So this week started off on Tuesday with a check engine light. Ah great!...... haven't had a check engine light for past 2 years.

So dug the reader out and pulled the codes - Knock sensor circuit malfunction - both banks, and VVT camshaft sensor bank 2/unable to control knock. It's very sudden and very strange to go from no codes to 3 codes.

The LS was driving super sluggish. Also noticed quite rattly sounds coming from the engine (pinging perhaps?) when accelerating.. At anything more than very light throttle the codes come back.

Working backwards, Sunday evening we had filled our car up and driven home about 60miles/100kms after the fill. No issues at all at that point in time. The car then sat between Sunday evening until Tuesday morning.
About 5 minutes after starting(about the time it takes for the engine to approach operating temp) the check engine light appeared.

Other data details... About the time the codes trigger, the ignition timing is being severely retarded - often by as much as -10 degrees and the O2 sensors look to be oscillating normally throughout, The LTFT's have moved from negative 5 to positive 5.

By yesterday, Thursday evening we had managed to drive through about 2/3rds of a tank of fuel so put in some Lucas upper cylinder fuel treatment and filled up the tank with 57 litres of 95 octane.

Result as of this morning (Friday), the car is now driving much much better, although sometimes it feels as though it is surging. I guess as pockets of good fuel come through the computer advances the timing again, although any heavy application of throttle will reliably bring back the sluggish feeling and trigger the codes.
Driven moderately the car can go several km's before triggering the light and the car is almost as quick as normal until the sluggish thing kicks back in.


So in summary

Has anyone else had this combination of codes and symptoms? Was it bad fuel, bad gas bad petrol?
It's been raining a lot here in the last 6 -8 weeks so it seems possible that some water could have tainted the fuel.

My current plan is to drive this tankfull down until it's close to empty and then replenish with a full tank of 95 or 98.

 

Do you use 5w30 oil as recommended by the manufacturer?

 

10w-40.

5w-30 is too light for our ambient air temps according to the owner manual. The dealerships here use 10w-30

 

Isn't the first number "10W" the cold start viscosity and the second number "-30* the operating temperature viscosity??

 

Another member "Striker" experimented using OW-40 and believe the VVTi system did not respond too well.

The second number "-40" is engine operating temperature rated viscosity.

Operating temperature is controlled by the cooling system, so whether in Alaska or Saudia Arabia, the thermostat should maintain a constant temperature.

Probably you should be using full synthetic 5W-30.

Substitute out the 10W-40.

 

Here are the oil specifications printed in our manual by Lexus. I'm fairly confident the engineers would have spent ages deciding on what gets printed.

Given our ambient air ranges from around 5 degrees Celsius on a cold morning in winter up to 50 degrees Celsius on a hot afternoon in summer (we are in summer now) which oil would you pick from these 4 options?

 

I dont think you are using the wrong oil, but I might be.lol