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Can't Get Rid of Engine Ping/Knock

Just throwing this out there... I've never gotten rid of my ping, just tamed it. Upper and lower intake gaskets, throttle body gasket, intake tube swap (and inspection), valve cover gaskets, timing gasket, timing set, new silicone vacuum hoses with minimal loops... Nothing's fixed it. I run premium gas and it doesn't ping 98% of the time. If I put regular in, it will ping on cold nights at highway speed on flat ground. I think some of us just have to deal with it, whether it's inherent to older computers, caused by carbon build up or a worn engine.
Yes, I am resigned to the fact that the pinging may be caused by different issues combined, or individually at different times, depending upon conditions. The computer is old, software is old, engine is old, seals are old, everything is just old...lol! Still, I'm hoping that maybe I will find something that when fixed or changed, will make it much less of an issue. I would love to be 98% ping free. That would be amazing. Thanks for the info!
 



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Could somebody clarify what you guys mean by pinging? Am I right in saying this is the same as knocking/detonation? What exactly are you guys heading to indicate this is occurring? I'd just like to know the telltale signs. Thanks in advance.
 






Could somebody clarify what you guys mean by pinging? Am I right in saying this is the same as knocking/detonation? What exactly are you guys heading to indicate this is occurring? I'd just like to know the telltale signs. Thanks in advance.[/QUOTE
Yes, when I refer to pinging, I am talking about engine knock, or pre-detonation. Just another word for the same thing. It is caused when the air/fuel mixture ignites unevenly in the cylinder, after the initial ignition spark. The telltale sign is loss of power, and the uneven rattling sound; also called pinging, marbeling (sounds like marbles ratteling around in the cylinder, or deaseling. In addition to being really annoying, it can cause damage to the piston and cylinder walls, which can be an issue with the 4.0 engines, as they have been bored out so much to reach this displacement from an original engine displacement of 2.5 liters (I think this is correct).
 






I think I have fixed the problem, thanks to Rhett's suggestions and info! I will do my best to explain, as I haven't figured out how to upload photos to this site yet.

I removed the intake tube and the rubber seal on the throttle body side. The rubber seal was all chewed up on the bottom, and a large chunk of the plastic intake tube was missing from the end in the same spot the rubber seal was damaged. I believe this allowed unmetered air to enter the intake and leaned out the fuel/air mixture, which can cause ping/knock.

I removed the seal and cleaned up the end of the tube, removing grease, dirt, and oil from the outside and inside. I abandoned the rubber seal. I cut a 3.5" x 11.5" piece of foil covered *****ithane roofing membrane from a spare roll I had (you can get it from Home Depot). I peeled the protective cover from the *****ethane and used a heat gun to warm it up, along with the end of the intake tube. I then wrapped the *****ethane around the end of the tube once, about 1.75" from the end of the tube, with about a 1/2" overlap. I then pressed it down tight around the outside of the tube. I heated up the exposed inside of the *****ethane and intake tube again, and then folded the *****ethane down around the inside of the tube as far as it would go (about 1.75"). This replaced the rubber seal. I put some silicone lubricant around the inside and fitted the tube back in place and clamped it down with the original clamp ring. Perfect seal! I did a 10 mile test drive on the highway and through town; up and down hills and flats, through all gears. Zero ping/knock! I'm not sure how well the *****ethane will hold up over time, but it's fairly strong and sticky stuff when applied warm, to a clean surface. I will add photos if I can figure out how upload them. Thanks Rhett!
 






Glad you got it fixed , that's what this forum is for . this is the best forum i have ever seen .
 






I'm glad that solved it. I'm not familiar with this "*****ethane" roofing membrane you mention...I'll have to look it up, I'm always game for new ways to fix things.
 






