04 SE and premium saudi feul

[dreams knight]

hi every one

since i got my 04 se maxima and i fill in 95 octane feul . day by day I feel it become weeker . but yesterday I filled in it 91 octane feul . then I felt it more faster !!! and more power .

can any body explane what is going on ?

FYI my max is imported from USA

[loystock]

Keif halak habibi?

For the Maxima, Premium fuel is RECOMMENDED (but NOT REQUIRED) for maximum performance. That means regular gas is Ok. In the US, Regular gas has octane rating of 87, Mid at 89 and Premium at 91 or higher. Gas with Octane rating of 95 or higher is not common here. Gas is much cheaper in KSA than USA.

Your car should be able to run with regular gas (87). You may or may not feel the difference. Since the car is designed to run better with Premium (91) gas, an 87-rated gas may cause pre-ignition or 'pinging.' The engine management system (ECM et al)) and the Knock Sensor should be able to detect and correct this by retarding ignition timing. But if you don't get any pinging/knocking with regular gas, then there is no need to buy premium gas. If you feel there is not enough power, then you can go for the higher grade fuel.

Most cars in the US are designed to run with regular gas yet some consumers use premium gas in the belief that it is better for their car. It's just a waste of money. Unless it is clearly stated in the car manual or fuel door that Premium fuel is REQUIRED, there is no need for such. However, if the car REQUIRES premium fuel and you use regular, the ECM and KS may not be able to compensate by retarding ignition timing and thus have pre-ignition (combustion due to high pressure/temperature and not due to spark plug firing). If pinging/knocking is allowed to continue for a long time, the engine may be damaged eventually (piston/cylinder/valves). Premium gas is normally required in high performance cars (high compression ratio and super/turbo charged engines). Fuel with higher octane rating is denser (higher energy content) and is harder to ignite. So if the car is optimized to run at 91 fuel grade, using 95 grade or higher will not improve performance and may even make it worse.

For optimum performance/power, the ACTUAL fuel-air combustion must be at TDC (top dead center) of the compression stroke. But it takes some time to ignite the fuel-air mixture so the spark plug must fire ahead of time to get the desired combustion at TDC. If you use a much higher octane gas, since it is harder to ignite, then the actual combustion may occur after TDC, making the engine less efficient (and less powerful).

[dreams knight]

al hamdo lellah shookran

goood informations my friend ........ thanx

from now on I will use 91 feul octane

BTW how do you talk in arabic ???

[loystock]

I was in Jeddah, KSA working as an expat with Saudi Arabian Airlines (SAUDIA), 86-91.