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dannyp84 New Reader
6/7/21 3:10 p.m.

So for the last 4 years my daily driver in the warmer months has been my 2002 is300 sportcross. I bought this car when a friend of mine insisted on buying my old pickup truck, (06 Colorado), and I went down the list of "bucket list" cars I've always wanted to see what I could afford. I love the look of the sportcross so much that I almost would've purchased one on aesthetics alone, but a friend who has owned a sedan for many years has also proved to me that the chassis is stone reliable. Since buying the car in 2017, I've replaced blown coilovers with a new set from BC, swapped the automatic trans out for a 5 speed from a sedan with a Supra flywheel in order to ditch the OEM dual mass unit, added some adjustable control arms up front in order to dial in a little camber, and traded my original 3.9 open diff for a factory torsen 3.7 unit. Overall, I'm fairly pleased with the car, being a wagon it is fairly useful and mostly fun to drive, but my gripes are as follows:

Acceleration seems pretty lazy for a ~ 200hp compact car, especially since going to the 3.7 diff. I might get 3.9 gears again and rebuild the unit so I can retain the torsen but also get a little more enthusiasm from the car around town. I have a manual ECU that I could install, but everyone I've talked to who has done the manual swap had strange issues after swapping the ECU, either with throttle response or some sort of limp mode. Right now my car is on the factory auto ecu, and drives fairly normally thinking it's in park. Maybe I'm leaving some timing on the table running it this way? The wagon is also allegedly almost 200 lbs heavier than the sedan, so that could be playing a part as well.

Throttle response is sort of inconsistent, this could reflect back to the auto ecu, or just be a characteristic of the partial drive by wire system. 

Steering feel and turn-in are both really good, but the car feels nose heavy in a way I don't think I can tune out, but maybe a bigger rear sway bar is a good idea to make things feel more balanced?

The hvac system works normally with the a/c on, but ask it for heat and it only works on the passenger side, the driver side just blows whatever temp the outside air is - blend door issue possible.

The driver seat is basically awful, it feels slightly crooked, has no lumbar adjustment, the bolsters are not aggressive enough to hold someone my size steady without supporting myself via the dead pedal, and the alcantara/suede centers have aged like milk. I'd like to maybe retrofit seats from some other car, but that could be an exercise in frustration.

I assume some GRM members have owned these cars and I'm hoping someone has the cheat sheet to making the already playful chassis really brilliant. My commute to work is 3-4 miles on windy, hilly two lane, and I'd really like to make the best of it. Is it unreasonable to think I could throw a few parts at this car to make it feel comparable to my friend's E46 330ci?


obsolete GRM+ Memberand Reader
6/7/21 3:44 p.m.

Oh man, I've always thought these things are awesome, so I'll just be here to read the suggestions and admire the coolness of this wagon from afar.

Aspen HalfDork
6/7/21 4:12 p.m.

I had a sedan, but always really wanted a sportcross.  Yous looks too low, maybe that is hurting the handling with geometry issues.

Fixing the ac would help with comfort, I thought the hvac was the best I have experienced.  Just set the temp and leave it on auto, done.

The car was not quick with the auto, I would have thought the swap would have cured that.  Maybe you are not getting all the horses.

thashane GRM+ Memberand New Reader
6/8/21 1:00 a.m.

In my experience, most auto ecu's of that era pulled timing very aggressively to prepare for a shift. If you're not WOT near redline, may not make a difference. However I don't have experience with this model, but would assume toyota was consistent with their startegy.

I would unstance it, go back to stock ride height, some Bilsteins, and add boost.

Carbon (Forum Supporter)
Carbon (Forum Supporter) UberDork
6/8/21 7:40 a.m.

My manual swapped sportx ran fantastic. The only issue that I had was the cel for the auto speed signal needed an autometer speed signal generator to rectify. Others have had success without it but it didn't effect performance even without it. I needed it to pass inspection. Cd009 swap, srt turbo setup and haltec made over 500whp, recaro pole positions, with kw v3 coilovers and the full figs catalog in suspension. Awesome car. I sold it during a tough time, really regret that. They're imho some of the best cars ever made. 

dannyp84 New Reader
6/8/21 8:54 a.m.

