I'll fill my Ranger (2000 3.0 flex fuel automatic) with 93 octane whenever I'm pulling my camper. When I'm not pulling or hauling cargo, I'll use 87 octane.

I notice that when I fill up with the 87, the engine will ping/knock a bit under medium to hard excelleration.

Is this due to the PCM still mapping with the 93? Does it take a few miles for the PCM to re-learn with the lower octane fuel?

 

Octane numbers are a heat rating not power rating so there is no change needed in PCM from one octane to the next.
PCM does change length of time injectors are open as methanol % goes up because methanol has less power per gallon than gasoline, a fuel sensor was used in early Flex Fuels vehicles, but it was dropped as newer computer software allowed longer open times without sensor confirmation.

Pinging is when the air/fuel mix self ignites from heat in the cylinder, the noise is caused from at least 2 separate "explosions" in one cylinder, when the wavefronts meet it makes the pinging noise.
87 octane will self ignite at a lower temperature than 93, or 89, this is why running a higher octane number can reduce pinging.
Pinging is nothing to sneeze at, if it continues long enough pistons and valves will melt.
Pinging creates more heat, so is self sustaining, i.e. one ping creates more pings, so once a cylinder starts to ping it will continue to ping until cause that started it is removed, which could be cooling down to "normal" heat levels.

Compression is heat, so the higher the compression ratio the hotter the air/fuel will get on the compression stroke, 9.4:1 is about the limit to run 87 octane fuel, and everything needs to be working perfectly or you will get pinging.
High compression engines have to run higher octane fuel, not for more power but because of pinging, self ignition with lower octane.


When you accelerate, go uphill or pull a trailer the load on the engine increases, this causes cylinders to heat up, that is normal, and if everything is working as it should there should be no pinging.

The 3.0l can run on 87 octane without pinging, compression ratio is 9.3:1, it is designed that way, but it is close to the limit for 87 octane, so any other systems running out of parameters can cause pinging to occur with 87 octane.

A lean air/fuel mix is more prone to self igniting, small vacuum leak can cause this.

Carbon build up in a cylinder retains heat and can get "hot spots" that can ignite air/fuel before spark plug does, carbon build up comes from running rich for a long time.

The EGR system is there to lower NOx emissions, it does that by lowering cylinder temperatures when engine under load, so EGR system also helps prevent pinging.
If EGR valve/tube is partially clogged you may not be getting enough exhaust gases into the intake.

Some engines used a Knock(ping) sensor, this retarded the spark timing when pinging was detected, so spark plug ignites the air/fuel before it can self ignite, this reduces power but is better than pinging.

If your spark is advancing too much then pinging will occur.

Also make sure you are running the correct spark plugs, the correct heat range specifically, wrong range can retain too much heat and spark plug tip can ignite air/fuel early.

 

I hope I described this correctly...it's like a rattle, resembling some nuts and bolts being shook in a can. If I let off the gas, it stops of course, and if I lightly accelerate, it's not as bad, or goes away.

On some of the newer cars from Ford I've owned, I knew they had the ability to adjust the timing based on octane used; my Mustang will run better (more power felt) when I use 93 octane, verses the 87 it states it can use. I figured most PCM's could adjust the timing based on a knock sensor, which in theory, would knock with lower octane verses higher octane used.

I'll check the plug types to see if they are correct, and remove/inspect the EGR.

 

Yes, that sounds like pre-detonation/pinging/knocking

Yes, your Mustang must have a knock sensor if you felt more power running higher octane.
Knock sensors detect the start of pinging/knocking before you hear it, so you wouldn't know spark timing was retarded using 87 octane, and when using higher octane the spark can be kept more advanced, so more power.

Your Ranger doesn't have a knock sensor.
The Ranger 4.0l SOHC engines do, and need it, they are way passed border line running 87 octane with 9.7:1 compression ratio

 

So in my case, I should not be hearing this running 87 octane? The truck idles perfect, so I never suspected a faulty EGR or its controller, or a vacuum leak in one of its hoses. For kicks and giggles, I can remove the vacuum port from the EGR once warmed to see if it stumbles, stalls, or drops idle for testing its operation.

But because I seem to have spare time on the weekends now (cooler weather does not require me to mow the grass as often), I can remove and clean the EGR, and inspect the tube from the EGR to exhaust manifold at the same time.

 

No, not normal, but many engines are prone to pinging, 2.3l Limas are examples of that.
And any engine can start pinging because of a change in its system.

There is an underlying cause for it, no major company designs an engine that would ping when new, assuming "regular gas" is specified.

It is kinda like the head lights dimming at idle being "normal", it isn't, lol, no car maker would spec an alternator that couldn't power the whole system at idle RPMs.
It's a sign that an alternator field has failed or you have added an extra non-factory power draw.

Pinging is the same thing, not "normal", could even be your local 87 octane is actually 85 octane, making customers buy 89 or 91 octane.
Like serving salty "free" snacks at Bars, to sell more drinks

 

I'm using Shell gas, so hopefully this station is not doing any sort of switcheroo on me. I've always had good results with Shell and Mobile, so I stick with them. They supply the Techron additive to all grades, and I've yet to ever have a dirty or failed injector.

