My Father in law's 99 Ranger V-6 Spark Plugs keep fowling about once every six months.

Any ideas as to what could be causing this would be much appreciated?

Thank you,

Dave

 

Give us some more information. What brand of plug does he use? Are they of the correct heat range? One possibility is that they are not hot enough to burn off deposits. Does the engine burn any oil? What type of driving does he do? Is it mostly slow driving around town? Does he do any hiway driving at legal speed limits?

 

Yup as michigan66 said, we need more info to make a better guess.

Which engine does he have, how many miles on it & what kind of plug flouling is he having, oil, carbon, coolant????

What brand & octane fuel is he running.

What brand plugs, wires & air filter????
EDIT: What weight oil is he using????

 

Possible flakey mass air flow meter/sensor?

 

Sorry that it has taken so long to get back with you. I was following up on this for my father in law and then I got stuck doing a great deal of travelling for my job.

In any case, here are the details of what has transpired with this thing since he bought it.

The Ranger is a 4.0 L V-6 built on 03/99.

As I understand it, similar to my 99 F-150 he has had several occasions where the Ranger started to run rough, and threw an error message of fouled plug #..... When the plugs are changed, error clears and everything runs fine. This happened every five to six months with different plugs and then this last time it was the same plug that fouled twice in a row and changing the plug doesnt fix it.

The truck starts fine but barely runs. You step on the gas and get to 35 to 40 MPH and it coughs so hard that you cannot drive it.

He took it back to the mechanic who had been resolving the issue before by changing the plugs defined in the error code, however, this time they told him that they changed the plug, but it did not resolve the issue and the code was clear, no more codes came up, but the truck still runs the same (badly).

With more details hopefully one of you has a better idea as to what might be happening here?

Thank you in advance for any suggestions/resolutions.

Dave

PS I am thinking possibly the coil pack? It appears that this V-6 has one coil pack that all of the plug wires plug in to? What are the chances of that and what should this one cost him to replace?

The truck now has 115,600 miles on it.

 

One more thing that I had neglected to mention. Father in law is in California and the truck likely has California Emissions on them (But maybe they all do now?). Thanks....

 

Has your father-in-law considered going to a different mechanic. The problem is more than just a change of spark plug. Has the mechanic considered anything else? Are you using Motorcraft plugs? Rangers seem partial to them. Other brands seem to cause problems. Are any other trouble codes displayed? What brand of fuel is used? Have any of the other suggestions been checked out? The mechanic seems to only be addressing the obvious problem but is not digging deeper to identify and correct the root problem.

Keep us posted on the progress.

 

OK so it's a 99 4.0L with 115K on it & the Tech has replaced the plugs a number of times & cleared the misfire codes & it'll run ok for a while, then the rough running returns in about 5-6 months with cyl misfire codes again.

It's running poorly again & the same cyl has fouled it's plug twice & replacing that plug doesn't clear the problem & it's running poorly at 35-40 mph & coughing & chugging so bad that it not driveable.

He may have more than one problem & I agree his Tech isn't looking deep enough to find the root cause problem.

So list ALL of the trouble code Numbers he's had.

With 115K miles on it, a number of scheduled maintenance items are due, so where is he on ALL past & present due scheduled maintenance items???

Good answers to All of the guys previously asked questions would likely help narrow down the guess list.

Right now it would be helpful to have a really good "plug read", to know what kind of plug fouling he's had & especially on the cyl that's now fouled it's plug twice.
Again, how are the plugs fouled, carbon, oil, ash, cooalnt, ect????

All kinds of possibilities abound, so we need more detail to offer up a better guess.

He could have a mechanical problem(sticking rings, bad valve stem seals, leaking fuel injectors, ect), electrical (bad plugs, bad wires, acting out colpack as you've proposed), wrong part, (wrong spark plugs or wires, wrong oil weight, wrong PCV valve), Bad worn out dirty parts (Lazy O2 sensors, dirty MAF sensor, clogged up PCV valve, dirty or worn out fuel injectors, bad pug wires, bad TPS sensor, clogged up air or fuel filter), or some combination thereof.
So all kinds of possibilities abound, at this point, you really need more detail & imo it seems to me a good "plug read" sure would help narrow down the possibilities at this point.

Most autoparts stores can bench check the coil pack at no charge.

A bunch more thoughts for pondering.

 

Great thoughts gentlemen. One detail that I had mentioned before is that this last round the truck is running bad with no codes coming from computer. This unlike the previous times when the truck threw the code that the plugs were bad, this time after changing the plugs, the truck ran bad, the code went away and didnt come back.

The mechanic didnt tell him how the plugs were fouled, just that this was common in the ranger.

I agree that more needs to be researched, I just hoped that someone may have had this same experience and know the most likely part to start with in this case.