In reply to Carbon (Forum Supporter) :

By speed signal do you mean for the speedometer? Mine still worked after the swap because I think the speed was being read from the sensors on the hub. I want to stay n/a with this car, I'm not really a fan of turbo stuff in general, more complications, more heat etc. 

thashane I suspected something similar as far as timing, but where the car feels sluggish is between 4-5k rpm usually, if I mat the pedal around 5k it seems to pull nice and hard all the way to fuel cut off, but I also wonder if the ecu is set up to run less timing in park/neutral than in drive. The car is maybe a little low.. the sportcross rides exceptionally high stock, with that stink bug stance that I never liked, I assume they did this to counteract whatever heavy items you put in the rear hatch.

Lsxus New Reader
6/8/21 10:17 a.m.

Get rid of that boat anchor over the front wheels smiley

Mine is a sedan, so have no experience with how the sport x handles. With just coils and figs bushings all around, i'm very happy with the way it handles. Especially on track.

dannyp84 New Reader
6/8/21 10:45 a.m.

In reply to Lsxus :

That actually appears to fit nicely in there.. what transmission did you use?

Lsxus New Reader
6/8/21 10:49 a.m.

In reply to dannyp84 :


hunter47 New Reader
6/8/21 1:51 p.m.

Get it back to stock/close to stock ride height for sure. Are the BCs valved for the springs? Matched shocks/springs make a difference.

A proper alignment makes a world of difference, too. Even on crappy all seasons. I ran factory alignment specs (0 degree camber front, slight front toe in) on one of my cars and thought it turned in well, but I recently got it to -2 degrees camber front, 0 toe front, and the turn in is even better. 

Seat issue can be solved with a Sparco R333 or R600 seat. They're still reclinable/adjustable but have more bolstering than a typical seat. The Corbeau FX1 Pro is also a very nice fixed back seat that isn't super aggressive, I ran it daily at one point in time.

Is there a way to spoof the ECU in "Drive" mode? It might not make a difference but if it's easy to do I think it'd be worth it. 

Stefan (Forum Supporter)
Stefan (Forum Supporter) GRM+ Memberand MegaDork
6/8/21 2:01 p.m.

1UZ swap?

Grab a seat from another IS that fits to fix your driver's seat.  While there, look at HVAC parts to fix the blend door issue.

Verify you don't have vacuum leaks, dirty MAF, bad gas, old plugs/wires/coil packs, etc.  Do a good once over/tune-up to eliminate the obvious little issues that can drive you crazy.

Many HVAC systems run off of vacuum signal and if they leak, they won't work well/oddly and this can also be a source of a vacuum leak for the engine that can cause drivability issues.

If the above is all good, then try the manual ECU to see if there is a difference.  I suspect there might be, but its hard to know for sure.

Rear end ratios make a huge difference in how cars feel/drive.  Sometimes changing the overall tire diameter can help fine tune things as well.

Sounds like some time spent "fine tuning" things will help greatly.

Tom Suddard
Tom Suddard GRM+ Memberand Director of Marketing & Digital Assets
6/8/21 2:22 p.m.

Sounds like you need to spend some time sorting. It's wild how a driving experience can be ruined by 10 little issues that are each "no big deal" on their own.

We just wrote an article explaining how we sorted a Civic Si project:


And I've been going through the process with a Honda Element I just picked up, too:


Aspen HalfDork
6/8/21 2:30 p.m.
hunter47 said:


A proper alignment makes a world of difference, too. Even on crappy all seasons. I ran factory alignment specs (0 degree camber front, slight front toe in) on one of my cars and thought it turned in well, but I recently got it to -2 degrees camber front, 0 toe front, and the turn in is even better

I think you get some severe tire wear in the inner front.  The is300 needs toe in to counter soft bushings.  Plus the extra camber will see more wear.  No doubt that it handles better if you are ok with the tire $$$.

dannyp84 New Reader
6/8/21 2:31 p.m.

