What recommened grade of gas to fill up your expedition?

FordGirl1983 · Dec 28, 2014

When accelerating on the road, the noise get a bit louder. Oh I don't think it was a "pinging" noise, it's more like a bubbling, flapping noise. I try my best to describe the noise better lol.

98EXPnSRQ · Dec 29, 2014

I had a slight ping when accelerating on 87 octane. It went away when I changed the spark plugs.

FordGirl1983 · Dec 29, 2014

A little update this morning on my commute, I filled it with mid grade and the rattling sound went away. I assumed that sound is from "bad gas". That's all I know so far.

98EXPnSRQ · Dec 29, 2014

Yep, bad gas will do it too. Switch gas stations.

FordGirl1983 · Dec 29, 2014

Yes sure did switched gas stations.

montecarlo31 · Dec 29, 2014

What are you seeing for timing advance and what are you seeing for retard? If it's going away with a 2 point increase sounds like timing or a plug issue. I'd test coils and replace plugs / wires. While you are in there might as well do air and fuel filters to knock out the big stuff.

toms89 · Dec 29, 2014

I fill up with the highest octane possible but mine is running boost.

The higher the octane the more aggressive I can get with the tune.

tojohnso · Dec 29, 2014

in my '99 the only issue I had was when I put in 93 thinking I would get better mileage on the highway. If the engine isn't tuned for it, bad idea. I normally filled with 87/89 whichever was available and cheaper. I do the same now with my '11.

hammerg26 · Dec 30, 2014

stamp11127 said:
Unless you have a 5.4 DOHC your engine is designed for 87 octane. If it is pinging on that octane you have a problem that is causing pre - ignition.

What octane is the 99 5.4 designed for?

thewishkah · Dec 31, 2014

I used to use 87 now I mostly use 89, with 87 the truck felt sluggish and would rough idle once in a while. Even after replacing the air filter, gas filter, spark plugs, pcv valve and cleaning the egr ports that were mostly clogged. All of those things didn't help my gas mileage at all. Never had a CEL but I think my coil packs are next on the list. I decided to try 89 after gas prices started to fall and it runs better, and has more pep when on the pedal.

What recommened grade of gas to fill up your expedition?

FordGirl1983

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