4.0l engine ping

[outlawii]

hello all, new here, and need some help. had an '04 with 4.0 and 5 spd manual. no problems. just bought a 2005 with same engine but auto o/d. getting quite a bit of eng ping. have ran two cans of chevron techron thru, along with upgrade to premium ( top tier) gas. still pings. gets 17 mpg on hwy runs strong- but hate the ping. any suggestions more than welcome, thanks larry

 

[SenorNoob]

Howdy and welcome to TRS.

Just one question: Are you sure it's detonation and not something else like an exhaust leak?

 

[outlawii]

I am sure it is ping- has all new exhaust, also had a master certified mechanic ride with me- he sez ping, and told me to try the chevron. next step $150 injector clean or what? anyone else experience this?

 

[RonD]

Check the gap on a couple of spark plugs, also their tip condition.

Should be 0.054"
If larger, spark can be delayed(advanced), and you may want to change them to 0.049" so they spark sooner(retard spark)

2001-2005 4.0l SOHC uses SP498 (Platinum) (old part number is AGSF34FP) or SP412 (Nickel)

Pinging is, of course, the fuel/air mixture self-igniting just prior to the spark plug firing, the noise is the result of the two separate "explosion" wave fronts meeting in the cylinder.
Pinging causes extra heat in the cylinder(and can cause piston damage), so once a cylinder starts to ping it can be self sustaining because of the extra heat.
Self-ignition is all about heat, it can be actual hot spots in the cylinder, or from compression heat.
Octane is a heat rating, higher octane has a higher self-ignition temp, that's why pinging will often go away with higher octane gas.
4.0l has a 9.0:1 compression ratio, so can run 87 octane fuel without pre-ignition.
When you get up to 9.4:1 is when 87 octane can get pingy

If engine doesn't ping at all when engine is cold, then I would suspect some carbon build up in the cylinders creating higher compression and hot spots.

Engine makers run fuel/air mixture right at the edge of the "perfect" mixture, but slightly rich, this is to get the best MPG without melting the pistons, the "prefect" mix will melt pistons in a minute or two, lol.

This is why slight out of parameter conditions can result in pinging.
A lean mix has two things against it, it cools the cylinder less and is easier to self-ignite from hot spots.

If possible I would look at the real time OBD II data, the fuel trim data, to see if it is looking too lean.

Small air leak in PCV hose(common on Rangers) or power brake hose can lean out fuel air too much, I would expect Computer to fix that or turn on CEL but...........??
With engine warmed up and idling, unplug the IAC valve, idle should drop down to 500rpm or engine may stall, either is fine, if idle doesn't drop then you have an air leak.

The EGR system, if so equipped, is there to reduce NOx emissions, it does this by cooling the cylinders when they are under load and heating up.
As odd as it may sound the hot exhaust being mixed with the fuel/air and burned in a cylinder actually cools the cylinder more than running just the fuel/air mix.
If EGR valve or pipe starts getting carbon build up inside then exhaust gas flow is reduced, so cylinders heat up a little more than they should.

 

[outlawii]

ron, can't thank you enough! I really appreciate the knowledge and your passing it on! I am printing this to take to my mechanic this Tuesday, I will let ya know how I come out. again, thanks, regards, larry

 

[outlawii]

well so far have new plugs and plug wires, had fuel injectors cleaned by mechanic, have BG44 in fuel tank, new maf sensor. still getting some pinging, tho not as bad. runs like a race car!. what now? new coil pack? new egr valve? could I be hearing lifters needing adjustment? any help greatly appreciated

 

[RonD]

When do you get the pinging?
Under load like when going up a hill.

The 4.0l SOHC doesn't have lifters so any top end noise is probably the injectors, Ford injectors "tick" pretty loud.
Use a hose as a stethoscope and listen to an injector.

 

[gw33gp]

If larger, spark can be delayed(advanced), and you may want to change them to 0.049" so they spark sooner(retard spark)

The EGR system, if so equipped, is there to reduce NOx emissions, it does this by cooling the cylinders when they are under load and heating up.
As odd as it may sound the hot exhaust being mixed with the fuel/air and burned in a cylinder actually cools the cylinder more than running just the fuel/air mix.

