The knock I have seems spark related since it increases with engine load (going up hills, towing, running the a/c). It'd be swell if I could do the quick twist on the disty and be done with it, but of course it has none and Mr. Haynes says adjusting the timing on what I DO have isn't possible (as I'm sure most of you already know).

Anyway, just some background stuff here- Truck has 175K, I've use 87 octane since I've had it (2003) and knock seems to have increased little by little over the years. Has gotten to the point now that if I really pushed it, (up a hill in higher gear for example), I think I'd be causing some serious damage in there.

I searched previous posts and came up with ideas such as de-carboning, tightening intake manifold bolts (or replacing the gasket), and something related to egr/ vacuum leak. Before I print out the decarbon sticky & give it a whirl, I was hoping someone could expound on the other 2 suggestions or add any additional ones that could be causing all this racket?

Oh, one more thing- the CEL has been coming and going lately, and in apparent response to when knocking is at its worst (tho I may just be imagining that). Havent had a chance yet to unbend the paperclip and play samuel morse (OBDI), but I should be able to tomorrow and post what it's told me (if anything).

Thanks in advance!

 

By all means pull & post the codes, as they can offer up some good clues on where best to begin your trouble shoot.

Well depending on the trouble codes you get, the past maintenance you've done, on this vintage vehicle, vacuum line leaks belong on your suspect list & I'd probably add the PCV valve, it's hose, the EVAP system & maybe even the brake booster & it's vacuum hoses to that suspect list you've started.

Where are you on past & present due scheduled maintenance items, like air, fuel, pcv valve & spark plug replacements & were they the specified OEM, or aftermarket parts????

Does the vehicle use any oil between changes, if so how much????

 

You will need those codes to really help isolate what might be happening. I had a MAF go bad on my '94 Aerostar and it would ping going up hills. After the MAF was replaced, the knocking and pinging problem went away. So don't rule that out.

 

Thanks so much for replying, guys.

Here are the 'key on' codes I got:

335 & 522 (both repeated twice).

I then got a 1, followed by 186 & 528 (those repeated twice too).

Haynes says

335- EGR (PFE) sensor voltage out of range
522- Manual Level Position Sensor (MLP) open circuit open/ vehicle out of
gear
186- Injector pulse width higher than expected (with Baro sensor) OR
Injector pulse width higher or MAF lower than expected (without Baro
sensor)
528- Clutch pedal position (CPP) circuit failure

I did have the truck in gear when I pulled the codes, so I'm assuming that's maybe why 522 came up. I'd like to assume the injector pulse code is related to the EGR somehow, but havent had a chance to look into that further.

Since I originally posted, I noticed a crack in the air filter box and loose bolts that connect the MAF to it. Got a new one (sans the MAF) and tightened things up but I'm still having the same knock issue.

To answer some of your questions pawpaw, The truck doesnt burn much oil. At most, after 3k miles the level on the dipstick might be half what it was when changed. Plugs (cheapee Autolites) were changed last year along with the wires. Fuel filter hasnt been changed in God knows how long. Never looked at the PCV valve, evap., booster or vacuum lines. Air filter was also a year ago and it still looks clean.

Just to add some other symptoms that might be of some relevance, I find when I 1st startup the truck it runs rough for a good 20 seconds and then levels out. Engine knock isnt noticeable until it well reaches operating temps. The CEL tends to light up when I'm on the highway going up moderate to steep inclines, then disappears when I'm coasting down the other side.

 

OK, good fedback.

You may have more than one problem.

With it not pinging until warmed up, suggests a lean mixture, but that is a wild guess at this point.

With you finding a crack in the air box & the MAF sensor fastners loose, suspecting a dirty MAF sensor would be reasonable.

So maybe consider removing it & cleaning it with CRC brand MAF sensor spray cleaner, as it's formulated just for cleaning MAF sensors & is a non residual cleaner upper, that won't leave deposits that could bake on & uncalibrate the MAF sensors hot elements.

Seeing as how the EGR system isn't on line on a cold engine & the knock doesn't occur until the engine warms up & the EGR system comes on line &
with the EGR code, the EGR feedback sensor is a common problem part & belongs on your suspect list, along with the systems vacuum lines & vacuum operated diaphragms.

Cetrainly with this vintage vehicle, ALL rubber vacuum lines & fittings are suspect.

If the PCV valve hasn't been changed, do that too, because if it's sticking open, or not sealing well, it'll upset the airfuel mixture.

With the injector hgh pulse width code, If the fuel filter is clogged, it could starve the engine for flow under high demand, like hill climbing, or accelleration, enough that the system can't compensate for the reduced flow, so if you have no idea if it's ever been changed, it's time to get this puppy up to date on ALL past & present due scheduled maintenance replacement items.