I'm glad that solved it. I'm not familiar with this "*****ethane" roofing membrane you mention...I'll have to look it up, I'm always game for new ways to fix things.
It's a heavy flashing material, and can be used on roofs and around door and window rough openings. It's a sticky tar based material with a heavy backing, either plastic or aluminum. It's peel and stick, but I usually hear it up to improve adhesion. Not sure how well it will hold up long term, but I will find out. Thanks again!
 






So unfortunately I spoke too soon.... I thought the knock issue was resolved after repairing the intake tube at the throttle body, but unfortunately knock is back worse than ever (it has gotten really bad). I have found that when the engine starts out cold, it runs just fine, and does so for about 30-40 minutes, even after the engine warms up, but is not hot. However if I am on a long drive and gets hot, or I park for a while and then start driving again, the knock starts, and gets really bad when both climbing hills and on the highway, starting at about 2k rpm. If I go full throttle, and the rpm's jump, as if passing, the knocking almost goes away. So as I try to diagnose and fix this, I have a few questions I am hoping someone can answer:

1. Could this be caused by one or more bad injectors or a fuel pump issue?

2. Could it be caused by a failing O2 sensor? I don't really know if the O2 sensor has any affect upon the fuel/air mixture, but if it does, could it be causing it to be overly lean?

3. It has been suggested that it may be a bad upper or lower intake manifold gasket or a stretched timing belt. I'm not sure if the fact that there is no knock when the engine is cold/warm (not hot) would rule these out?

4. I have replaced the ECT sensors recently, but are there any other sensors on the engine that could be the cause?

5. I am slowly loosing coolant; 2-3 cups per week, and haven't yet found the leak, but suspect it could be coming from where the upper radiator hose connects to the neck of the thermostat housing. If this isn't the cause of the coolant loss, could a failing head gasket or manifold gasket be allowing coolant into the cylinders and causing knock?

I know this is a lot to ask, but any info or suggestions would be appreciated!
 






Just for reference this product is made from Bituthene.
It can be hard to work with, hence the common trade name.
 






Just for reference this product is made from Bituthene.
It can be hard to work with, hence the common trade name.[/QU
Thanks!
Just for reference this product is made from Bituthene.
It can be hard to work with, hence the common trade name.
Thanks! Should have checked the spelling first!
 






Is your EGR system functioning? Any check engine light with EGR codes?
 






Is your EGR system functioning? Any check engine light with EGR codes?
Yes, I ran a KOEO test and pulled three continuous codes, 172, 332, and 556, but no KOEO codes, other than the 111 pass code. The 332 is an insufficient EFR flow detected code. I removed the MAF yesterday and gave it another good cleaning, and no knock. However, my check engine light did come on for a few seconds twice yesterday and then went off again. I will re-run the KOEO today and also run a KOER test.
 






Yes, I ran a KOEO test and pulled three continuous codes, 172, 332, and 556, but no KOEO codes, other than the 111 pass code. The 332 is an insufficient EFR flow detected code. I removed the MAF yesterday and gave it another good cleaning, and no knock. However, my check engine light did come on for a few seconds twice yesterday and then went off again. I will re-run the KOEO today and also run a KOER test.

If you have insufficient EGR flow code, I'd say your EGR is not functioning as designed and that is another big cause of ping in the 93.5-94 Explorers
A poor flowing EGR will result in higher combustion temperatures and that increases the chances of pinging.

On my truck the upper intake manifold port leading to the EGR was clogged with carbon. i had to remove the upper intake manifold and clean it thoroughly. Of course, there could be actual components of the EGR system failing, but on my truck it was simply carbon buildup.
 






