Pinging on Highway
 

My stock 2006 F350 was pinging like crazy on the highway yesterday at 80 MPH. I was running 2800 RPM. I have a manifold leak, but don't think this is it. I'm sure this thing has got a ton of deferred maintenance, but don't even know where to start. It's a manual transmission with 170k miles on it, chassis cab. I've got a 500 mile return trip home friday, would like to fix it here if it's simple. No CEL.

It also seems a little low on power, but maybe that's not really it. I just thought a 3v engine would be a little more responsive. I'm running 87 octane.

I’m sorry no one has responded to you. That’s abnormal on FTE.

Sounds to to me like catalytic converters. Seems like every ford I’ve owned has them go bad around 200,000 miles.
2000 Contour,
2003 E250,
2007 E350,
2010 Escape (only has 140,000)

And now that I think of it; maybe the extra back pressure from the cats is causing the manifold gaskets to fail.

Does yours sputter and struggle at medium-high throttle input?
And/or medium-high rpm?
also I’ve read about using a laser thermometer to check the temperature of the inlet and outlet of each cat to judge if it’s plugged up. Spend an hour on YouTube researching this method though. I don’t know what temp spread is acceptable.

if so- I bet you have at least one bad catalytic converter.

Im50Fast is dead on. I have been going nuts with this issue with my 2004 E450 SuperDuty 6.8L. Turns out the Catalytic Converter was clogged. 78k miles on it. Just had it changed and the pinging is completely gone and the power is SUPER! Do not have the dealer change it though...lol. Dealer price on the converter is over $2,000.00. Got it changed with labor in a shop in Mesa Arizona for $600.00. Could not be happier.

A vacuum guage can tell you if your exhaust is plugged up.

https://www.ericthecarguy.com/faq/so...t-restrictions

Turns out the problem virtually went away with 91 octane gas. I’d like to not keep putting this in there but that makes the converter seem unlikely. Any other ideas?

Now I’m worried my gas mileage is going to suck because I’m actually using the throttle

Should not ping on 87 octane.
Something is not right.
Could be running lean
Check O2 sensors

No cel. I know they could still be bad, Are those something I can check myself?

you could try the suggestions in posts 2,3, and 4 above.

If it were a plugged catalytic converter why would it go away with higher octane fuel? The fact that the fuel made a difference made me think that it Has to be something in the engine management system. Oxygen sensor makes a lot of sense. I know that with the scan tool there are ways to test them but I wasn’t sure if there was a way to do it otherwise. It may not matter because I called the part store and sounds like they’re only $25 apiece. With 200,000 miles on them I will probably just replace them anyway.

1st why do you think a manifold leak is not the cause?

2nd do the deferred maintenance

3rd I suggest making sure injectors are all in good condition, one or 2 that are not spraying or partially working will cause lean condition in those cylinders. This in turn will make other cylinders too rich, because O2 sensors will try to compensate.

pinging and the manifold leak are different noises. Pinging is more irregular and happens at load, the manifold leak is constant. It needs fixed, will probably go to the mechanic next week. I’m not doing the manifold.

no cel currently but I had a persistent misfire when cold this winter. That sounds a lot like what you talk about with the missing. It’s beginning to sound more and more like I’m going to have to just take it to the mechanic and let him diagnose it with the scan tool. I was hoping to save some money if it was something simple by doing it myself before taking it to him.

Ok, let's look at the exhaust manifold leaking.

It may not be the the "sound" you are hearing, but may cause pinging.

As exhaust excapes the manifold via leaks the O2 sensors, that are down stream from the leaks, are not sensing the correct air fuel ratio.

Maybe the O2 sensors are making the motor or a bank run lean because they are sensing the wrong reading due to exhaust manifold leaks.

Hmm....hadn’t considered that. It’s getting the new manifold next week. Guess I’ll wait till then to see if it still does it.

I disagree completely.

Exhaust manifold leaks won’t cause your engine to run bad, nor cause steady highway pinging. And it doesn’t cause wrong o2 readings.
People always says that, but think about it like if your exhaust manifolds and exhaust pipes were flowing water instead of hot exhaust: ok great some water leaks at the mating surface of the head and manifold. But the manifold is still full. It’s not magically sucking outside atmosphere into the stream; because the exhaust system has pressure, not vacuum. A pressurized leak is just a leak. The exhaust system is still full of exhaust, even though it’s leaking some.

Ive read your posts repeatedly and it still seems like catalytic converter(s).
Could be bad spark plugs or bad fuel or anything else basic. But steady spark knock at highway speeds is almost certainly caused by excessive exhaust back pressure IF coupled with low power.

Which leads to my questions above, that you didn’t answer:
Does your engine sputter and struggle at medium-high throttle input while driving? And/or medium-high rpm?

Two separate questions there, read and reread- don’t just answer quickly.