These engines are kinda persnickety about the plugs they get & need double platinum ones to keep the spark gap in spec longer for our waste spark system, which works/fires the plugs twice as often as the old distributor system, so regular plugs won't last long. We also need the proper reach & heat range plug.

Certainly with this engine burning a little oil & it's age, a decarbon proceedure might be worth while.

But I'd consider a 20 oz dose of Chevrons Techron Concentrate Plus, in a full tank of Chevron, or Texaco gas, then run most of that out while doing the rpm above 3600 rpm/blow it out part of Fords decarb proceeure.

This way you won't contaminate the oil & plugs & have to change them afterward, as called for with Fords use of 3 cans of PM-3 carb cleaner in the decarb treatment proceedure.

So far this has worked well on my pushrod 4.0L, to keep my CCDI in check.

If you have over 100K miles on the O2 sensors, they belong on your suspect list too, as they may be lazy & slow to respond, so check their switching speed.

With your trouble codes & maintenance unknowns, I'd consider beginning with replacing the fuel filter & PCV valve & maybe the EGR feedback sensor & check ALL vacuum lines & fittings, clean the MAF sensor & do the Techron decarb proceeure as starters, to get a base line & see how it goes.

Edit: If you do all those things, or replace parts, or find & fix a vacuum leak, be sure to pull the battery B- cable for 20 min or so, to wipe the computers memory, so it can begin to relearn the things it needs too.

A bunch of thoughts for pondering.
Keep us posted.

 

Yup DPFE sensor & if it's OEM it may be time to think about replacing it, if it's in question.

Check out this forums "Tech Info" thread located atop the thread listing page, for DPFE sensor testing, before you replace it.

Good feedback on the recently replaced O2 sensors, so I suppose we an set them aside as suspects for now.
If you later come to suspect them, first check their switching speed, to see if any are lazy/slow to respond.

Seeing as how the vehicle is using a little oil between oci's & assuming the engine is burning the oil, rather than leaking it, don't dismiss the engine decarbon proceedure out of hand, as combustion chamber carbon deposits can cause ping too!!!!

Also if the engine is burning the oil, it probably wouldn't be a bad idea to check the EGR valve for carbon build up & clean it if called for.

While your in the Tech Info section, check out the thread about "Why Double Platinum Plugs".

 

SOrry to bug you again so soon, but would you have a part # (or numbers) for those plugs for my engine? I searched Autolites website for them....

Autolite :: Products : Double Platinum Spark Plugs

...and their search feature came up with none of those type plugs for that vehicle (or the eqivalent Ford Ranger of that year I looked up also). Kinda weird since that brand is specifically what's mentioned in the "Tech Info" section I looked at.

I just picked up some plugs from advanced auto zone (what my girlfriend calls it), but the clerk looked at me blank faced when I told him what I wanted. I picked up some Bosch Platinum Plus' while I was there, but I'm thinkin' those aren't the double type.

 

Try Motorcrafts web site online catalogue & plug in your vehicle & engines particulars & if you can't find them, at least you'd have a Ford P/N to cross reference for Autolite.

Bosch aren't thought of with favor for these engines.

 

Nevermind found it. APP765

 

Patched it! Many thanks, bearriver and pawpaw for the assistance.

If youre interested in a play by play. I replaced the fuel filter 1st (glad you mentioned that, pawpaw the old one was nearly rusted through) and then ran it, but it didnt seem to have much affect on the pinging. Then in one sitting I replaced the plugs to the double plats, cleaned the MAF with the CRC, and located a clog in that whatchamacallit line where the blowby gets reintroduced into the intake (upstream to the MAF). Took 'er out for a good hour on the freeway and barely a rattle. Feels like brand new!

 

Good feeback & to hear it's better.

After all the cleaning & maintenance, be sure to pull the B- battery cable for 20 min or so, to wipe the computers fuel trim memory, so it can begin to build new tables with the cleaned MAF sensor, new O2 sensors, ect & this may put the final polish on the job!!!!

 

One more thing that can cause pinging. If the transmission vacuum modulator diaphragm ruptures, transmission fluid gets sucked into the engine, and it will cause horrible pinging. If you find any transmission fluid inside the vacuum hose leading to the modulator, then the modulator needs to be replaced, along with all vacuum hoses.

 

You know, after I pulled the codes that time I did remove the neg. battery cable for a good hour or 2. Reconnected it, jumper wired the harness to make sure the codes were gone, but up came the same codes again. I even tried what my Haynes book suggested by pulling the jumper after I keyed on and got same thing. Did I do sumthin' wrong?

Good to know about the auto transmission cause, but I have a manual

 

If the codes came back, it means they are real codes that indicate a possible problem.

 

Yea, but I all that right in the garage. Wasnt like I drove it around.