

Bean

iTrader: (1)

lol

i need some 440cc injectors...

awj

D'oh....

didn't recognize. nevermind.

Lextreme

Bean,

Get them from Ebay and i know a place where you can get them clean and balance for cheap...

wmulli

Could you post where and how much? Do they blueprint them or just give them a cleaning?

Thanx!