I don't know if this has been mentioned, but HKS makes a speed limit controller that can disable the factory speed limiter. It says it's universal but I don't know if it's been tested on a TC.
http://www.horsepowerfreaks.com/viewproduct~Scion~TC~~Electronics~Speed_Limiter_Cut_Controllers~.html

Or maybe I'm just a dummy, but I thought it was interesting.

Also, what about reseting the ECU? Just disconnecting the battery cable for a while and pumping brakes. I heard that someone did that and it stopped the fuel from being cut. He said it went from 127 to about 148 (he thinks) at 5900 rpms.

Can someone confirm this? Very interesting "upgrade".

dude unplug the fuse for it................yes its there look through the manuals.

dude unplug the fuse for it................yes its there look through the manuals.

i got excited cause I thought there was a fuse for the rev limiter :(
but yes, there is an ecu fuse

no your right.............i was reading the manual one night before i even bought the tC and there is a fuse for the limiter. its not in the main ecu either............at least i think that what i read. ill look through it again and see if its right. might be for something else but i saw limiter and a fuse for it and thought speed limiter.

Definately check into that.

Does anyone even know yet what color on the ECU the speed sensor wire is? I installed the Apexi RSM-GP on my tC and it has a speed cut defense system built in. Just need to tap the correct wire.

there isn't a TRAC fuse for the speed limiter like there are on older cars like the JZ supra engine. it's programmed into the ECU, the only way around it is a piggyback or reprogrammed ECU, I'm not sure if that will work or not but Scionspeed is working on it and they are very close to a solution.

oh, and the theoretical top speed of gearing on a manual is 139.4mph with stock tires. auto is 163.7mph @ 6247rpms but you would need OVER 340whp to overcome drag to get up to those speeds.... the Scionspeed stage 3 turbo ought to be able to do that... here's a pic I stole from another forum, property of Zoltiz

http://zoltiz.com/cars/tc/images/gearratios1.gif

so autos have a higher top speed than me..... interesting.... bet i still hit my peak before they hit the same speed

^^^that would actually be interesting to see, we all know the the 5 speed has a faster 0-60, but who has the faster 0-140 :eyes: ......or better yet 0-160....oh wait.....you guys cant go that fast. :rofl:

^^^that would actually be interesting to see, we all know the the 5 speed has a faster 0-60, but who has the faster 0-140 :eyes: ......or better yet 0-160....oh wait.....you guys cant go that fast. :rofl:

And neither can you, nor will your auto tC ever be able to. :blah:

^^^that would actually be interesting to see, we all know the the 5 speed has a faster 0-60, but who has the faster 0-140 :eyes: ......or better yet 0-160....oh wait.....you guys cant go that fast. :rofl:

And neither can you, nor will your auto tC ever be able to. :blah:

Why do you say i would never be able to do it, you can do anything with enough money. Ill i need according to the guy is 340 whp, which the other guy with the scion tc running the turbo has already achieved and surpassed. So dont be so quick to say that ill never be able to achieve 160, because it is do-able.

^^^that would actually be interesting to see, we all know the the 5 speed has a faster 0-60, but who has the faster 0-140 :eyes: ......or better yet 0-160....oh wait.....you guys cant go that fast. :rofl:

And neither can you, nor will your auto tC ever be able to. :blah:

Why do you say i would never be able to do it, you can do anything with enough money. Ill i need according to the guy is 340 whp, which the other guy with the scion tc running the turbo has already achieved and surpassed. So dont be so quick to say that ill never be able to achieve 160, because it is do-able.

Yeah. It's do-able.... but how long do you think the syncros in that auto are going to last with 340hp to the wheels?

To be truthful, i have absolutely no idea whatsoever!

anyone figure out how to take off or adjust this rev limiter???

I saw a product advertised on spike tv this weekend... It plugs in like an error-code reader but then you can reprogram parts of your cars computer.

i think they specifically said the top speed.

hrmmm im just tired of running threw 1st and 2nd gear and hitting the limiter.

im used to having my old bmw that i could go ALL the way threw redline. where the TC just hits the line and limiter kicks in...I HATE IT!

Just out of curiousity, WHY are you trying to go past the rev limiter? It's there for a reason, you know. Are you trying to blow your engine? You do realize you are past the optimum shift point in terms of the power curve.

Unless you are doing forged internals or other internal engine mods that could handle an increased redline, you're only causing unnecessary damage to your engine.

