Lexus 400h running rough and steering loose

robl · January 3, 2023

Hi all! My local garages are too busy to take a look at the car until next week so just wondered if anyone on here had any advice in the meantime. My Lexus 400h is feeling rough with various symptoms:
Fuel economy down 20%
Engine sometimes feels rough under acceleration, particularly in the low end between 15-40mph. This is intermittent, somedays it feels great and really fast.
Steering feels looser - have to turn more to adjust direction etc etc.
Steering was creaking a lot the other day when I was parallel parking (i.e, lots of full lock to full lock turns). Never heard this before.
I'm feeling more road vibrations through the steering wheel and accelerator pedal and more engine vibrations also.

I did a ISC reset on the car last week which made it feel much better for a few days and brought back lots of engine power. However, unfortunately it hasn't lasted very long and car is feeling rough again. I've tried doing an ISC reset again and it didn't do much a 2nd time around.

If anyone has any tips or advice whilst I wait for a garage to take a proper look i'd be v grateful! I have a fair bit of driving to do this week so just wondering if I can do anything to help myself in the meantime. Cheers and happy new year all. Rob

PCM · January 3, 2023

I think I'd avoid driving it...

Have you tried Japex in Kings Langley for advice?

https://www.japex.co.uk/contact/

robl · January 3, 2023

Thanks for reply. Yes I was wondering whether best to avoid driving it. I haven't tried or heard about Japex, i'll give them a call now.

Bluemarlin · January 3, 2023

Pretty hard to diagnose from a distance, so all I can refer to is my own experience of a previous car running rough, partcularly in the low end. I replaced the air filter, cleaned the MAF sensor and throttle body and it ran great after that.

As for loose steering issues, my guess would be worn suspension components.

robl · January 3, 2023

Thanks Bill! Air filter is looking ok. Will try cleaning MAF and throttle body.

#Sandy# · January 3, 2023

It may be worthwhile pulling the spark plugs to check their condition keeping them in order will define which cylinder may be suspect.

In respect of the steering I am unaware whether it is electric or hydraulic. If hydraulic check the level and turn full lock left and right a few times to ensure there is no airlocks. Air filters can look ok,if in doubt change it .Best of luck.