Are you sure you got the larger gap, delayed spark (advanced) and spark sooner (retard spark) thing correct? Usually a delayed spark would be retarded and a sooner spark would be advanced.

Introducing the exhaust gasses into the cylinder to cool it is not as odd as it may seem. It is a way of diluting the air/fuel mixture without adding oxygen that would cause a lean condition. It may be hot but it does not contribute to the combustion process, so, it does not add heat. The introduced exhaust gas is not as hot as the combustion of the new air fuel mixture because it has had time to cool a little while being recycled.

 

[outlawii]

spark plugs are correct, egr system checked, pinging is most definitely worse under load, while accelerating. cruising with cruise set at 70 mph it is pretty quiet. will try your hose idea. thanks much, will let ya know.

 

[RonD]

Yes, if the spark is advanced to far(delayed), you want to retard the spark so spark plug fires before pinging can start, that is what "knock detectors" did, retarded the spark timing.

Pinging under load is the most common because that's when cylinders normally heat up and pre-ignition starts.
I think it would be worth while to have a look in the EGR valve and pipe.
Also check the vacuum hoses on the EGR modulator(it opens the EGR valve)
And the hoses on the DPFE sensor, these two hoses connect to the exhaust, one close to the EGR valve and one farther away, the DPFE sensor uses the pressure differences between these two hoses to tell how far the EGR valve is open.
The hose and the exhaust ports they connect to need to be open, build up of carbon can cause EGR valve not to be opened enough

 

[outlawii]

well, I was told to try a oil additive. changed oil, put in Castrol gtx high mileage synthetic blend and 15 oz of rislone additive and the noise is now history. also was told an old mechanic trick is to add I quart of tranny fluid with each oil change, it will cleanse the engine and lubricate seals etc. if the former owner of my truck didn't change oil regularly then that is where the noise was coming from. carbon build up.

 

[outlawii]

I was told by a different mechanic to try an oil additive- put in Castrol gtx hi mileage oil and 1 can of rislone oil treatment. noise all but gone. believe I need a good internal engine clean. may try adding I quart of tranny fluid to next oil change, I am told that is old mechanic trick to slowly, safely clean an engine, getting rid of sludge and carbon, which can cause rattle or ping.

 

[RonD]

Well the "carbon build up" that causes pinging would be in the cylinder chambers and tops of pistons, so oil additives wouldn't help with that.
Carbon build up can come from constant over rich fuel mix(how is your MPG?) and/or oil leaking past rings or down intake valve guides with cracked seals, oil additives can slow this leaking down, but never seen it reverse the build up.
There are basically two ways to clean out this cylinder carbon.
1. remove the heads and clean them and the tops of the pistons.

2. a little riskier, use a fluid like Seafoam, and with engine warm and idling pour some into the intake, via vacuum hose, just a little, repeat a few times.
If you put in too much a cylinder can HydroLock from the fluid and engine will suddenly stop and a rod will bend or piston will break.
It is safe if done right, but the "screw up potential" has an expensive downside.

And with #2 that carbon will go out the exhaust valves and into the Cats and muffler, so ........might be good idea have those disconnected while doing this.

Lifter noise can be quieted with oil additives or a higher "weight" oil.
If you pull off a valve cover you can usually see if sludge is present in the top end, if so then bottom end will also have it.
Yes, adding AFT just before an oil change will help clean out oil passages and some sludge.

 

[gw33gp]

There is a mechanism in which oil additives can reduce pinging. Oil in the combustion chamber reduces the octane of the fuel. Additives that reduce the amount of oil in the combustion chamber by any means will have the affect of raising the octane. This could be by freeing up rings that were gummed up and allowing oil to pass or helping them to seal better. Higher octane means more resistance to pinging.

I know synthetic oil is recommended when going for emissions testing. It tends to lower the hydrocarbons in the exhaust. I don't know if that is related to pinging but could be a contributor.