I think it's to do with the fuel. I re-filled with 95 octane, it seems that the engine generates more heat when using 95 octane. I have to turn on the heater, set at 27degC or above, fan speed at no. 1, then the rattling noise goes away. but as soon as the heater is off, the noise comes back. I then re-filled with 91 octane, the noise dissapeared. but after about a month using 91 octane, the rattling noise comes back. I really dont know why, may be I have to re-fill with different brand of fuel. I have always use Caltex, may be too good, I will try some other brand.
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91 or 95 octane is suitable for 9.5-10.5 ratios ( most engines)
for 12.9 you will find that it runs best on 98 octane
it may be good on 95 octane but generally the higher the compression ratio the higher octane rating
discuss the octane rating required with the bike service agent/service center
I assume it is a petrol engine !! I found a listing which says it requires premium ULP, not E10 or E20, so I think it does not like that much ethanol. Fill up as much as you can with 95 or 98 octane and see if it improves. It may take a few miles for the fuel to mix and the computer to relearn the new octane it will now drink.
95 octane is the only fuel available here in spain so if your not sure use the higher grade as 91 octane is what we used to use for very low compression engines like truck engines when i was young ,these low compression long stroke engines were used a lot in bygone years before the advent of the introduction of diesels in the late 60s
Higher octane fuels are used because they are more stable than lower octane fuel.
Low octane fuel is more likely to pre-detenate at high engine temps
Your cx7 has a high compression engine, meaning it compresses the air probably 10.5 to 11.5 times. This generates a lot of heat. Using a lower octane fuel will likely ignite before the engine has completed it up word compression stroke.
I would not advise using a low octane fuel. You can however use the mid octane fuel and you should be fine. Test it out. If it is hotter then 85 degree out constantly i would suggest not using the mid octane fuel
SOUNDS LIKE MAYBE FUEL FILTER NEEDS REPLACE, AND OR EVEN SPARK PLUGS AND WIRES. A GOOD TUNE UP. IF YOU RUN LOW OCTANE FUEL YOU MAY TRY A CAN OF OCTANE BOOST, OBTAINED THRU THGE LOCAL PARTS STORE, IN WITH THE NEXT FILL UP. IT WOULD PROB BE A GOOD IDEA TO GET SOME INJECTOR CLEANER AND PUT IT IN WITH YOUR GAS TO SEE IF THAT HELPS.
Different octane fuel should have no real or lasting effect on your car except perhaps a bit of slight detonation. (computer will normally compensate for this by retarding timing a bit. Since you added higher octane fuel, the mix should be slightly higher than in the beginning. To improve octane of remaining fuel you could add 3oz of acetone to each 10 gallons of remaining fuel, or drive it and keep adding 93 every time you use up a quarter tank. I think that you may not be having a problem with the fuel itself but may have an improperly sealing fuel cap. That would turn the light on.
Use higher octane gas for a few tanks, The recent addition of ethanol can lead to moisture build up in your fuel system. Try 89 octane or higher or 5 gallons of premium the fill with regular, and try filling up at night when temperatures are cooler.
The best fuel you can use on your vehicle is any octane that contains at max 10% ethanol.
Ethanol is an alcohol-based fuel additive made by fermenting and distilling crops that have been broken down into simple sugars.
A 10% blend of ethanol and gasoline will
not harm any engine or fuel system component. However, the ethanol has
a cleaning effect that will remove rust and other junk from the fuel
system. This necessitates frequent fuel filter changes until the fuel
system is cleaned out.
Most gas stations in our area are set like so:
87 octane (Up to 10% ethanol)
89 octane (Up to 5% ethanol)
91 octane (No ethanol)
Now we do not have 93 or 95 octane available to us here, so I am currently unsure as to what is in 95 octane fuels. In my opinion, I would use 91 octane (No ethanol) for the majority, while adding 87 or 89 octane (5-10% ethanol) ever so often to clean the lines.
I hope this helps you out,
Also if you would not mind taking a moment out of your day and rating my solution it would be greatly appreciated. Thanks in advance!