Pinging on Hills

[FourBinLabs]

I could be way out of bounds here, being as my mounty is a bit newer. Is this vehicle waste spark? If so, it would spec double platinum plugs right?

Not that it has anything to do with the pinging, just wanted to bring it up.

 

[lobo411]

I could be way out of bounds here, being as my mounty is a bit newer. Is this vehicle waste spark? If so, it would spec double platinum plugs right?

Not that it has anything to do with the pinging, just wanted to bring it up.

Ya, I read somewhere else that these are supposed to have double plats. I've been running single plats for 10 years w/o issue, but it was cheap enough to give the doubles a shot so I did. No joy, though. Thanks for the suggestion, though!

 

[rb142]

You've probably run enough Techron (and other things) through already. There is a limit to how much those products will do. If there is a lot of carbon buildup, there may be a more effective cleaning system at a mechanic near you ... but you may not find it worth the cost to try it.

Have you reset the PCM (pulled the power) since the other repairs? I guess you said you ran up some miles at least -- enough to re-adjust the trims. (I'm thinking about whether the other issues may have messed up the mixture or timing.) I wonder what the knock sensor is doing during all this? I'm assuming this happens before you get to full WOT.

You are sure it is pinging right, and not something else? It probably is, but...

 

[lobo411]

You've probably run enough Techron (and other things) through already. There is a limit to how much those products will do. If there is a lot of carbon buildup, there may be a more effective cleaning system at a mechanic near you ... but you may not find it worth the cost to try it.

Have you reset the PCM (pulled the power) since the other repairs? I guess you said you ran up some miles at least -- enough to re-adjust the trims. (I'm thinking about whether the other issues may have messed up the mixture or timing.) I wonder what the knock sensor is doing during all this? I'm assuming this happens before you get to full WOT.

You are sure it is pinging right, and not something else? It probably is, but...

Ya, the PCM has had a chance to reprogram several times (had to pull the battery to do some of the repairs). I did have an issue with the DPFE sensor for several years (common problem--intermittent failure resulting in EGR insufficient flow code, but a new sensor resolved the issue), and my oxygen sensors were pretty weak so the engine mix might have been off for years.

That's interesting about the WOT. It pings the worst when I'm on a grade attempting to maintain cruising speed, either in Overdrive or not. It seems to ping less/stop pinging if I mash the gas and go to WOT. I'm not sure how or why, though.

I'll see if it pings this Wed. Where I live is pretty flat, but there's a 1500' hill between here and work. That's usually where it pings. I filled up with premium this time, so we'll see.

 

[FourBinLabs]

That's interesting about the WOT. It pings the worst when I'm on a grade attempting to maintain cruising speed, either in Overdrive or not. It seems to ping less/stop pinging if I mash the gas and go to WOT. I'm not sure how or why, though.

I'll see if it pings this Wed. Where I live is pretty flat, but there's a 1500' hill between here and work. That's usually where it pings. I filled up with premium this time, so we'll see.

I would imagine that mashing the gas is probably unlocking your TC or causing a downshift (probably both). Higher RPM reduces chance of detonation.

I have not solved why my pickup truck started pinging a while back, although I expect a lean condition, and have been running 93 octane ever since. If I ever get out on the highway and give it WOT with 89 octane, it will usually be OK when the engine is wound up, but will ping the most during, or right after a shift.

 

[lobo411]

I would imagine that mashing the gas is probably unlocking your TC or causing a downshift (probably both). Higher RPM reduces chance of detonation.

I have not solved why my pickup truck started pinging a while back, although I expect a lean condition, and have been running 93 octane ever since. If I ever get out on the highway and give it WOT with 89 octane, it will usually be OK when the engine is wound up, but will ping the most during, or right after a shift.

Ya, I ran Premium on this trip and it didn't ping. I'm guessing that this has something to do with the additional oil I've been burning. I used to burn practically no oil between oil changes, and now I burn about a quart every 1200 miles. I still have a slow external leak somewhere (rear main maybe) so maybe I'll just try a stop leak and Techron.

 

[rb142]

Oil in the cylinder can in fact create more pinging (tiny oil droplets can create additional sources of combustion). This is a possibility, considering the potentially worn out rings, as per your other thread. Another reason to do the compression test.

 

[lobo411]

Couldn't find the compression tester, but I did notice that it doesn't ping when I use Lucas Oil Upper Cylinder Lube in the gas. It's not a permanent thing--it goes back to pinging as soon as the Lucas stuff runs through the tank, but I guess 1/2 cup of oil per tank is something I can live with. Weird though. I can't see how what amounts to glorified oil in the gas can help prevent pinging.

 

[rb142]

Because glorified oil does the same thing as higher octane gas and reduces pre-ignition. Cheaper and easier to just use the higher octane gas.

 

[koda2000]

when an engine gets a lot of a miles on it, especially if it's burning oil, it accumulates carbon and other residue in the combustion chamber. this build-up effectively increases the engine's compression. that's why you get pinging (aka pre-ignition) when the engine is under load. higher octane fuel has additives in it to make the fuel more stable and less prone to pre-ignition in higher compression engines. most engines today have knock sensors. their purpose is to sense pinging and retard ignition timing slightly in an effort to eliminate pre-ignition. apparently you are now beyond the point where retarding timing is enough. i gotta agree with rb142. just step up to a higher octane grade of fuel instead of putting additives in the cheaper grade.

 

[deadernie]

How old are the coils? I replaced the plugs, wires, and coils in my Ranger. Aftermarket coils though and started pinging unless I ran 93 octane. Got a Motorcraft coil and went back to regular gas.

