need to change VVT-i time of 2ZR

[a77ms25]

hi every body

i have corolla 09 LE 1.8 and in few days ago i noticed there is a knocking sound coming from the engine appears only when the engine is warm and when i went to toyota dealer they tolled me its normal "when car starts cold the ECM generate spark in retard position to warm up the engine and when the engine is warm enough the ECM change the spark time to advance position and that + bad fuel type whats generating the knocking sound"

my quastion is there any way or modification i can make to change the vvt cam sensore position to keep the signal in retarded case

[LeanBurn]

What is the octane rating of the fuel you are currently using?

[a77ms25]

its very bad fuel (the only type available) i think 85 or less. i also tryied to use some octane booster but they all useless

[John Mo]

Does it sound like this: Engine rattle on startup

My thread about the noise I have: Engine rattle on startup

[thestone11]

I think our car is designed to run on min 87 octane, the sound you are hearing is more likely to be engine pinging....

[a77ms25]

John Mo no the sound is diffrent it happen during rapid acceleration and the engine is warm (same sound of having a bad old spark plug in the car)

[nate89]

Better fuel is your first step. Try that and see what happens.