^^^ what are the optimum shift points on a 5 speed tC? just curious.

About 6K-6.2K, it should drop you to about 5K-5.5K which is just about at the top of the powerband.

thanks

then why would a 5 speed be any different from a auto.
it would be the same damn thing... i wanna shift where i wanna shift in a race. im not sayin im gonna go out and pin the needle to 8 every time. i just hate how it shuts me down...the engine IS NOT gonna blow if you go over the limiter GET OVER IT!
i didnt buy my TC to just drive it like some old fart or some safety nazi kid. i have upgrades coming and this is one thing i can get outta my way.

some of you people are Awsome and really cool and helpful.

other are just here to make things ruff and condratict EVERYTHING.

ome of you people are Awsome and really cool and helpful.

other are just here to make things ruff and condratict EVERYTHING.

That's the point. If everyone was helpful and didn't challenge, then you'd never learn or really think. But, oho! if someone says no, the natural reaction is to say "why?" and thus you learn!

So the helpful versus the contradictory are all helpful, just not how you'd expect.

then why would a 5 speed be any different from a auto.
it would be the same damn thing... i wanna shift where i wanna shift in a race. im not sayin im gonna go out and pin the needle to 8 every time. i just hate how it shuts me down...the engine IS NOT gonna blow if you go over the limiter GET OVER IT!
i didnt buy my TC to just drive it like some old fart or some safety nazi kid. i have upgrades coming and this is one thing i can get outta my way.

some of you people are Awsome and really cool and helpful.

other are just here to make things ruff and condratict EVERYTHING.

No need to get all testy and what not. I didn't come to flame. If you plan on redoing your internals to raise your redline then so be it, you have a valid arguement. If you're not doing internal work, then there really is no reason you should be wanting to go past redline. No you may not blow your engine initially, but you are doing damage and it does add up. Do you have auto or 5-speed? If you have auto then how are you shifting? If it's 5-speed, shifting past 6.3K rpm's is not good and you're missing your power curve which can give you a slower time not a better one.

I'm not here to lecture you, I'm just giving you and anyone else who might be considering getting rid of the rev limiter because they are trying to get all Fast and Furious and blow the redline of their engine, something to consider. Just don't be coming on to the General Discussion forum saying "I blew my headgasket". One last thing, hitting your powerband at it's optimum point is not being an old fart nor is it being a safety nazi kid, it's just the way you should be shifting to go fastest.

Why the hell would you really need to go over 130MPH?? I took my Celica GT-S to 145MPH and there is really no point. Unless you hit the limiter in the 1/4 mile why take it off there is no point.

what is the redline on the Tc, i hear its around 5900 just want to know, if its around there do you think we are at a disadvantage when it comes to ther vehicles like teh mazda3 or teh celica with a higher redline

what is the redline on the Tc, i hear its around 5900 just want to know, if its around there do you think we are at a disadvantage when it comes to ther vehicles like teh mazda3 or teh celica with a higher redline

The redline is 6.2K and the rev limiter hits at 6.5K. The 5.9K limit you speak of is the speed limiter in 5th gear @127mph. In stock form, the tC wouldn't benefit from having a higher redline since it hits peak power at around 5.8K, anything past that is pointless.

Now say you go turbo or do some other heavy mods that could greatly alter the powerband, then as long as the engine hasn't stopped producing power, the redline could be raised if the necessary internal work was done to support the added strain.

My Apexi computer continuously logs me hitting 6580-6589 rpms whenever I hit the rev limiter. I've cleared the ECU and Apexi computer numerous times and get the same results, so our real rev limit is 6500. The Apexi tach shows identical rpms compared to my stock tach at low-high rpms so I know it's accurate.

On another note though, I still haven't been able to get the speed limit cut to work. This is due to the advanced braking control system that uses the speed sensor. The ECU isn't wired like most ECUs with a regular speed senspor pin, it goes through a second computer first.

Time will tell. We need a Helms manual or a Scion service manual haha..

just to make another comment on shifting past limiter its pointless to shift past ur power band and u could also cause valves to float so why bother

I will really want to get rid of the speed gov when we are finished with our mods plans so will be looking into it;)

as per one post, I do not believe any autos have syncros, none I have ever heard of in my nearly 53 years:)

Rick

just to make another comment on shifting past limiter its pointless to shift past ur power band and u could also cause valves to float so why bother

shifting where your stock rev limiter kicks will not damage anything... they're very conservative with their limitations.

also... power band is something a lot of people don't fully grasp. If you redline then shift, you fall into a point where you're still making decen HP. If you shift right after your peak torque, once the clutch engages your rpms are so much lower that your torque goes down even more than it fell off at the higher rpms.