 

[lobo411]

How old are the coils? I replaced the plugs, wires, and coils in my Ranger. Aftermarket coils though and started pinging unless I ran 93 octane. Got a Motorcraft coil and went back to regular gas.

They're the OEM coils, so 16 years old. Was yours pinging all the time, or just occasionally? I might try that since I've tried everything else, but I'll probably wait until after May (if it fails smog, then I might just give up on it).

 

[lobo411]

when an engine gets a lot of a miles on it, especially if it's burning oil, it accumulates carbon and other residue in the combustion chamber. this build-up effectively increases the engine's compression. that's why you get pinging (aka pre-ignition) when the engine is under load. higher octane fuel has additives in it to make the fuel more stable and less prone to pre-ignition in higher compression engines. most engines today have knock sensors. their purpose is to sense pinging and retard ignition timing slightly in an effort to eliminate pre-ignition. apparently you are now beyond the point where retarding timing is enough. i gotta agree with rb142. just step up to a higher octane grade of fuel instead of putting additives in the cheaper grade.

Interesting...I guess the snake oil stuff is just oil, and oil is harder to burn than gasoline, so that's why it stops the ping? Just kind of ironic that oil might be causing the problem (carbonization) and oil is also a palliative for the problem.

I'm not sure if the 1996 4.0 OHV has a knock sensor...I'd replace it if I could find it, because I'm not getting any codes.

 

[DoraThe_Explorer]

^^^ I am 99.9% sure the OHV doesn't have a knock sensor, but the SOHC does.

 

[lobo411]

Semi-update: I ended up buying a new Ford Focus to use as my commuter car, but I'm keeping the Explorer as an around-town car/moving van. I only commute 1 day a week, so this means I'll still be driving the Explorer the rest of the week but only putting 10 miles a day on it. I'm hoping this gives me the best of both worlds--most of the abuse (moving cargo, short-haul driving, getting into the car in my sweaty gym clothes, etc...) goes to the old car, and the important stuff (getting to work) goes to the new car. Plus I can work on the Explorer at my leisure.

I just hope I didn't make a mistake in keeping it. I didn't trade it in because I thought if it failed smog, worst case I could retire it for $1500 w/ the gov't. But it turns out that that program only applies to cars that have clean titles, so the best I could do would be to scrap it if it becomes unsellable (can't sell it if you can't smog it).

So I kind of have to fix the pinging because my theory is that it's related to the high NOx that almost caused me to fail smog 2 years ago. I ordered a hand vacuum pump to give the EGR valve a real test. I have no codes, but I thought the two symptoms (pinging and high NOx) are said to be related to the engine running too hot, and the EGR is supposed to cool things down.

 

[FourBinLabs]

Hi NOx and Pinging are usually both related to a lean condition or over-advanced spark.

If you end up finding a vacuum leak and fix it to bring down the NOx, you may actually fix the pinging as well.

 

[lobo411]

K of all the threads I started trying to get this car past smog, this one seems the most relevant. I'm pretty sure the car still pings on big hills, but since I no longer go on big hills (bought a new Ford Focus for commuting), it's not a big deal anymore. I still needed to get through smog, though. So here's what I did, over the last 6 months:

Replaced:
plug wires
plugs
several vacuum lines (not voluntarily...I broke a few of em)
radiator flush
lower intake manifold gasket
fuel rail gasket
upper intake manifold gasket
cleaned MAF + IAT sensors
ran several tankfuls of Techron
ran rislone oil cleaner, then drained oil and installed rislone compression restorer, then changed oil and ran plain oil for the test

Also, I replaced the gas cap at the smog check station b/c I would have failed with the OEM one. I had been thinking of replacing it anyway because I was getting an occasional gas cap code despite being certain I had put it on right.

Passed!

Results from 2012:
15 MPH: ..................................25 MPH
co2=6.5% ................................6.5%
o2=11.5%.................................11.4%
HC: 32 PPM (fail = 47).................16 (fail = 31)
co: 0.3% (fail = 0.6)....................0.29 (fail = .73)
nox: 493 PPM (fail = 494).............365 (fail = 747)

This year:
15 MPH ....................................... 25 MPH
co2 = 9.2%.....................................9.1%
o2 = 7.7%......................................7.8%
HC = 39 (fail = 47)..........................10 (fail = 31)
co = 0.18% (fail = .6%)..................0.24 (fail = 0.73%)
noX = 269 (fail = 494) .....................50 (fail = 747)

So my noX went way down, but my HC is creeping up a little. I'm guessing that's due to the internal oil leak I've been having for the last 2 years. It was burning 3/4 quart every 1000 miles. But I think there's not really anything that can be done about that. Glad to see the Nox dropped so precipitously!

 

[rb142]

Congratulations!

 

[lobo411]

Congratulations!

Thanks! When I bought the Focus I passed on a trade in + $500 trade in bonus cash in favor of keeping the Explorer. I figured they'd only offer me a few hundred or maybe $1k for the X, and it was worth more than that to me as an around town car/utility wagon/camper. Imagine if I had passed on that $1k-$1500 only to have to pour $$ into it to get it past smog!

 

[FourBinLabs]

I don't think I'd worry about your HC numbers going up. It looks like you fixed a vacuum leak to me.

Your NOx numbers were way high last time (one ppm from failing at 15 MPH). Seeing the NOx and O2 come down like that says that the car is not running as lean any more. It will always be a sliding scale. As NOx comes down, HC will go up. I would have expected CO to go up too, but that could be that your cat is working better now, or was warmer at the time of the test and converting to more CO2.

I know of guys that have intentionally created small vacuum leaks in order to lower their HC and CO numbers in order to pass the test, as long as they had enough margin on NOx to get away with it, it worked fine. Not necessarily encouraging this, just sharing.