does VVTi mean

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higher lift translates to more hp. However larger chance of detonation. If your knock sensor reads knock it lowers your timing and your power. On obd2 vehicles there are products that let you see your timing advance. I would see if your timing is the same with regular fuel or higher grade fuel. If there is a change then you are giving up a slight bit of performance.
 

crinkles

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reason i ask is, I know my 2az-fe does not use anything more than regular, but it sure as [censored] "runs smoother" with premium. but it does not say in the book that higher octane would give higher performance, unlike for some other toyota engines. scanguage II does not work with australian built camry's as Toyota australia has made the car so that only toyota garages can read. for this reason i probably won't buy another again.
 
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Since you are in Australia, you probably have a 'warm' climate. The engine's tune is aggressive. When using the lower octane fuel, you are probably giving the knock sensor a workout. I've noticed this with my Camry 2.4l. Run great on econo-fuel all winter long. As soon as it warms up, have to step up to mid grade. You don't need the book to tell you what to do. Don't confuse 'cam timing' with ignition spark timing. In the old days, we would install a cam straight up and hope for the best. Since manufacturing clearances were imperfect, we then could install the cam with a slotted/keyed pulley/gear and adjust it either retarded or advanced, to make sure it was accurately 'straight up'. And, some adjusted it for power. You could install the cam, then either retard/advance it for more torque down low or more HP higher up in the rpm band. We couldn't have both. VVTi adjusts that 'slot' on the fly using oil pressure and gives us both. The amount of cam phase is growing. Earlier systems were only several degrees and hit or miss(fixed point). Eventually we will see accurate 'electronic' servo control with major angle cam adjusting, along with broader 'variables' tuned for the rpm/throttle position. The 2azfe's VVTi is intake cam only with 40 degrees of cam adjustment(that's a big slot), ECU controlled by using oil pressure. Some automakers eliminated EGR by adjusting the exhaust cam for reversion in place of controlling the EGR valve. So, we have engines with either intake cam adjustment, exhaust cam adjustment, or both. Adjusting the cams will make more power everywhere and improve emissions. If your power loss is noticeable with temperature, you should inspect your cooling system. Make sure radiator has nothing blocking it. Test the thermostat and make sure e-fans are cycling as required. You could also do some 'cooling' mods like bypassing the TB coolant, installing a cold air intake, a bigger radiator, or insulate wrapping the exhaust. Also vary the gas stations to rule out low quality gas.
 

crinkles

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thanks unDummy. so that means use of premium is probably good for the engine in terms of smoothness and durability as the knock sensor wouldn't be working to hard?
 
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Just use regular like your owner's manual states. I have an 08 xb with the 2az-fe, using a full tank of premium was a waste of money. It made no difference over regular (except make my wallet lighter).
 

crinkles

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but it really seems to run better on premium... no kidding... it is noticeable. upon startup the rev increase the ECU does is a lot lower too than it would be using regular.
 

crinkles

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Thanks for the link. the 2az-fe is a low compression engine. the manual recommends regular. this makes sense. yet it runs better on premium. this does not make sense. so either our regular grade is not up to scratch or toyota builds in a knock sensor and tells people to use regular so people see the car as cheap to run. leading to more sales. ---confused---
 
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 Originally Posted By: crinkles
but it really seems to run better on premium... no kidding... it is noticeable. upon startup the rev increase the ECU does is a lot lower too than it would be using regular.
You are right, toyota engine control unit have multiple iginition map that will optimize the ignition when it does not detect the knocking.
 
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