In reading up on all the components of the EGR system on the 3.0, I see these components that make up the EGR system:

1) EGR Valve
2) EGR tube
3) EGR Valve Control Solenoid
4) DPFE (Differential Pressure Feed Back sensor)

From many of these articles and posts, they suggest starting with the DPFE if you have issues with the EGR. I have no codes, only the rattling noise associated with engine ping. Since the EGR is used to help cool cylinder temps, and assist preventing ping, I'm concerned with it's operation.

Other items that show up for pinging are a TSP that Ford issued (00-7-3) that mentions a coil pack issue and a PCM reflash performed if a customer complains of pinging. It states that if your coil pack part number range is 7001 to 9213, it should be replaced with F5S2-12029-A (FOMOCO; not sure if an aftermarket coil pack would also be updated). Other posts have stated owners who have had this TSB done, and pinging still happened on grades or hard excell, so they simply stepped up to a higher octane, and pinging was eliminated. My 3.0 is a 9 to 1 compression ratio, so 87 should be fine. But it pings with 87. I may try some seafoam in the tank to see if maybe some carbon buildup on the pistins is adding to the pre-ignition problem, as I have not owned this truck since new, and it's more than likely that cheaper gas (with no additives) have been used, and some carbon buildup has occured on the pistons.

I also had my cam sensor and housing replaced about 3 months ago, so timing should not be an issue. The truck runs great; my only concern is the pinging on medium to hard excelleration.

 

Ford DPFE sensors last about 60k-70k miles, non-Ford replacements seem to last longer.
The DPFE hoses are important since this is a pressure difference sensor and the hoses are hooked to very hot exhaust manifold parts, so can dry out and crack, which would lead to incorrect pressure differences.

Ford had a TSB covering '98-'00 3.0l engines and pinging
Google: TSB 00-24-08

They blame a coil issue, and then a PCM swap if that doesn't fix it.
But if you read further, #9, there is a setting in the PCM a Ford dealer can reset

 

Does a dealer charge to perform a TSB service? As I understand it, it's sort of a "silent" recall; only those who complain of a symptom get the TSB fix. Obviously, my truck is way beyond the mileage and year for warranty work. However, if this pinging was a fault of Ford's faulty coil pack, or a PCM flash/reset, why would a person have to pay for that?

I'll replace a coil pack; that's easy. But I have no way to do anything about the PCM, unless I stumble across one at a junkyard that had this modification. However, that's a crapshoot, inless Ford or the dealer put some sort of label on the PCM after it was changed, how would I know I have one with this change?

I think I can go to a dealer and have them check my VIN to see if it had any TSB corrections made. Lets assume mine did not have this TSB done (and it pings, so I doubt it unless I have another issue). Do I have to pay for the TSB to be performed now?

 

A TSB is not a recall, if a problem requiring a TSB is wide spread enough Ford may send out a Notification Letter, but it still falls to the owner to take action, or to notice a problem and bring vehicle to dealership for service.

If you were the original owner and were taking vehicle to dealer for regular service they might do a TSB repair free or at least cheaper if it was out of warranty.

But at 14 years old I doubt they would cover it.

Problem is the Dealer has to eat the cost of parts on out of warranty repairs, Ford probably wouldn't pay replacement cost, if for sure won't pay for any labor.

 

That's what I figured. Cheaper for me to perform some of the repairs, although if the ping still persists after a check/repair of the EGR system, the ignition system, and any potential carbon build up on the pistons, then the PCM could be a target (as per the TSB change).

I'd just step up to some higher octane and call it a day.

 

Issue resolved. While I dislike tossing many parts at a symptom to fix it, I did purchase a new coil pack (part number recommendation from the TSP), a set of new plug wires, and a set of Motorcraft spark plugs. I also purchased and installed a new DPFE and new vacuum lines for it.

HUGE difference in how it runs! While the engine ran good before, it's much better now. The pinging is gone.

Since I had no idea or record of any previous service to this engine, I decided to give it a complete ignition overhaul of sorts. The original coil pack had a low production number, and as per the TSP, this could lead to the pinging issue.

I also wanted to remove the plugs to get an idea on how the cylinders looked; all 6 plugs were very clean, but I was concerned on the plugs used. The ones I removed were Motorcraft, and had two tapered blades. These plugs appeared to be way too clean, and the surface was more on the whitish side, making me think the engine was burning a lean. So as per the Ford factory repair manual, I installed AGSF22P (AGSF22PPM replaces these) for my flexfuel 3.0 (year 2000 only), I installed them, along with a new set of plug wires, and the Motorcraft coil pack. I set the plug gap to .045.

Wow, what a difference. No pinging at all. It's my understanding from research that these "22's"are colder plugs, which Ford stated should be used.

I also discovered that the passenger side rear plug (closest to the firewall) had some oil on it's outside surface and around the hole, telling me that the valve cover gasket is leaking, so this weekend will have me changing that out.

 

Good work

Reads like a well spent weekend, and good info on the results.

Yes, colder plugs retain less heat so are a few degrees cooler under normal operation than next warmer plug, and that few degrees can be the difference in pre-ignition or no pre-ignition with regular gas.
I think most spark plug makers use lower numbers for hot and higher numbers for cold.
So a "22" would be cooler than a "20"

Coil could be delaying spark(milliseconds matter), giving pre-ignition a chance to start or using too hot of a spark causing cooler plug to run hotter, a few degrees matter.