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FLEETWOOD
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286 Posts
Will advancing the timing + 3 degrees hert the gas mileage? I'm not going to do any mods to my wifes 2.5 that will make the gas mileage go down. I will get a new muffler, and intake soon.
 

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FLEETWOOD
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286 Posts
That means the spark plugs will fire a fraction sunner?????????? If thats right, how could that help the hp????????????
 

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2,471 Posts
Ignition timing is the process whereby a voltage is delivered to a spark plug at some predetermined time (in crankshaft degrees) to ignite the fuel/air mix within a cylinder, and begin the burn.

If the mix were to be ignited when the piston reaches the top of its compression stroke (know as Top Dead Center or TDC or zero degrees), a lot of the mix would not complete its burn before the exhaust valve(s) opened to purge the engine and allow the 4-stroke process to begin all over again.

For this reason, its is much more desirable to deliver a voltage to the spark plug BEFORE the piston reaches the top of its stroke (Before Top Dead Center or BTDC or X number of degrees BTDC). This will start the burn while the piston is still compressing the mixture which also results in a multiple compression effect: (1) from mechanical compression (the piston), and (2) from the rapidly expanding and burning gases. Consequently, more of the fuel/air mix will be burned, resulting in more power, better economy, and fewer emissions.

There is a trade-off here. If the spark occurs too soon (too many degrees BTDC), pre-ignition (also called ping) will occur, and in the worse case, detonation which is an explosion instead of a controlled burn in your cylinders... VERY bad for your engine.

Most engine manufacturers call for the timing to be set between 8 and 14 degrees BTDC (obviously varies from company to company). When you advance the time further than the OEM setting, you can generally expect better performance. As long as you don't get carried away, the cost will only be the fact that you will absolutely need to always use high-octane fuel.

Hope this helps.
 

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iLoveUman
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1,116 Posts
mine was advanced another 4 degrees, i think it went from -1 to +3. I can feel something, although can't really tell if it's just the placebo to the butt dyno or not. Haven't had any pinging or other problems now for 3 months.
 

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TALL member
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11,882 Posts
even if you did get pinging...there is a knock sensor that would retard the timing if that occured so even if you didn't use high octane...the pinging would not occur. But why get the advance done if your not gonna use high octane? It wouldn't make sense so if your cheap, don't get the timing advance
 

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iLoveUman
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1,116 Posts
even if you did get pinging...there is a knock sensor that would retard the timing if that occured so even if you didn't use high octane..
i only pump 93, occassionally 94 when i can find it. I don't want the knock sensor to kick in and retard my timing cause that would just mean i wasted $40 to have it advanced in the first place.
 

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Banned
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559 Posts
Discussion Starter #14
pvick said:
Ignition timing is the process whereby a voltage is delivered to a spark plug at some predetermined time (in crankshaft degrees) to ignite the fuel/air mix within a cylinder, and begin the burn.

If the mix were to be ignited when the piston reaches the top of its compression stroke (know as Top Dead Center or TDC or zero degrees), a lot of the mix would not complete its burn before the exhaust valve(s) opened to purge the engine and allow the 4-stroke process to begin all over again.

For this reason, its is much more desirable to deliver a voltage to the spark plug BEFORE the piston reaches the top of its stroke (Before Top Dead Center or BTDC or X number of degrees BTDC). This will start the burn while the piston is still compressing the mixture which also results in a multiple compression effect: (1) from mechanical compression (the piston), and (2) from the rapidly expanding and burning gases. Consequently, more of the fuel/air mix will be burned, resulting in more power, better economy, and fewer emissions.

There is a trade-off here. If the spark occurs too soon (too many degrees BTDC), pre-ignition (also called ping) will occur, and in the worse case, detonation which is an explosion instead of a controlled burn in your cylinders... VERY bad for your engine.

Most engine manufacturers call for the timing to be set between 8 and 14 degrees BTDC (obviously varies from company to company). When you advance the time further than the OEM setting, you can generally expect better performance. As long as you don't get carried away, the cost will only be the fact that you will absolutely need to always use high-octane fuel.

Hope this helps.
Thank you!:D
 

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Registered
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2,471 Posts
To JerryJ;

I can't speak for engine management systems made today, but in my 1988 Mustang LX 302CID, it had the Ford EEC-IV ECU (speed density not mass air). Advancing the timing was accommplished just like in the pre-compute cars, by loosening the distributor yoke bold and moving the distributor cap while watching a timing light point to a scale and lines on the harmonic balancer. The effect of just going from 10 to 12 degrees was noticable. More throttle response and better overall performance.

With our Altimas, I would imagine similar results might be expected.
 

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67 Posts
Timing advance sounds like a great idea. Does anyone know of a dealer in the Long Island, New York, or New Jersy that would do it?
 
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