I could explain it more, as I'm sure some pople know. Basically at the track, max out 1st and 2nd... After that, learn your shift points, so when you shift you're still at optimum torque. It's an average that you're looking for.

I have to pretty much agree. First and second are fairly low geared and you go through them quickly, third is a bit of a jump so it takes longer to pull through and you can deffinately feel the power dropping off at higher RPM's, I shift early into fourth, not real early.

If you really want to go fast, shift 200 RPM or so early from 1st to second but do not lift the throttle, keep it nailed, same to third gear, it will supprise your with how hard it hits(except into second as fairly heavy wheel hop can result, motor mounts will fix that) By shifting slightly early you help keep of the rev limiter.

Rick

thats interesting

shift!

I have to pretty much agree. First and second are fairly low geared and you go through them quickly, third is a bit of a jump so it takes longer to pull through and you can deffinately feel the power dropping off at higher RPM's, I shift early into fourth, not real early.

If you really want to go fast, shift 200 RPM or so early from 1st to second but do not lift the throttle, keep it nailed, same to third gear, it will supprise your with how hard it hits(except into second as fairly heavy wheel hop can result, motor mounts will fix that) By shifting slightly early you help keep of the rev limiter.

Rick

hold on so ur saying to shift while u have the gas pegged down the whole time thru 1st and 2nd :eyebrow:

goodbye, clutch!

What's that smell? :rofl:

After reading this thread its seems to me changing the gearing would be a better thing to do. Yes I wanna go over 126 mph, I chased a Solara and he was cruising way faster then I could.

Some of you guys are embarrasing yourselves;)

Making fun about what you are unaware of, lol!

Anytime you slam gears you are adding more wear on the whole drivetrain but leaving the throttle down if alot easier on the tranny and engine than lifting while slamming gears.

If you are serious about going fast, often, you will need a better clutch anyway, it is an expendable replacement part, the tranny and engine are not. Only bad thing, it is alot of work to install a new one but not costly for us that do all of our own work. Not lifting will not have that more effect on the clutch and if done properly may be easier on it, depends on how well you drive.

On another note: changing gearing will require changing the speedo calibration possibly, I have not determined where the reading is taken from just yet. Either way, the speed governor will still be in effect.

One idea I have is a circuit inline with the speed sensor to the ECU, once a preset value is reached, it limits the pulse count to say a 125MPH reading to the ECU. This would enable you to go faster but without a speedo changing with the velocity of the car past 125. I do not know if it would efffect any other parameter inside the ECU, Toyota has that pretty locked down. Sure wish I could get some schematics of the ECU!!!! I would adjust the rev limiter up a bit and delete the speed gov completely, yesterday:)

For now, the engine does not breath well enough in NA form to need a higher redline, under boost that would change a bit, even without a porting job. Ported would really awaken the top end. I am more concerned with bottom to midrange power, higher RPM would be mainly for not having to shift as often during autocross runs.


Ok, I have work to do, have a good day!
Rick

You shouldn't be slamming gears. . . my brother worked with Jackson Racing (a race school), and you don't slam gears. You should be shifting perfectly, matching revs on downshifts, and lifting off the gas on upshifts. It's not your drivetrain that wears out; it's your clutch.

Want a higher top speed, get a taller wheel profile. . . that changes your final drive.

I have been to Jackson Racing, did not know they had a driving school, the shop is in the LA area, forget which burb, they do auto repairs and SC systems, nothing there said anything about a school, maybe they added it later.

