Lexus IS Forum banner
241 - 260 of 264 Posts

·
Registered
Joined
·
808 Posts
Awesome!

I'm curious why the curves get kinda squirrelly after 5750? Also, torque begins to dip at that point, but rises again later. This doesn't sit right with me.

Its not jagged enough to imply loss of valve control. Perhaps there is some further tuning to be done on the manifold air flap or ignition timing?

Either way, Ill bet the car feels pretty nice.
 

·
Registered
2004 Lexus IS300 NA-T
Joined
·
480 Posts
Discussion Starter · #243 ·
Now that the injector size has changed the duty cycle measurement isn't as much of a factor because my FIC6 fuel table is subtracting fuel from every cell. I can add more fuel easily. I had my laptop datalogging off the FIC6 during the dyno pulls so I'll take a look and post something.
 

·
Registered
2004 Lexus IS300 NA-T
Joined
·
480 Posts
Discussion Starter · #244 ·
Awesome!

I'm curious why the curves get kinda squirrelly after 5750? Also, torque begins to dip at that point, but rises again later. This doesn't sit right with me.

Its not jagged enough to imply loss of valve control. Perhaps there is some further tuning to be done on the manifold air flap or ignition timing?

Either way, Ill bet the car feels pretty nice.
I'm not sure about the dip either. I did look at the datalog and I do need to add more fuel above 6k RPM. Here's a snippet of the datalog from the FIC for the 2nd dyno run. Looks ok to me, but I'd like it to be in the high 11s near redline. I have the MAF clamp at 4.3 volts just to see how the car reacts and that seems to be fine. I want to experiment with higher and lower values for the MAF clamp and see the effect.

As it is, It is a joy to drive. Tuning the FIC is pretty simple. I just need to set some time up with a friend to go for a long drive and reset the battery to clear the fuel trims and really dial in the cells on the FIC fuel map while he drives. I've got it reasonably close to what the stock ecu wants to see because all of the smog monitors are set and it would pass obd smog if it were plugged in today. Occasionally I'll get a slow response code for b1s1 and b2s1, but I'll clear the codes and fuel trims and tweak the fuel map and it will stay gone for longer and longer. I just need to keep dialing in the tune and driving more.

Font Rectangle Parallel Slope Pattern
 

·
Registered
2004 Lexus IS300 NA-T
Joined
·
480 Posts
Discussion Starter · #245 ·
Also, I only had like 75% to 85% throttle on the first dyno run. That's why the power is down and maybe the dip was worse. The dyno guy let me use the remote for the dyno so I had my hands full with the snow mode dance and running the dyno. The 2nd run I actually floored it and was nearly 100% throttle. It was high 12s above 6k rpm so I'll add fuel in that area and keep a watch on AFRs.
 

·
Registered
2004 Lexus IS300 NA-T
Joined
·
480 Posts
Discussion Starter · #246 ·
Another update. Yesterday I installed the premium Japan throttle convert kit to give full 1:1 throttle control without stressing the APPS or throttle motor clutch. The throttle pedal feels perfect now. It's not as stiff as when I was using the xcessive throttle lock by itself. I drove around a bit tonight and it's great. I'll post some more driving videos soon. For now here's a video of how the throttle convert kit gets installed.

 

·
Registered
Joined
·
1,472 Posts
That kit is supposed to be pretty good, i was looking at trying to make a my own version 6-7 years back but had to give up with work and home commitments at the time.

The only thing that stopped my buying one was it was a bit pricey at the time and I couldn't justify the expense.
 

·
Registered
2004 Lexus IS300 NA-T
Joined
·
480 Posts
Discussion Starter · #249 ·
Nice video, Alex.

Gotta admit i thought the Xcessive throttle lock felt pretty terrible at first but I totally got used to it.
For me the throttle was too stiff to modulate. I plan to slide the car and I don't want the throttle pedal to feel like an on/off switch. This kit gives a very nice feel over the stock pedal that is almost too soft. I'm really happy with how the car is driving now. The only minor lingering issue that remains is somewhat stiff steering that won't return to center. I've had alignments done before and changed the rack, pump, all ball joints, and both lines, but since I got the car the steering has been overly stiff compared to other IS300s I've driven.
 

·
Registered
Joined
·
1,472 Posts
The only minor lingering issue that remains is somewhat stiff steering that won't return to center. I've had alignments done before and changed the rack, pump, all ball joints, and both lines, but since I got the car the steering has been overly stiff compared to other IS300s I've driven.
My Gita is the same compared to the AS200 i had before, the only difference is this one is lowered and has larger rims. From what i have read it is because the roll center is moved with lowering, apparently RCA would fix it but as i am on springs not coil overs it would raise the height of the front of the car and i wouldnt be able to adjust it back.
 