In reply to hunter47 :

The BCs were made to order and are valved for the springs, they ride fairly well despite the ride height. I have about -3 degrees camber up front and zero toe, which did improve turn in noticeably.

I don't think the car will start in drive mode, so far I haven't tried starting it then switching the selector from park to drive. I'll take a look at those Sparcos, I tend to shy away from fixed back seats because depending on how deep they are, the lap belt doesn't actually get down to my waist, it just rests on the bolsters.

Stefan, looking for vacuum leaks is probably a good idea. Do you guys use the propane torch method to search out leaks? I'm definitely of the opinion that I just need some subtle tweaks to make the car great, I might sacrifice my highway mpg and go back to the 3.9 ratio diff. 

Also, about a month ago I found a company who claims to "reflash" the factory ecu, where they can convert it to the manual style ecu and adjust fuel and timing tables, but I haven't been able to find their website again and I haven't seen any reviews about their legitimacy. I want to say Speed Academy on youtube used them for an LS430 project. To my knowledge, no one ever successfully messed with Toyota ecu programming the way HP Tuners or EFI Live has been able to get into GM/LS stuff, but things might have changed since I last looked.

hunter47 New Reader
6/8/21 4:23 p.m.

In reply to dannyp84 :

Good that the BCs are valved for the springs and you have a good amount of camber in the front. 

Didn't think about car not starting in Drive, haven't driven an auto for a considerable amount of time in years. 

The Corbeau fixed back has fairly low hip bolsters,  I was able to get the lap belt tight across my waist no problem when I had it in my RSX. YMMV. I really liked the R600 but I didn't see the point in swapping good reclining seats in my RSX to another reclining seat which is why I got the Corbeau FX1 Pro.

In reply to Aspen :

I don't think -2.0 degrees will wear the tires considerably. My alignment settings are not for an IS300, I was just giving anecdotal evidence that -2.0 improved already good turn in on my car and that Mr. dannyp84 here could benefit from it. The car in question has -1.5 to -2.25 degrees of camber OEM in the rear and I haven't noticed any considerable tire wear especially with cross-rotations.


dean1484 GRM+ Memberand MegaDork
6/9/21 6:32 a.m.

Sell it and get an ISF.  Yes you loose the manual but you get such a great car in the ISF. I drove one the other day and it is such a great car. 

Ok reality just happened and your car. I think your gearing is an issue as is the tune. I would get it on a dyno for a base line to see what your torque and hp curves look like along with spark advanc and O2 readings are. Most likely the car has a tune optimized for a torque converter and I can see that not working well for a manual swap. Was there a sport mode with the automatic?  I wonder if the ecu has defaulted in to some sort of partial valet mode or something. 

Then there is basic physics. You have the same weight and the same hp and you put a lower gear in it. Adding a manual trans will not cheat physics and make it faster. In fact if the manual is meant for a higher dif than the manual trans will definitely be slower and the car will feel soggy and non responsive 

dannyp84 New Reader
6/9/21 8:41 a.m.

In reply to dean1484 :

I did some research this morning and allegedly doing the manual swap triggers at least 10 CEL's on the auto ecu, so maybe it's time to finally install my manual ECU that's been sitting on the shelf for ages. The lower gear matches the the manual trans, automatics all got the 3.9 while manuals got the 3.7. When I originally did the swap, I left the 3.9 in the car for about a year, and it was great around town but resulted in 20 mpg on the interstate. I swapped to the 3.7 in order to get a torsen LSD.

An ISF is probably not in my budget, btw. They look like great fun though..


