new 1715 question
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new 1715 question
hey everyone i just got the 1715 superchip tuner and i use 89 octane gas because i found a place that sells it the same as 87 so my question is if i am using 89 with the "87 performance" setting will this hurt anything or be bad for my truck? thanks for any help
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Joined: Mar 1998
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From: Virginia
First - to answer the actual question from "hondaman".............
Yes, you can use 89 octane on the 87 octane tune and not hurt anything. You may or may not see any extra power from doing that, it will depend on the knock sensor's calibration in your particular truck's PCM software revision (which varies widely even among identically equipped & model year F-150's). But it certainly won't hurt anything to run 89 octane on the 87 octane program, and it's not enough additional octane to cause a drop in power or fuel mileage just from the 2 additional points of octane above 87.
I do not agree that you will "make the most HP using the lowest octane that doesn't ping" on all engines - I would say that is you substituted the word "ping" with the word "detonate," then I'd agree with that, generally speaking.
We have seen in our testing that some of these trucks have enough effective compensation range in the knock sensor system's operation to be able to run 87 or 89 octane on a premium gas tune without any *audible* detonation (pinging) - most of these trucks will exhibit audible detonation if you do that, but in those that don't the motor will still immediately go down on power from the knock sensor telling the PCM detonation is present. The PCM pulls timing so quickly that you can't actually *hear* any pinging (detonation) as long as the condition is within the correctable range of the PCM & the knock sensor hardware & calibration.
How it actually works in computer controlled vehicles with an active knock sensor is, the lowest octane you can use **and not raise the knock sensor's voltage output high enough to cause the PCM to pull timing,** will generally result in the most power being made, all else being equal. No big deal, I'm just splitting hairs here in making a point not to forget about the knock sensor system's role in this................
The operative point in this regard that you guys were discussing, and I agree completely, is to not use significantly MORE octane than the engine is actually tuned for, as you generally won't get additional power gain to offset the fact that higher octane mixtures take significantly longer to ignite, and thus REQUIRE more spark advance (timing) to run correctly, to be able to burn enough of the A/F mixture to make the proper level of power & fuel mileage for that state of tune.
You can use too much octane and actually make LESS power - this is why most F-150 owners manuals tell you NOT to use premium gas, to use the 87 octane fuel it's tuned for from the factory - because not doing so can actually result in less power and mpg, and even a check engine light on the dash. This is because there wasn't enough physical time to burn enough of the higher octane A/F mixture when you use significantly more octane than the engine is actually tuned for, due to higher octane mixtures taking longer to ignite in terms of crankshaft degrees of rotation, as well as in real time. So yes, there actually IS such a thing as using too much octane, but that doesn't actually damage the engine - it just lays down & you don't make good power or get proper fuel mileage, etc.
Yes, you can use 89 octane on the 87 octane tune and not hurt anything. You may or may not see any extra power from doing that, it will depend on the knock sensor's calibration in your particular truck's PCM software revision (which varies widely even among identically equipped & model year F-150's). But it certainly won't hurt anything to run 89 octane on the 87 octane program, and it's not enough additional octane to cause a drop in power or fuel mileage just from the 2 additional points of octane above 87.
I do not agree that you will "make the most HP using the lowest octane that doesn't ping" on all engines - I would say that is you substituted the word "ping" with the word "detonate," then I'd agree with that, generally speaking.
We have seen in our testing that some of these trucks have enough effective compensation range in the knock sensor system's operation to be able to run 87 or 89 octane on a premium gas tune without any *audible* detonation (pinging) - most of these trucks will exhibit audible detonation if you do that, but in those that don't the motor will still immediately go down on power from the knock sensor telling the PCM detonation is present. The PCM pulls timing so quickly that you can't actually *hear* any pinging (detonation) as long as the condition is within the correctable range of the PCM & the knock sensor hardware & calibration.
How it actually works in computer controlled vehicles with an active knock sensor is, the lowest octane you can use **and not raise the knock sensor's voltage output high enough to cause the PCM to pull timing,** will generally result in the most power being made, all else being equal. No big deal, I'm just splitting hairs here in making a point not to forget about the knock sensor system's role in this................
The operative point in this regard that you guys were discussing, and I agree completely, is to not use significantly MORE octane than the engine is actually tuned for, as you generally won't get additional power gain to offset the fact that higher octane mixtures take significantly longer to ignite, and thus REQUIRE more spark advance (timing) to run correctly, to be able to burn enough of the A/F mixture to make the proper level of power & fuel mileage for that state of tune.
You can use too much octane and actually make LESS power - this is why most F-150 owners manuals tell you NOT to use premium gas, to use the 87 octane fuel it's tuned for from the factory - because not doing so can actually result in less power and mpg, and even a check engine light on the dash. This is because there wasn't enough physical time to burn enough of the higher octane A/F mixture when you use significantly more octane than the engine is actually tuned for, due to higher octane mixtures taking longer to ignite in terms of crankshaft degrees of rotation, as well as in real time. So yes, there actually IS such a thing as using too much octane, but that doesn't actually damage the engine - it just lays down & you don't make good power or get proper fuel mileage, etc.
