1998 SC400, 1UZ, installed Link Xtreme ECU

[robertcope]

Howdy,

I have a 1998 SC400 that I'm turning into a street/track car. Mods to the engine are fairly simple, PPE headers, some port work on the head, VCIS removed from intake, and now a Link ECU. There is also a R154 swap done. Full build thread here: https://www.trackjunkies.org/topic/6132-1999-lexus-sc400/

Anyhow, thought I'd share my recent dyno results. Had the car tuned by a supposed expert, but to be honest, he doesn't seem to have done much when you compare the before/after ECU configs. I'll be going back and doing some work myself at some point.



I've also attached the ECU config in case anyone is curious or finds it helpful.

Things I'm doing next: get knock sensors working (I thought tuner would do this...), remove MAF from intake path, redo "muffler shop quality" exhaust. After that I'll get it back on the dyno and do some tuning myself.

robert

 

[gloverman]

Ill have a comparison to some of my maps when on my laptop. I just solved an issue on a 1uz in canada that was blowing coils. Cheers

 

[gloverman]

IS your E-throttle working as that map it's turned off. Quite different on the VVti settings. Possibly due to the lack of AVIS. Whats controlling your fan?

 

[robertcope]

IS your E-throttle working as that map it's turned off. Quite different on the VVti settings. Possibly due to the lack of AVIS. Whats controlling your fan?

Ethrottle was working, but failed on the dyno. I had a kit that allowed us to do away with it and just use the cable, so that's what I've done for now... figure it is less things to fail on track.

I am not surprised the VVTI settings are different. Like I said earlier, the tuner didn't seem to do much -- and IMHO, the tune was basically very sloppy, the VVTI settings being a great example. I tried to make the table reasonable based on other tables and Toyota's guidance in the workshop manual... but the tuner just slammed it to 30* and called it a day. I'm willing to bet I find a better setup when I get it back on the dyno.

I have to be completely honest, I am not sure what is controlling the fan. <embarrassed look> I haven't had any issues with the car getting hot, and I'm pretty sure I've seen it running... but I have no idea how now that you ask. I'll have to play with that once I am home again and it is going to drive my crazy thinking about it until then.

 

[robertcope]

On the plus side, I was out of outputs, but getting rid of ethrottle gives me three back... might need one of those for the fan!

 

[robertcope]

It looks like the 1998 SC400 has a dedicated "Cooling Fan ECU". It does have one connection to the ECU, but I can't find anything in the FSM that tells me what that line does; I'm assuming it carries an error signal in the event that the sensor, fan, etc fail. So, I think I'm good on the fan...

 

[gloverman]

I was wondering about that model having a cooling fan ecu. We never got sc400 and late vvti soarer are very uncommon. Do you know what issues the tuner had with the dbw throttle? I didnt see an output for the Throttle motor clutch.

 

[robertcope]

I was wondering about that model having a cooling fan ecu. We never got sc400 and late vvti soarer are very uncommon. Do you know what issues the tuner had with the dbw throttle? I didnt see an output for the Throttle motor clutch.

It just stopped working during a dyno pull. I was watching when it happened. Suddenly we could only get about 30% throttle. I knew that probably meant it was operating by cable only. I did a very quick check of connections and whatnot and it wouldn't come back online. Apparently it worked again the next day as the shop took the car for a drive. But I decided it would be better to do away with it and go to the more simple cable operation for simplicity. Maybe it overheated? I didn't get a lot of chance to diagnose in the moment.

 

[gloverman]

Most common I see is incorrect PID settings. Generally they give fault codes. Cheers.