CASANOVA86

Hey there fellow SC enthusiasts I finally got my SC300 on the road after having it for a year & a half, it was automatic but I converted to stick. But now I've been driving it for a couple of days & I've noticed that the car is running at really high revs. It does 60 MPH @ 4,000 RPM's I hope that's not normal it feels like it has a higher gear ratio like 4:10's or something it also lags like 2-3 seconds on 2nd & 3rd gear when I floor it & when I turn it on when its cold the MPH needle starts jumping a lil bit for a few seconds until I drive off WTF!, it feels like it starts getting power around like 2000-3000 RPM's like if the first 2 RPM's are pointless. Would this have to do anything with having 19" rims/Auto ECU/Auto diff/Stage 3 clutch, IDK please if you have any info please let me know I would really appreciate it.

imDementeD

iTrader: (7)

auto diff..
the stock gearing is a 4.27

Sup2jzgte

i have pretty much the exact same issue except my transmission is auto, but everything you listed is the same. i wonder if its something with the ecu's, but honestly i dont know

imDementeD

iTrader: (7)

^ ur issue sounds like its not going into OD since you have an auto
is ur O/D off light blinking at all..

mine did this before and its an issue with the ecu but..i had to turn my od off(off) then once i got to about 3-4k rpm turn it on and it'd shift into 4th(od)

1WILLY1

iTrader: (9)

no the problem you have here is typical of doing manual swaps----your rpm gauge is for an automatic but you need to swap it for a manual --i have seen other people with this same problem and have seen people give them the same answer------like u said it feels like your getting power at 2 or 3000 rpm's? thats cause your gauge is off not your engine or anything important---u can probably drive like that and just dont rely on the gauge for gear chaging--use your ears and feel------good luck and keep us posted.

imDementeD

iTrader: (7)

^ didnt think about that...however i did assume people could tell if there car wasnt really at 4k by hearing/feeling it.

Sup2jzgte

Nope OD light works and has never flashed at all.

imDementeD

iTrader: (7)

well still try what i suggested and report back..i had two issues with my tranny at the same time..one may be the reason it blinks(solenoid is going out) the other might not of thrown a code and was the one that was ecu related and not allowing the car to shift into OD..just give it a shot ..or try swapping an ecu with a known working one from a friend if you know anyone close with an sc

CASANOVA86

Well that's the thing it does sound like it's around 4000 RPM's & my O/D light flashes on/off even though I'm stick now I'm assuming it's because of the auto ecu.

Subjug4tor

iTrader: (1)

The transmission swap won't affect what the tachometer is reading, it reads off of the ignitor, not the transmission... You're thinking of people that do 1j swaps and then have a messed up tach. Your problem (at least with the RPMs) is the Diff.

cartmill

iTrader: (3)

there is all kinds of WEIRD and MISINFORMATION in this thread.

#1 only your speedo should be wrong, unless you have an sc400 cluster, in which case the speedo would read low and the tach would read high.

#2 your problem is not the diff. a 92-97 sc300 w/ automatic trans had a 3.92 differential. this is ~4% LOWER than the 5spd 4.08 diff. if the diff ratio is lower, you will travel farther with the same number of driveshaft revolutions. this would make you cruise at a LOWER RPM at the same speed, not higher.
your new 5spd trans and speed sensor is outputting the speed signal for a 4.08 final drive, which is ~4% higher than what your speedo had previously been seeing.
SO, your speed is probably reading ~4% low.

#3 if your cluster and tach is jumping all around with lights blinking, you probably need a new cluster. your tach has nothing to do with the transmission. it gets the signal straight from the igniter "TACH OUTPUT" wire on the igniter. (as the guy above posted^)

could your cluster be out of an sc400?
the sc400 tach is made to take 4 ignition shots from the v8 instead of 6 from the 2jz (this would make it read 1/3rd HIGH) somebody correct me if i'm wrong here, but i'm pretty sure that's right. of course this would only be correct if your cluster had been reading high since you owned the car, and not right after you did the 5spd swap...

i did a 1jzvvti swap into my SC400 and i have this problem because i have a sc400 cluster... so my speedo reads 4% low because of the lower final drive, and the tach reads 33% high because it's for the v8

see if you can get an sc300 cluster to swap in. and even better, try to get a 5spd cluster

stockhatch

iTrader: (12)

The auto sc300 had a 4.26 or 4.27 diff. Can't remember exactly, but it is a lower gear than the sticks had. You have it backwards, 3.92 is a higher gear than 4.10, not lower. Lower gear means speedo reads higher than normal, not lower.

cartmill

iTrader: (3)

you actually have it backwards.
don't confuse people

http://www.intellexual.net/faq.html
scroll down to the gear ratios section for the final drive.

stockhatch

iTrader: (12)

First time I have seen those numbers. I have always heard 4.27/4.08 depending on auto or manual for the SC300.

From Lextreme's forum
1993-1998 Supra TT manual - 3.133 (torsen)
1998+ Lexus V8 Cars VVTi - 3.266 (open differential only)
1990-1997 LS400 - 3.62 (open differential only)
1993-1996 Supra TT auto - 3.769 (torsen, 3.77 not the usual 3.76 quoted)
1997-1998 Supra TT auto - 3.769 (open standard, torsen available)
1992-1997 Lexus SC400 - 3.912 (open differential only)
1992-1998 Lexus SC300 manual - 4.08 (open differential only)
1997-1998 Supra non turbo - 4.08 (open standard, limited slip available)
1992-2000 Lexus SC300 automatic - 4.272 (open differential only)
1993-1996 Supra non turbo - 4.272 (open standard, limited slip available)

I guess we have conflicting info. Either way, a lower final drive gear(numerically higher) will make the speedo read HIGHER than stock if everything else stays the same.

stockhatch

iTrader: (12)

To help people remember that higher numerical ratios are referred to as lower gears, just refer to the shifter on an automatic car. The lower gear (L) is numerically highest in ratio.