ClassicLexus

I have been driving my SC a while now and have not really had any problems.

But... every once in a while when I put the petal to the metal one of two things happens.

If I release a bit and then push down again the motor revs really high but does not seem to give any power at all.

Also sometimes when I punch the accelerator it kind of hiccups around 4-50 and there is much less power and then the power comes back into full force again.

What is the problem do you think? Engine? Tranny?

This does not always happen but when it does this is anoying and kind of worries me.

Need a guru to answer.

hellasboy

It's something put into Lexus so that the car shifts smoother. Yeah, i know, it's a pain. There are two ways to get rid of this. Torque Converter and reset your ECU.

To reset your ECU, pull the carpet away from the left side of the driver's footwell, you will find a small black box, take the cover off and pull the ECU-IGNB fuse. put it back in after a half hour and your car will feel like new. You can also disconnect the battery for a half hour to reset the ECU, but you will lose all your radio, steering wheel and seat presets.

I'm not too sure about the torque converter getting rid of lag in the upper RPM's but it does get rid of the lag in the lower RPMs, maybe someone with a TC can answer this question better than I can.

Keith13b

iTrader: (3)

"if I release a bit and then push down again the motor revs really high but does not seem to give any power at all. "

I had the same problem - It was the TC acting up. I dropped in a Swift TC, and all has been good!


Keith

Bean

iTrader: (1)

yup sounds like the torque converter as they said; i had the same problem in my 300zx at one point when my old TC was fried

ClassicLexus

Since this only happens when I slam down the accelerator would this warrant a TC replacement?

SC300T

The low speed hesitation could also be attributed to the inherent bad fuel/timing maps built into the ECU from the factory. On early V-8s, low rpm/high load maps cause the engine to ping and activate the knock sensors which scale back the timing and reduce power. What you need is a way to add fuel during low rpm/high load conditions. During light to around 2/3 throttle, the ECU is in closed loop with the 02 sensors controlling fuel/air mixture. Above around 2/3 throttle, the ECU ignores the 02 signal and defaults to its own maps, which are poorly calibrated at low rpm.

There are several ways to get the car to run better... The best one I know of is to buy an Apexi S-AFC fuel computer to instruct the ECU to add or subtract fuel from the curve under these conditions. The S-AFC costs around $300-$325. The car will run alot better and may even make more top end power if you've got exhaust and intake mods.

Other solutions are:

Split-Second ARC $269
Simple box that Adjusts air/ fuel

Or the TSC1 $82, which fakes the coolant temp signal into thinking the engine is cooler and therefore adding more fuel to the maps.
(won't hurt normal fuel economy in closed loop).

www.splitsec.com

ClassicLexus

Very interesting. Thx.

Do you think the Swift Racing HFI/ECU mod would cure these symptoms?