87 or 93

[scott88lss]

my book says to use 87 but i get some knocking on the highway is this a missprint in the book ?? or do i have a bad knock sensor 02 4.0 61k

[justmax]

Hello scott88lss,

Well, the 2G can use 87 octane, but it it's preferred to use 91 or higher octane gas. Why? because when you use 87, the ECU see it and take back the timing a few degrees so the engine ''runs right''. You'll loose power and MPG by using 87.

But, using 87 isn't suppose to give you knocking. Your problem is somewhere else. If your Check engine light is ON, scan it, and then we'll give you better advices. (usually, knock sensor will throw a scan code if it fails.)

If you don't have a CEL lighted up, then check plugs/plugs boots/coils.

[scott88lss]

no engine lights on !! i will try some 93 no skips or missfires any one try e3 spark plugs??

[bobsblue95]

Get the knock sensor tested. You need a scan tool that can show you KS counts, and then you hit the engine with a hammer, someplace that won't do damage obviously.

[oldwino]

Detonation can also result from too much carbon build up. You might look into doing a cleaning with a good top end cleaner or maybe Seafoam.

I run premium and top tier gas. My mileage improved when I switched to premium.

[Marc]

I have a 2001 4.0. I have always used 93.

[oneye]

I tried non-ethanol 87 just to see what would happen, have always run premium before. It might be because of the Shelby, but nothing changed other than it really woke the car up -- no documentation yet but there's been a noticeable improvement in both mileage and performance. Absolutely committed to it now, even though I have to go a half-hour through traffic and back to get it.

[human]

I hear you. When I had my '97 Cadillac Deville Concours with a 300 hp Northstar, my in-town gas mileage would go from the 16-17mpg range on non-ethanol gas to the 12-13mpg range with gasohol. Of course, that was back when you could still find unadulterated gasoline around these parts. Now, all the stations seem to have the "may contain up to 10% ethanol" stickers on them. Could be one of the reasons the '95 Aurora I have now isn't getting quite the mileage I got with my '98 when I had it.

Feb 17, 2013 6:24:45 GMT -6 oneye said:

I tried non-ethanol 87 just to see what would happen, have always run premium before. It might be because of the Shelby, but nothing changed other than it really woke the car up -- no documentation yet but there's been a noticeable improvement in both mileage and performance. Absolutely committed to it now, even though I have to go a half-hour through traffic and back to get it.

[98redaurora]

On my 1998 I always run premium, if not mid-grade. I do know previous owner usually ran 87 though. Been debating wheather or not there is a difference. I think owners manual says better economy and preformance on premium.

[fur24]

Mar 17, 2013 21:32:35 GMT -6 98redaurora said:

On my 1998 I always run premium, if not mid-grade. I do know previous owner usually ran 87 though. Been debating wheather or not there is a difference. I think owners manual says better economy and preformance on premium.

Dont do it.. lol.. idk about the fuel economy 4 sure didn't really keep track of it but performance u can definitely tell the difference.. it feels sluggish n not as quick with 87 in it.. I almost always run premium.. every once in a while a tank of midgrade

[wireless]

Premium always netted me better mileage as well so I always used it.

[Marc]

I have driven 2 2001 4.0s, my own and a demo. I knew that the demo was running on 87. It felt very down on power compared to my 2001, which I have always used 93 in, and 94 when it was available.

[sall]

Premium.

[renaldo0613]

Mar 18, 2013 9:21:47 GMT -6 sall said:

Premium.

right

[sall]

Oh yeah he has an '02 4.0L but I would still run 93 premium in it if it was me.

[98redaurora]

Mar 18, 2013 9:32:52 GMT -6 renaldo0613 said:

Mar 18, 2013 9:21:47 GMT -6 sall said:

Premium.

right

Lol......