·
Registered
2004 Lexus IS300 NA-T
Joined
·
480 Posts
Discussion Starter · #251 · (Edited)
My Gita is the same compared to the AS200 i had before, the only difference is this one is lowered and has larger rims. From what i have read it is because the roll center is moved with lowering, apparently RCA would fix it but as i am on springs not coil overs it would raise the height of the front of the car and i wouldnt be able to adjust it back.
I don't think it's to do with the suspension geometry. I'm thinking it has something to do with the pressure in the system or a steering sensor being bad or not calibrated properly. I'm at the point where I'm tempted to take it to my Lexus dealer to have them figure it out. I'm going to plug in my techstream and see if there's any live data on the steering angle that maybe will shed some light on this issue. I really want the steering to be softer because it'll be less taxing to drive on the track. I just signed up for the wet session drift event on January 9th, so I'll be sure to have the car ready for that day.
 

·
Registered
2004 Lexus IS300 NA-T
Joined
·
480 Posts
Discussion Starter · #252 ·
I don't think it's to do with the suspension geometry. I'm thinking it has something to do with the pressure in the system or a steering sensor being bad or not calibrated properly. I'm at the point where I'm tempted to take it to my Lexus dealer to have them figure it out. I'm going to plug in my techstream and see if there's any live data on the steering angle that maybe will shed some light on this issue. I really want the steering to be softer because it'll be less taxing to drive on the track. I just signed up for the wet session drift event on January 9th, so I'll be sure to have the dlcar ready for that day.
I checked the techstream and it doesn't give much data on the steering system. There's live data for the power steering signal and the power steering pressure switch. With the car running, the signal says yes all the time. The pressure switch says no, but when I move the wheel it turns to yes until I stop turning the wheel. I checked the lines to ensure they are on the proper ports. I'm out of ideas. The wheel turns very easily with the front wheels off the ground, so that implies the ball joints are all ok. I've driven IS300s that can turn the steering wheel with one finger at idle. Mine is much more difficult than that. Any other ideas are welcome.
 

·
Registered
2004 Lexus IS300 NA-T
Joined
·
480 Posts
Discussion Starter · #254 ·
Could it be a low idle speed and/or an underdrive pulley situation?
No. It's neither of those. Next time I have the front wheels up I'm going to remove the tie rod ends from the knuckles and move the rack completely side to side with the engine running to see if perhaps there's some trapped air and how the rack feels with everything disconnected.
 

·
Registered
Joined
·
1,472 Posts
I don't think it's to do with the suspension geometry.
why not? I have read quite a few threads on the same thing. All the coilover lowered Altezza boys over here had the same issue, installed RCA (Roll Center Adjuster) and it went away.
 

·
Registered
2004 Lexus IS300 NA-T
Joined
·
480 Posts
Discussion Starter · #256 ·
why not? I have read quite a few threads on the same thing. All the coilover lowered Altezza boys over here had the same issue, installed RCA (Roll Center Adjuster) and it went away.
My car isn't lowered, I have mild angle knuckles that function as RCA'S as well due to thickness. The tie rods are nearly parallel to the ground with the car on the ground.
 

·
Registered
2004 Lexus IS300 NA-T
Joined
·
480 Posts
Discussion Starter · #258 ·
Took the car to the drift event on 1/9/22 and it did great. No issues at all with the car. It ran flawlessly and stayed nice and cool because outside temp was around 50F. I've got to edit some video and it'll be up on my YouTube soon.
 

·
Registered
2004 Lexus IS300 NA-T
Joined
·
480 Posts
Discussion Starter · #259 ·
Here's a video from the event using my Rylo camera. I did several runs and just cut them all together back to back. It was quite slippery out there, even after putting my 265s on the back. I definitely need more practice and also need to get a proper alignment done using the pepboys lifetime alignment service I have on the car.

 
  • Like
Reactions: Hodgdon Extreme

·
Registered
Joined
·
808 Posts
Thanks for sharing. That looks like a lot of fun, even if very challenging for a high power car in slippery conditions. I've never tried it but I'd like to sometime.

When I was younger and dumber - I used to do power-slide sessions in my Miata on the "clovers" where two highways intersect.


 
241 - 260 of 264 Posts
Top