Hi,

Just wanna share some learning.

I have a IS250 with 77km (47k miles) on the clock, model 2013.

It started to:
- jerk a bit when I was cruising around 60-80km/h (30-50mph)
- use +20-30% more petrol (12,5-13l/100. Normally I do 9,5-10,5)
- be slow in accelerations (even slower than they normally are...).

I had no fault codes, couldn't read any misfires and I was unsure if the lack of acceleration was slipping gears or what.

No misfire reads and reading about these symptoms online, made me doubt if it was a torque converter, or "just" an ignition problem.

I did following first:

- Cleaned the MAF sensor
- Cleaned the throttle body
- Changed 6 x spark plugs (cylinder 3 had some corrosion on the bolt part, but part in the engine was fine)
- Changed 6 x ignition coil
- Changed intake manifold gaskets
- Checked PVC valve (ordered one hadn't arrived - it was fine...). Also, I didn't see much carbon build-up under or in the intake manifold.

This fixed the problem. So learning for me was that the symptoms for torque converter and a weak ignition are somewhat the same. I believe my problem was a weak ignition coil - or more coils. I noticed it didn't have Denso sparks, so these had been changed before. Now it has Denso...
I know I didn't have to change all six coils, but the car is 11 years old, so did it as a service and to feel safer.

Hope it's useful,
Steven