True, slamming gears is not the proper way to shift, when you are road racing, autocrossing, daily driving, etc. I was refering to drag racing which beats the heck out of your whole drivetrain. Then it is better to shift as quickly as possible and that can be considered slamming to most if they have not mastered very fast shifting. Not lifting is better on the upshifts, the gears are spinning at a better rate than if you lift the throttle and the engine does not go up and down a massive rev range while doing so. Best to have a clutch stop as well so you only depress it just far enough. I learned this from a drag car builder with 27 years of experience both in domestic and imports, I think he may have a good idea of what is best;)

Of course a taller TIRE will change your final drive ratio but at the expense of having the worst possible place to have weight on a car moved even further out from the center of where it spins and possibly more weight as well, not a good idea from a pure performance standpoint. Weight is the enemy of all true performance, unsprung weight is the worst culprit, when you move that out to the furthest location you can, you are really taking a performance hit. Why I cannot stand the big wheel "performance" look, it is silly at best. Show cars, ok, I get it to a point, street or race cars, hardly (a few classes of certain types of race cars do benifit but that is mainly a factor of needing massive brakes. Also, larger diameter tires will still upset you Odometer and speedometer readings which needs to be addressed if you went tall enough to make a usefull gearing difference.

When I autocross and road coarse a car, or do some fun canyon runs, I lift when I upshift, do my best to rev match when downshifting, etc. On a tight course I may just pop in the clutch instead of upshifing or bouncing off the rev limiter because I am at a shift point right before a corner, I just jump on the brakes, lift the throttle, slid the clutch in just enough to disengage it then as my speed comes down I rev match and release the clutch. Far faster that shifting twice in such tight confines and less chance of missing a gear and ruining a good run.

But, I sometimes do not lift on the autocross course, if I have a nice straight and can bang a gear and gain a fraction of a second or so, I go for it.

Then again, I am more than willing to take full responsibility for my actions and fix what I break, seldom break anything though, main reason I drive Toyota products:):):)

OK, I really do not intend to come accross as a know it all because I certainly do not. I do know quite a bit and have alot of real world experience as well as have known many with vast knowledge and a history of success. When I do not know the answer I go to them to get it, not repeating something somebody said online or in a misguided magazine article. (There are alot of great writers in the inport industry that do know their stuff, I learn from them as well:)


I get a little impatient with some of the well meaning but misguided advice I have seen on this forum, normally I am very mellow and helpfull, I will go back to who I really am and be nicer:):):)



Rick

ah! Drag racing, then that changes the game! Yeah. . . they don't really care about clutches in the world of professional drag racing. . . did you know that a top fuel clutch only lasts 1 run? They're lucky to get two runs out of em. In fact, it gets so hot in there, that the clutch fuses together with the drivetrain. Haha!

But yeah. . . a street clutch may take it a few times, but in the long run, it may seriously wear out a clutch prematurely.

oh and oops, my bad. . . I'm mixing up my people. . . my brother's was workin with Skip Barber, at Laguna Seca. . . I don't know why I said jackson racing. I was probably reading a magazine.

Now we are getting on the same page:)

Skip Barber I have known about for a very long time.

I am not that much into drag racing, it is fun but I prefer the total overall dynamics of performance, handling, braking, etc. I love it all though and do plan to drag the car some but not alot, just to hard on gear for the short duration of the fun;) It is a nice benchmark of performance and cool to be fast of course!

Those top fuel guys are pretty crazy, same as the guys in little boats with the same engines, even crazier in some ways. I know they tear down everything after every run, Darton makes most of sleaves for the blocks, often they use a new set for every pass! Darton made a custom set for my Matrix:) Unfortunately I was not able to use them, sold out everything to help my disabled buddy, took a break for a couple of years, now getting back into the game but the tC does not need the sleaves, can run stock rods and pistons quite reliably for along time, sweeeetttttt!!!

Rick

what is the redline on the Tc, i hear its around 5900 just want to know, if its around there do you think we are at a disadvantage when it comes to ther vehicles like teh mazda3 or teh celica with a higher redline

the redline is more like 6250. what kind of disadvantage are you talking about? the redline is just there for 2 reasons...1) to prolong the engines life and 2) because youre beyond any useable powerband at that point. and just because another motor can rev higher doesnt mean jack about the power delivery. look at an old pushrod V8...it makes massive power almost instantly in the revs but is pretty much worthless after 4k. it all depends on how your motor is setup to make power.

Has anyone found out how to change the speedo limiter?

