Unusual pinging issue (2005 Ford three valve V10)

Old guy,
Yeah that's what I'm thinking. This is not a "trivial" problem and a mid-altitude new ping is not something to sneer at. Something bad is going on inside a cylinder of that engine and it won't get better. High octane fuel would be considered purely a diagnostic move. R&R spark plugs is a miserable job on this engine and I did not recommend the reading of spark plugs as a lark. I would make sure my Good Sam towing was up to date. Depends on the OP to learn the eventual fate of this issue...

I know this comparison is apple to oranges but my chev did that I took it in for service several times for the ping. they could not find out why it pinged but I got rid of it and heard they had to replace the motor at a later date.

When you fill up at a higher elevation, like in Colorado, or Utah, you imght be picking the lowest octane, and getting 85 octane, instead of 87 octane.

Running 91 octane should provide much better fuel mileage, as the engine will adjust to the slower burning fuel, and lean out the fuel mixture, as well as advance the timing to the point it might start to ping, but will give much more power out of the fuel it is consuming!

I found that I would get more than 10% better mileage on 91 octane, and right now it only costs about 5% more than the 87 octane.

Also check your fuel filter. IF you had been running low fuel pressure while climbing the hill, then it is possible when running lean, that it will ping. Running rich, it will not ping. Back in the carb days, if you had the engine set up to run lean, it was subject to running warm, and hated cheap fuel that was 87 octane, but would make great mileage and power on 89 octane fuel!

Vans used to be set up to run a little more rich, so that it would not overheat. That extra fuel would cool the pistons a bit, and the engine would run cooler.

So a hot day, low fuel pressure, it is two things that can lead to pinging. 85 octane gas that is available in the higher altitudes, that will cause it too. If you 'might' have picked up some 85 octane fuel, then I recommend topping off with 91 octane fuel right away, and then use up as much of the 'bad' low octane fuel as possible, or at least 1/2 tank, then refill with 91 octane if you will be going up more hills.

Once you are back below 2,000' elevation, you will require 87 octane again. Above 4,500' elevation, normal cars do not require 87 octane, as the compression ratio is not high enough to cause pinging on cars going in higher altitudes.

Good luck,

Fred.

What are you doing running it at full throttle up a grade in 95 F temps? Ever heard of mechanical sympathy?

Pulling plugs on this engine isn't trivial. I'd opt for the Premium and carry some octane booster. It may be that the elevation, demands on engine, and the fuel delivery controller all conspired to get some ping in the engine.

I've seen weird stuff happen like a chipped edge on a piston preignite fuel. So the answer to your problem may not arrive soon or be eaay to find. If modifying the fuel does not "cure" the pinging I sure would hesitate to take it on a long trip. Might as well hammer the fuel with Chevron Premium plus add Techron. Sometimes a chipped center electrode insulator of a spark plug will cause pinging. In any event yank the plugs and read the clues on the center insulator. Be especially on the lookout for a mottled or speckled insulator.

dump a bottle of Lucas in

Use a higher octane fuel if you are not at the highest now.

Is the engine running hotter than normal?

Maybe the knock sensor has failed, read up on that subject. I have never tested or replaced that item.

Maybe you just got a load of lousy fuel. Run it low and try a tank of premium from someone like Chevron.