DavidCBY

It happens consistently in 4th gear around 3000 RPM. Also happens in overdrive.
While my foot is on the gas pedal the engine would rev down 100-200 RPM then continue normally. I tried to search google but i cant find the exact results. I read something about the Torque Converter but idk if thats the problem.
FYI - No check engine light. 128,000 miles.
Has this happened to you? Do you know what's going on? Is my engine/trans about to fail?
Is there a more appropriate place in Club Lexus to move this thread?
Please help! Any info is greatly appreciated.

DavidCBY

where else should i post this to increase the chance of getting an answer?

Mr Jokster

iTrader: (8)

I was about to say torque converter. When it goes down to 100, do you feel the car "suck" back? Like when driving a manual say at 60mph and drop it to first and slowly pull out the clutch, you feel the car suck back a little. (bad explanation, but best I can think of ) If so, I had the exact problem and within a week I lost 3rd, 4th and overdrive on my tranny.

Pull out the dip stick and smell the fluid to see if its burnt. Also, see if its black or dark dark brown and rub between your fingers and see if you can feel any small particles.

I've heard our trannys are bullet proof, so doubt its catastrophic. Probably something as simple as changing the fluid. When I had the same symptoms, I changed the fluid and it was fine for a few days, then it started again (fluid was black in just a couple days) but by then, the tranny was toast (not in a GS)

818GS

iTrader: (4)

sounds like a tranny problem like its slipping or it just takes it a long time to shift. take it to a mechanic.

DavidCBY

Not 'to' 100 rpm, at around 3000-4000 rpm, or around 60mph, the rpm would slip down by 100-300 rpm while I'm pressing the gas pedal then proceed to drive as normal. This has been happening for years and I've changed the fluid 3 times since I bought the car 2 years ago. But now its happening too often.

And I wanted to see if someone knew about this problem before I spent 300 at Lexus. Mom and pop mechs can't figure out the problem.

818GS

iTrader: (4)

so the rpms drop but it drives fine?

DavidCBY

without releasing any pressure AT ALL from the gas pedal, the car would rev normally, then when i climb up somewhere between 3000-4000 RPM it would rev down a feww hundred RPM before revving back up like normal. Again i stress that i do not release the throttle at any point.

Is my transmission slipping, or is something causing me to lose massive HP for 2 seconds when i reach that RPM, usually around 60 mph?

ronsmoove

Im having that same problem but i do have a check engine light and it is po715 code which means turbine circuit a malfunction. basically this is a speed control sensor that is mounted on to the tranny. I plan on fixing this myself when the weather changes.

BRAD123

Did you try and shift the car manually? Form gear to gear with constant pressure on the gas pedal?

DavidCBY

yes i use them alot. the L,2,3, and 4 do shift during normal acceleration(constant pressure on the gas pedal), although when i shift there is a 1-2 second delay before it changes gear. its not instant. is it supposed to be? could these two problems be related?

edit: and every so often while during normal acceleration the transmission will kick me a couple of times for no apparent reason.

edit 2: and if you didn't know, i dont have tiptronic.

BRAD123

I don't believe it is supposed to be instantaneous...what do you mean by the tranny "kicks you"?

DavidCBY

shortly after pressing gas the transmission will hesitate, followed by a mild knocking feeling and sound, as if it had "slipped" back into place.

on more thing, the shift **** vibrates a little when driving. that just started last week

Munnerlyn

do any one know how to change po715

vijayn

Hey mate -

So when you put it in manual mode in "4", the problem doesn't occur? It only happens when you put it in "D" mode?
If yes then I would say your transmission shift solenoids are changing the gear from 4th to 5th then back to 4th for some reason. It may be getting wrong signals from a sensor.