cwerlin

Has anyone found a way to fix the problem of hitting the rev limiter? This is killing me, now that I have the 3.76 and the TC, I am hammering the rev limiter all of the time. If I spray, it is alomost wasted because I hit the limter so hard, I have to let off the spray, then let off the throttle, finally shift, yeah, get back in the gas, turn the juice back on....DAMN JUST LOST THE RACE.

If anyone has any ideas, I would love to hear them.

Thanks

Craig

JacobT

Craig,

How about some dubz to slow you down so you won't hit the limiter that bad

DaveGS4

iTrader: (2)

I seem to recall that some of the supercharged GS guys have had to 'learn' to e-shift way before redline to keep from hitting the limiter. SRT is also working on a new tranny ECU to couple with the SC to help solve this very same problem, but not sure when it will be done. Might want to PM some of the SC GS guys to get some tips - think there may have been a thread on this as well.

One other thought (not without cost, of course) that might help is to replace your Supra LSD with the TRD LSD. This will put your gearing back to stock 3.23 - but keep the limited slip - and help keep you away from the rev limiter a little better. May not solve all the problems, but at least it's a start. Your exact issue is one of the reasons I am going with the TRD LSD rather than the Supra LSD.

Good luck - please post on what you do and how it works.

LexCiting

I agree with DaveGS4, you probably should have went with the TRD LSD, instead of the gearing you have now. You either will have to wait for the ECU, or trade your LSD for the TRD one. I had the same problem, and I am using the TRD LSD with a SC. I had to relearn to eshift, and even then I still would hit the rev limiter.

Lee

cwerlin

According to Lexus the E-shift really does nothing to force the upshift, if you are on the floor and you eshift at any rpm, the tranny will still not shift until the standard programming tells it to. I went with the gearing to increase the performance, the TRD LSD relly won;t help out setups much, actually the Torsen Diff is much better for everything except straight line traction.

DaveGS4

iTrader: (2)

Sounds like you already "increased the performance" too much

Have you tried letting off throttle slightly to pop the e-shift? Like LexCiting said, its a bit of re-learning how to do it.

I'll disagree with you on the Supra LSD vs TRD LSD, but that's already in another thread...

cwerlin

I do appreciate all of the help here, sorry to sound negative, but this thing is driving me insane. I won't get into the
Clutch pack diff vs. Torsen vs. Quaife stuff, it is a matter of opinion... I will definitely play some more with the e-shift, but what I found when I tried to lift and shift, is when I step back into it and hit the juice the car sounds like it is trying to downshift again. The supra guys have multiple computer companies who program the rev limiter higher for them, but none of them do computer programs for our cars.

Craig

///MDex

Really? I can get mine to shift before redline when mashed, albeit, it takes a hair longer than I'd like, but I can anticipate that duration and button shift it early. This of course is with me starting in 2, and shifting manually.

whitels

This is my observation with the GS4 e-shift. On WOT, forget the e-shift because the car will upshift on its own programmed point like a pure automatic.

Still don't believe it? Put it in M2 and drive the car to about 35 mph. Then, floor it. Upshift to M3 when the RPM reached 5K with your pedal still on the floor.

Did it upshift? No. It won't upshift to M3 as long as your pedal is on the floor and the RPM is below 6K.

Another experiment: Put it in M3, the drive the car at about 25 mph. Then, floor it. Did it hold it in M3? The answer is no. It will, like any automatic, downshift to a lower gear.

The e-shift is good for downshifting to hold the rev in its power range prior to flooring. The benefit with it is you save some ticks in that you don't loose time when the auto will have to downshift for you. You use this technique when approaching a curve, e-shift to engine brake and into the right gear range, and power out of the curve. No time wasted for the automatic to downshift in the middle of powering out.

From what I've observed. the e-shift will not upshift more than is indicated on the M. And this is the part that will hurt you as you will hit the rev limiter if you don't do a highly precise manual shift. The transmission will also downshift at any point depending on the throttle position and load conditions, regardless of whether you are on M or D.

So for straight acceleration, unless you've figured out something, I'll leave it on D with the ECT on Power.

cwerlin

I must agree WhiteLS, this is how my car acts, if you are on the floor, e-Shift doesnothing to force the upshift. E-shift is nice to hod a gear or force the downshift, but it will not force the upshift.

Craig

///MDex

I think you misunderstood my point. I use Eshift when accelerating at WOT to avoid red lining, or hitting the rev limiter (since I have the 3.76 unit) not to acheive better shifts, but thanks for the tips!

And, no, you are mistaken anout it upshifting automatically. I can bounce off my rev limiter all day long if I want, in any gear. At least, my GS4 will do so.

The only time my Eshift will shift to a higher gear without my input, is when Eshift reads '2' even though its really in 1, and the '1' to '2' shift is automatic, after that, its up to me.

In fact, I use Eshift a lot in stop light races since I can leave it in 3, and it won't upshift, and I can let off the gas and use compression braking, even when at red line RPMs.

HTH

EDIT: I guess my transmission is different that you guys'.

whitels

I agree Dex, if you are on M2 at approximately 65mph. The rev limiter will bounce all day at WOT. It will also happen at M3 at some higher speed, and so on.

However, as an example of what I'm trying to say, if you're tranny is on 2nd gear WOT but have M3 on display, at WOT just approaching 60 mph or about 6K rpm, there will be an automatic upshift to 3rd gear. And this auto upshift at 6000 rpm will happen regardless of whether you e-shifted to M3 at 4500 rpm or 5800 rpm.

Using again the above example, if you're tranny is on 2nd gear WOT but have M2 on display, at WOT just approaching 60 mph or about 6K rpm, there will NOT be an automatic upshift UNTIL you e-shift to M3. If you don't e-shift, you hit the rev limiter. I think we all agree on this. But, if you e-shift early to M3 at 5800 rpm, your trans still will NOT follow your command but wait till the engine hits the preset RPM shift point (6200?). Same situation as in D mode although you are on M mode.

///MDex

Yes, yes, yes. We are clear.

Putting the car in Eshift, then jacking it up to 5, is identical to D.

ATLgs4

Hey Dex, I think you and the other guys are talking about two different situations. Your car uses eshift just like ours. Eshift will hold the gear, like you said. But, just because you upshift via the buttons, the car will NOT always shift to the next gear. i.e. at WOT below redline. It shifts in the same manner as a conventional automatic tranny.

tinygs

I was waiting for you to say that! Under WOT, you can e-shift a 2500rpm's, or 5500rpms's, but the car isnt going to shift until its right at redline(pre-programmed shift point)....
Ive tried it many times a hundred different ways.

Also, ask any SERIUOS drag racer form coast to coast and they will tell you the only dis advantage to the torsion style LSD is in straight lin dragging where traction is the main factor....
This is what has driven the high HP Supra guys towards the TRD LSD.........
In a huge HP car, the torsion style LSD will leave you "chasing the car" so to speak..........