UpSideDown

I'm having an annoying problem with my IS250 from 2012. When I accelerate and come off the gas pedal, the engine rev dips briefly and comes back. It feels like when you tap the brake quickly. This seems happens only before the engine is fully warmed up and in any gear. Anyone know why it does this?

Here is a recording of this strange behaviour

Gville350

iTrader: (10)

Do you feel that the power of the motor is actually dropping along with the rpms when this happens?

triple7is

Im having this exact same problem. The rev dips when i accelerate from a stop light and have to let go of the gas to slow down. I don't have to step on the brake for this to happen. A good example is a scenario where I accelerate from a stop light and doing 40mph and have to let go of the gas to avoid hitting someone cutting me off.

UpSideDown

yes, it feels like a brief engine brake.

edit:
By the way, I tried in S mode, snow mode, ECT power, same thing. It stops doing this when engine it fully warmed.

Rezno

iTrader: (1)

My car does the same thing when its cold during braking only. My guess is it keeps the car at higher revs to warm it up quicker. I doubt its anything to worry about.

UpSideDown

Well, it didn't do this during the first 3 years of owning the car.

Just curious to know if this is a engine issue or transmission issue and how to fix it. I'm planning to keep the car few more years and don't want this gets worse and end up in a costly repair.

UpSideDown

So you are saying that this is a characteristic of the engine/transmission? Whats your comments base on?

Rezno

iTrader: (1)

When I drive my car when the engine is cold, sometimes it won't shift up until you rev it up to 2000 - 2500 RPM per gear, and if you so much as tap the brake pedal, it will downshift immediately. Your comments about the RPM going up and down as you let off the gas pedal are basically all things I've noticed in my car as well. And since you said they only happen when the car is cold, my best guess is the car does that to heat the engine / transmission faster. I could be wrong though. I think the strangest thing is that you said it hasn't done that before.

I'm going to service my car soon anyway, so if it is a problem and this isn't normal I'll as them about it and see.

UpSideDown

Thanks for your clarification. But I think it's the different issues we are talking about. If you watch my video again you see that when I accelerate pass 2000 rpm and let go of the gas, the rpm falls back to around 1500 rpm, which it normal. But then the rpm briefly dips to 1000 rpm and bounce back to 1500 rpm again. And I was in 6th gear. This never happened in the first 3 years I had the car. I bought it brand new.

UpSideDown

Anyone else into mechanics knowledge know what this can be? I will get the car serviced soon and will bring this up with the service guys. But it would be great to hear your thoughts on this too!

Rezno

iTrader: (1)

Yeah my car doesn't do that. It would be normal if you're accelerating, let your foot off the gas, and revs drop to 1000 - 1200 and stay there until you press the gas again, but this is something I probably don't know. Sorry about that.

Just ask your service guys next time you take your car in.

phis250

My 2011 is250 also does this, the same exact thing in the video. I didn't notice it doing it until I had the transmission fluid changed at the Lexus dealer. It only does it when it's cold, and the needle moves so fAst that I wonder if it's just an electrical glitch and the engine is not actually dropping and revving. Please let me know if you find out what is causing this. My car has 60k on it.

UpSideDown

Yeah, that's exactly the same behavior. It does this only when you accelerate carefully within the same gear. I'll bring this up with service manager later when it's time for service. My car is out of warranty, I'm sure they will tell me what's wrong so they can charge me an arm and leg for it.

Gville350

iTrader: (10)

I've done a trickle flush on my own trans and I've got no ill effects from, especially not that. Wish you all luck in figuring this one out; I HATE electrical issues!

Solara350

Canadian Lexus Eh ? damn Canadian 2011 Lexus IS350 AWD here, this happened after awhile till i got the car, bought brand new, probably i bought it in March and it was warm so i didn't notice it, yes in Ontario its kind cold someday and my car does the samething "IF THE CAR IS NOT FULLY WARMED UP" even if the car is warmed when i drive for like 50 meters and stop at the Red Light in gear D + braking, the car wanna lean forward i have to PRESS THE BRAKE PADDLE HARD for like less than 1 minutes until the RPM calm down and then everything back to NORMAL. I did a research on here and there is a post saying the same with 2014+ model IS/GS and they are all Canadian Lexus cars.

I had RPM surging issue lately too but i figured out it was the bad Gas from ESSO, i only use TOP grade gas, back to the topic, so whenever it's really really cold the Lexus RPM acts weird ? i always warm up my car 7-10 mins before i drive in the winter time. Any pro got any solution ?