pinging 2002 with 140k

[mrscullini]

i've got an '02 4wd with the 4.0l sohc. it's got 140k on the clock.

i've got a ping under load, even light loads. when it happens the engine speed is about 2500 rpm, if i down shift and bump the speed to 3k, the ping is still there. as soon as i get on a flat surface the ping disappears.

don't laugh, i last replaced the plugs at 100k, could this be the problem? could it be a knock sensor? i recently did a seafoam treatment, very little smoke during the treatment but could this have fouled my plugs?

i will replace the plugs in the next couple of days. in the meantime i will try some mid-grade fuel to mitigate the situation.

any thoughts, insight?

 

[Big Jim M]

As you prolly know, pinging is caused by too much timing...or too lean fuel mixture...or too much compression.. Or even a combination of these. I'm thinking whatever it was that you ran thru there didn't all get out! And you have a residue on the tops of the pistons causing too much compression.
If higher test makes the ping go away run it a while and maybe it will clean itself up.
Of course there are other senders and parts that could have went away also.
Big JIm

 

[Donnie strickland]

Also a dirty MAF sensor can cause this. My truck had the same problem. Do a search for "MAF sensor clean".

Also, read the article in the Tech Library:

http://www.therangerstation.com/tech_library/CleanMAF.html

 

[mrscullini]

thanks for the reply big jim. you are right, i do understand the basic of combustion. if i understand correctly, timing is controlled electronically and there are no manual adjustments. with this, i figured the knock sensor would retard the timing to mitigate the pinging.

would a bad knock sensor throw a code? the cel is not illuminated. tomorrow morning i will try an italian tune up and see if that blows out anything.

 

[mrscullini]

Also a dirty MAF sensor can cause this. My truck had the same problem. Do a search for "MAF sensor clean".

Also, read the article in the Tech Library:

http://www.therangerstation.com/tech_library/CleanMAF.html

i cleaned the maf sensor not just a couple of weeks ago. but who knows, i will give it a try again.

 

[mrscullini]

follow up info

so, i cleaned the maf sensor no luck, the ping remains.

the ping seems to only happen during my afternoon commute, not morning commute. so i thought maybe cylinder temps are playing a role. a lean condition would increase combustion temps and could lead to pre-det. the temp gage, at least reads well within the normal range in the afternoon. coolant level is fine. the gage seems to be functioning properly as it is low in the morning and climbs as the engine warms.

i will replace the plugs and wire this weekend. inspection of the plugs may give some indication of a lean condition. i will also do a comp check on each cylinder.

still no cel, any other thoughts on how to check for a lean condition or elevated operating temps?

 

[mrscullini]

one other thing, it only seems to happen at highway speeds. when going through the same rpm range at lower speeds the ping does not appear to be there.

 

[Big Jim M]

At hiway speed you reach maximum timing advance and maximum LEAN! Combined with just a little too much compression and you get a ping. Mayhaps there is a small amount of carbon built-up on the pistons.
Big JIm

 

[mrscullini]

At hiway speed you reach maximum timing advance and maximum LEAN! Combined with just a little too much compression and you get a ping. Mayhaps there is a small amount of carbon built-up on the pistons.
Big JIm

i changed the plugs yesterday, color looked okay, huge gap, maybe 075. plugs had 40k, they are autolite plats, ap5144, replaced with same.

checked the comp on each cylinder, ranged from 160 to 170. that seem good but not too high, 141k.

any thought, does this seem too high to others?

 

[Yellowsplash]

Higher octane is only a bandaid...seafoam treatments through the brake booster vacuum line, cleaning the MAF with CRCs MAF Cleaner, and setting the new plugs gap per specification are all good things to do. Where are you buying your gas from? Have you recently had any check engine lights? Also, might sounds dumb, but do you have an exhaust leak at the collectors? Many people mistaken this for knock under load...

 

[Guy]

I had the same problem with mine. Turns out my MAF was just plain worn out. I replaced the whole deal with a $15 junkyard MAF- off of a rolled rig with only 65k on the clock. Pingning went away. You could also try a lower heat range plug, if all the other suggestioins dont pan out.

 

[mrscullini]

Higher octane is only a bandaid...seafoam treatments through the brake booster vacuum line, cleaning the MAF with CRCs MAF Cleaner, and setting the new plugs gap per specification are all good things to do. Where are you buying your gas from? Have you recently had any check engine lights? Also, might sounds dumb, but do you have an exhaust leak at the collectors? Many people mistaken this for knock under load...

i realize the higher octane is not a permanent fix. that's a good call to change gas stations, i will give that a try. what is the typical replacement interval for a maf sensor? i don't think it is an exhaust leak but i will double check. no cel ever on this thing.

 

[289-tiger-]

I asked a mechanic iI knew that worked at Ford about cleaning the MAF. He just shook his head and also mentioned the Ford MAF replacement included a new connector due to resistance (still a mystery). The big box stores sell a very cheap rebuild(ran great during a 30 mile test drive after replacement, failed immediately the next day after startup, but finally threw a CEL). If you replace recommend a supplier such as NAPA or Carquest. It is worth the extra 30 dollars.

Also check all vaccum connections and torque on the lower intake.

Good luck, Sir.

 

[srteach]

I had the same tyO2 type problem on my 99 with the 4L OHV. changed the O2 sensors (all 3). Fixed. The front O2 sensors also adjust the air/fuel ratio.

 

[mrscullini]

I had the same tyO2 type problem on my 99 with the 4L OHV. changed the O2 sensors (all 3). Fixed. The front O2 sensors also adjust the air/fuel ratio.

did your o2 sensor problem throw a code and set the cel?

my cel is not on.