lucidio

Not sure where to begin, but basically I have bought a IS250 a year ago and it had transmission problems, that was solved (I assume) by transmission mechanic. Everything was fine for some time, but after few months my car went into a "limp mode" one time and it never been the same after that.

It drives perfectly, until engine cooling fan kicks in and starts to heat up. I've been to mechanics and they've said that mechanically transmission is fine, and fan does it's job. But weird things start to happen when its hot. Acceleration starts to be laggy or too responsive, like something is going on with computer or smth. Also, when it happens, car always shuts it's engine off imidietelly I go from reverse to drive.

I don't get it, why it happens on the hot engine (or transmission). Anyone have a clue?

primavera

I don't know what was done and what fluid was pumped in but it seems like the transmission fluid level may not be correct.
Lot of mechanics don't have a clue how to service sealed transmissions.

https://www.clublexus.com/forums/is-...ler-is350.html

lucidio

That makes sense. I will investigate this. Thanks for the tip!

2013FSport

iTrader: (2)

We need some details about pending OBD codes, and if in limp mode, actual codes.

Being a 250 the sluggish acceleration could easily be carbon build up on the intake valves.

So, with foot on the brake, engine warm, you put it in drive and continues to idle. However, if pulled from park to reverse it dies? Is that correct?
Or there are some who use the transmission as a brake when going forward and drop it into reverse. This action depending on the speed and RPM can kill the engine and is not recommended.

How many miles on it? When were the spark plugs changed? And how is it used? Is it doing a bunch of short trips?

lucidio

I don't have codes, since I've did a reset that time when it went limp without checking the codes. And it never went to limp mode again. ​​​​​​

Carbon buildup was my first guess but it was checked recently.

About stalling, not exactly. If you put from park to reverse it is all good. It stalls only in specific situation - when you go from Drive to Reverse and then to Drive. Or just from Reverse to Drive. I'm the only driver of the car and would never use transmission as a brake. It even sounds painful to hear that someone would do this. Everytime I change drive mode, I make sure car is fully stopped.

I did not change spark plugs since I bought the car, which was a year ago. It has 220k kilometers (136k miles). On short trips it drives like perfectly. Unless I drive trough city where are lots of traffic lights, jams, etc.

2013FSport

iTrader: (2)

My former spouse was good at it. Let me back in here, I'll just move this lever from the forward gear position to the rewind position? Lol
Bigger engines and trans back in the day but....

Have you had the battery and alternator tested? Cooling fans could be dropping voltage, perhaps start there.

If you don't know the plug condition, I would change them and have someone verify the carbon situation.