Wow this a really old thread brought back from the dead.

http://www.scionlife.com/forums/viewtopic.php?p=2196971#2196971 this thread could possibly help though.

there isn't a TRAC fuse for the speed limiter like there are on older cars like the JZ supra engine. it's programmed into the ECU, the only way around it is a piggyback or reprogrammed ECU, I'm not sure if that will work or not but Scionspeed is working on it and they are very close to a solution.

oh, and the theoretical top speed of gearing on a manual is 139.4mph with stock tires. auto is 163.7mph @ 6247rpms but you would need OVER 340whp to overcome drag to get up to those speeds.... the Scionspeed stage 3 turbo ought to be able to do that... here's a pic I stole from another forum, property of Zoltiz

http://zoltiz.com/cars/tc/images/gearratios1.gif

Just a question here... I'm assuming that the tC E350 is the manual transmission.

Well it says first gear goes to 30, and 2nd goes to 52. My first gear only goes to 24-25 when the gas shuts off, but 2nd gear makes it all the way to 60 when the gas shuts off. The other 3 gears look correct though, anyone else notice this.

I don't know what's up with your car but that's right as far as my experience with my car which is also a manual. You can get slightly over the red line though so I've been to maybe 31-32 in 1st and 54 or so in 2nd.

^^ well i second guessed my self yesterday and retried it. I was wrong a little. My car does go to 30 in first, but i was right when i said it goes to 60 in second.

Hi there all,

Read about the interest in delimiting the speedo...

There are 2 sensors that read speed from your transmission housing. You can see them both below your intake box (I'm assuming this on the auto tC).They're black in color and in the ECU pinout diagram you see it as NC(T)+ and NC(T)- (you need to check the ECM manual). These 2 buddys are the speed pulse signal sensors. Do not confuse them with NE+ and NE-, they are the sensors for crankshaft rotation.

Next, the speed signals generated at the tranny housing are sent to the speedometer housing aka dashboard in 4 pulse per m/s (you need to check the oscilloscope profile in the tC service manual). Dismantle the speedometer housing and check the back, you should see 2 pin ports, A has 24 pins and B has 16 pins (check the service manual or physically, this might be different for the tC since my car is JDM).

A represents INCOMING signals from various engine sensors (includes speed signal) and B represents OUTGOING signals to the ECM (Engine Control Management) unit. (you need to check the tC ECM manual/Toyota tech notes to confirm this)

The processed (outgoing) signal is in turn sent to the ECM. From what I know, if you spliced a product at the ECM point, it ain't gonna work to delimit the speed. As someone mentioned earlier, there are 2 control units that govern speed limit in the car. The speedo housing and ECM are the 2.

The speed signal needs to be clamped or modified AT THE DASHBOARD BACK housing NOT at the ECM unit. The raw signal CANNOT be sent to the ECM through the dashboard housing unit. Period. :tap:

I managed to get a special delimiting unit from a UK company (they do pure auto electronics) which requires you to spliced their box wire to the INCOMING signal at dashboard back and cut off the OUTGOING wire to ECM. Tape up the cut portion and join/solder their box wire to the OUTGOING signal wire that is dangling from the remaining harness which leads to the ECM unit.

I believe the unit replicates the pulse signal and as speed builds up, the 4 pulse gets higher and higher (compressed). The ECM cuts fuel at a factory preset frequency based on the 4 pulse (20/ms). To get around, the replicated signal through the box generates a similar signal but at a different rate which fools the ECM into thinking the speed limit has not been breached since it is being fed the processed signal from the box. I think this is how it works, not too sure.

Our cars are limited to 112mph in Asia. Based on the same gear ratios and sun gear/final drive of 2.740:1, you can reach 163mph. This assumes you are rolling on stock dimension wheels and tires. If you increase wheel/tire size, you have a higher top speed. When 2008 arrives, it is mandatory to be CAN enabled, all ECM/ECT/sensors will be cross-linked and this would be another hurdle for performance tuning. Currently the RX8 and 350Z are CAN BUS protocol based and to get around the speed cut, only HKS has the delimiting device but it costs 7 benjis ($700). Damn, expensive :nails: As usual, no one has been successful in cracking the Toyota program codes, unlike Hondata for Honda/Acura :(

I'm rolling on 275/40-20 on my ride, based on calculation from the gear ratios and final drive, this translates into a top speed of 184mph @ 6250rpm when speed is delimited. Of course you would need the power to push the car to reach this speed and a long stretch of road space as well :P

I hope this would help you guys to look into the right direction and that raamaudio and Dezod can look into this area for US Toyota/Scion owners. With the kind of power you guys are pushing, you ought to beat/own most hi-performance cars on a nice highway race :clap:

Looking forward to more conquests from tC owners :clap:

Wow wonderful write up.