Thanks to all!

Dave

 

Well with it acting out again, but with no codes this time, it could be number of things, maybe bad plug wires, coilpack, or fuel injectors.

This Ranger has a "waste spark" ignition system & as such, there are only 3 coils in the coil pack, to fire all 6 plugs.
So the plugs are paired such that one plug is fired on it's compression stroke, while it's companion is fired on it's exhaust stroke (waste spark).

So if we knew which plugs were fouling out, it might offer up a clue to your suspicions about the coil pack, especially if the acting out plugs were paired at the coil pack.

It's Not normal for the Ranger to have fouled plugs!!!!

If the plugs are carbon fouled, suspect a fuel trim problem. Maybe a clogged air filter, or a fuel pressure problem, or fuel injector problem.

Fuel fouled, suspect excessive fuel pressure, maf sensor, TPS sensor, O2 sensors, dirty or leaking fuel injectors.

Oil fouled, suspect sticking, worn, broken rings, worn valve guides, leaking valve stem seals, plugged PCV valve, wrong viscosity oil.

So maybe have him call his Tech & ask him for a "plug read"

 

Thank you. Much appreciate the information.

It seems at this point he may need to start with the least expensive part replacement and work forward. Being that when the plugs were fouled, he was not told how they were fouled.

HOw much should the replacement of that Coil pack be? It appears to be only four bolts and a connector. Is that correct? Looks pretty simple, and from my look I believe that he can handle that.

Thanks,

Dave

 

IMO Don't start throwing parts at this problem, as it could part him to death & not yield the results you want.

Even if you wanted to begin throwing parts at it, you still don't have enough info to know where to begin, to maybe get lucky.

You really need to know what kind of plug fouling he's been having, to maybe guess which system has a problem & whats going on. So have him call the Tech, or look on his repair sheet for what was found, or what trouble codes were listed.

Or maybe consider taking it to a Ford Dealer that has a good reputation, to get a proper trouble shoot & diagnosis, as it could be less costly in the long run.

All that said, if your still gonna throw parts at it anyway, maybe consider beginning by bringing the vehicle up to date on all past & present due scheduled maintenance item replacements, like air & fuel filters, pcv valve, plug wires & maybe the specified plugs, if the replacements aren't such & O2 sensors, as all of these are normally replaced around 100K miles.

As it was never mentioned that the plug wires were replaced when the plugs were & we still don't know what kind of plugs are being used, maybe begin with those items.

Because this waste spark ignition system works our plugs & wires TWICE as hard (remember they are fired on the compression & exhaust stroke) & it gives a reverse polarity spark on one bank of cylinders, we need double platinum replacement spark plugs of the proper heat range, to control gap erosion & a danged good set of plug wires to stand up to the extra work load.
So Morotcraft, or Autolite plugs & wires are recommended, as autolite makes Motorcraft plugs, not sure who makes Motorcraft plug wires though.
I use all Motorcraft as they are of very good quality & designed for the engine & work load.

The coil pack isn't gonna be cheap, so if your of mind to just replace it, at least have it bench checked first. Most autoparts stores can do this & at no charge & yes it's easy to pull as you've described.

SO, at this point, with the mileage on the vehicle & not knowing it's service history, if your gonna begin throwing parts at the problem without a proper troubleshoot & diagnosis, I'd start by bringing the vehicle up to date on ALL scheduled maintenance items listed above & probably install a set of new Motorcraft plug wires & Motorcraft double platinum plugs, if the replacements aren't double platinum plugs & new O2 sensors .

Make sure he's using the specified viscosity & service grade oil & filter.

Have him run most of the current tank of gas out, then add a 20oz bottle of Techron Concentrate Plus at the pump & then fill up with Chevron, Texaco, or CalTex gas.
As these fuels already have Techron in them, this will raise the treat rate 10x above the pump gas level & can tidy up the fuel system, fuel injectors, intake valves & combustion chamber in one tank.
Have him run most of that treated tank out with some spirited driving sessions & see how it goes.

A whole bunch of thoughts for consideration, let us know how it goes.

 

The next time you pull a fouled plug or pull the plug on that cylinder, examine it with a good magnifying glass or eye loupe. Look for small water droplets. Some of these engines get small cracks in the heads.

 

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Hi the first thing I would check is if there is fuel in the vacuum lines to the fuel pressure regulator. If there is fuel in the vacuum lines replace the regulator an fuel fouling should go away run much better and improve fuel economy good luck. This will also cause right or left bank of engine not to work. It can drive you crazy if you don’t know what to look for

 

hello, if problem persists, do a leak down test. It won’t cost you any money if you can perform yourself, my 4.0 v6 had same problem as you, turns out my exhaust valve on cyl 5 chipped a piece off and lost all compression there, just an idea