Oh and I finally found the company who re-maps the factory ECU, so this is an option, though I haven't spoken to anyone who's gone this route: https://quantum-auto.com/ols/products/ecu-re-map-service-ecu-re-map-srv

Aspen HalfDork
6/9/21 9:56 a.m.
hunter47 said:


In reply to Aspen :

I don't think -2.0 degrees will wear the tires considerably. My alignment settings are not for an IS300, I was just giving anecdotal evidence that -2.0 improved already good turn in on my car and that Mr. dannyp84 here could benefit from it. The car in question has -1.5 to -2.25 degrees of camber OEM in the rear and I haven't noticed any considerable tire wear especially with cross-rotations.

NP, I was only referring to the is300.  They had a known problem with rapid front tie wear that could be cured with some toe in.  Iirc it was due to soft bushings that caused toe out during straight line travel.  If op has swapped bushings this may not be a problem.  Also the sportx has a staggered set up, so  no rotation unless switched to a square set up.


dannyp84 New Reader
8/2/21 2:51 p.m.

Update: I decided that instead of risking a wiring harness screw up with trying to install a manual ECU, I'd buy the Quantum auto ecu that's plug and play (since it starts out as a factory ecu and they tune it). I installed it last week, and it's really transformed the car: no more mid range lag, better throttle response, a smidge more power throughout the rev range. It feels responsive enough that I no longer feel the need to change the rear end gear ratio, and it's drastically more satisfying to drive.

Now that the engine/tuning are satisfactory, I can figure out what driver seat to swap in so that the car is more comfortable and with more supportive bolsters. I also recently had the car weighed at a truck stop just out of curiosity: 3480 lbs with me in the car and about 7-8 gallons of fuel in the car, with a front to rear balance of 1800 lbs front, 1680 rear. Not awful considering the big iron block straight six hanging out up front. I'm about 145 lbs, so the car alone is roughly 3335 lbs depending on how much fuel I have. My RX-7 is over 1000 lbs lighter, but for a 4 passenger wagon I guess this isn't too terrible. This is my every day driver at least in the warmer months, so I don't really intend to pull weight out of it via removing interior panels or anything, I was just curious as to what it weighed with lighter than stock wheels and the transmission swap.

dannyp84 New Reader
8/3/21 8:46 a.m.

I also repainted the centers of my rear wheels while they were apart to replace to barrels, the original finish was really chalky and faded, we went with a Ford silver that seemed pretty close to the original color used by Panasport. I've wanted these wheels since I was 17 (though I imagined them on an fc RX7) so it's surreal to see them on my daily driver now. Still need to source center caps and I'm hoping to find a nice condition set used, as new ones are priced fairly steep..

Floating Doc (Forum Supporter)
Floating Doc (Forum Supporter) GRM+ Memberand PowerDork
8/3/21 9:06 a.m.

In reply to dannyp84 :

Glad you made the right choice on trying to sort it out. I really didn't see where the swap between the two rear end gears was going to make that much of a difference.

dannyp84 New Reader
8/3/21 12:52 p.m.

In reply to Floating Doc (Forum Supporter) :

Back when it had the 3.9 ratio rear, it felt a lot more responsive around town, but at a fairly noticeable detriment to highway mpg. These cars aren't particularly fuel efficient as it is, but with the 3.9 I was getting 19-20 mpg highway. Now I think I can get it to 23-24.

calteg Dork
8/3/21 1:42 p.m.

The fuel efficiency always bugged me. She had a brand new, bone stock one for a few years and on crappy CA gas, we could never break 20mpg. Given how slow that car was, I really couldn't wrap my head around it. 

dannyp84 New Reader
8/3/21 6:46 p.m.

In reply to calteg :

I don't understand it either, one one hand, a G35 with slightly more displacement makes a lot more power, and a 330ci from the same era makes maybe a few more hp and can crack high 20s on the highway, I just chalk it up to the 2jzge being an old design  

thatsnowinnebago GRM+ Memberand UltraDork
8/3/21 7:28 p.m.

Have you looked into 3d printing new center caps? I think a couple folks here have done that for their own cars. 

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