Sometimes the "pinging" that these engines have at high mileage is caused by the wear on the stock rocker arms, and if the rocker arm wear gets bad enough, it can affect the lifters, requiring replacement of both:

http://www.explorer4x4.com/lifters/lifters.htm


Actual engine knock, like hard, violent knock under hard acceleration, sometimes is the fuel injectors. Years ago I had consistently put in cheap gas back when Sam's/Wallyworld was selling the stuff without enough detergent in it, and it apaprently eventually did a number on the injectors, to the point that when I hit the gas, the knock felt like a giant hammer was hitting the engine block from the passenger side with each piston stroke, hard enough to shake the entire vehicle. The fix was a few bottles of STP fuel injector cleaner over the next few fillups, followed by consistent use of Chevron with Techron over the next several weeks/months. The knock subsided and eventually disappeared altogether. These days I only use top tier gas( http://www.toptiergas.com/licensedbrands/ ) and I haven't had a similar issue since.

I'd say it's definitely worth a shot using some brand-name top tier 87 octane fuel over no-name high-octane. It may not fix it quick, but if that is the issue, you'll be on the way to solving it rather than perpetuating the problem by using the fuel that's causing it in the first place.
 






Sometimes the "pinging" that these engines have at high mileage is caused by the wear on the stock rocker arms, and if the rocker arm wear gets bad enough, it can affect the lifters, requiring replacement of both:

http://www.explorer4x4.com/lifters/lifters.htm


Actual engine knock, like hard, violent knock under hard acceleration, sometimes is the fuel injectors. Years ago I had consistently put in cheap gas back when Sam's/Wallyworld was selling the stuff without enough detergent in it, and it apaprently eventually did a number on the injectors, to the point that when I hit the gas, the knock felt like a giant hammer was hitting the engine block from the passenger side with each piston stroke, hard enough to shake the entire vehicle. The fix was a few bottles of STP fuel injector cleaner over the next few fillups, followed by consistent use of Chevron with Techron over the next several weeks/months. The knock subsided and eventually disappeared altogether. These days I only use top tier gas( http://www.toptiergas.com/licensedbrands/ ) and I haven't had a similar issue since.

I'd say it's definitely worth a shot using some brand-name top tier 87 octane fuel over no-name high-octane. It may not fix it quick, but if that is the issue, you'll be on the way to solving it rather than perpetuating the problem by using the fuel that's causing it in the first place.
Yes, I am guilty of bargain shopping for gas, and am now paying the price I think. I'm using top tier now. I have heard the Shell has the most additives, but haven't confirmed it. I'm pretty sure I am experiencing true knock, rather than lifters, but I can't say 100%. It's intermittent, and with 225k, it could be caused by several things; EGR, injectors, carbon, Bad sensors, etc. Using better fuel and adding some bottles of injector cleaner is easy and won't hurt! Thanks!
 






Pardon the slight hijack to your thread, but I wanted to post that I repaired the cracks and holes on my intake tube that I mentioned earlier. I took Rick's suggestion and used silicone tape. Cost less than $5 and was super easy to do, even though the damage was all on the accordion pleats. I disconnected the battery afterward so the computer would relearn with the correct air mixture, and so far I have no more ping/popcorn!
This was the worst damage, it's the intake manifold end, the other end was just cracks in the pleats. All damage was on the underside of the tube and could not be seen at all when tube was in place. From a casual glance under the hood, the tube looked to be in perfect condition, other than the dirt.

IMG_6453.JPG
 






When the gasket went bad on my old intake, I used a section of a bicycle tire inner tube. Stretched two layers over the intake and new gasket. Worked great.
 






I think if you're losing coolant and don't see any puddles, head gasket could be the culprit. I dealt with that anyway. Are you losing oil or have to top it off well before 2k miles? Piston rings could be letting oil up into the combustion chamber allowing an additional propellant in to burn; also creating carbon deposits. That would definitely make it a lot hotter down there. Maybe put on a backwards facing cowl on the hood to keep hot air sitting at the top of the engine flowing would drop under hood temps.
 






Pardon the slight hijack to your thread, but I wanted to post that I repaired the cracks and holes on my intake tube that I mentioned earlier. I took Rick's suggestion and used silicone tape. Cost less than $5 and was super easy to do, even though the damage was all on the accordion pleats. I disconnected the battery afterward so the computer would relearn with the correct air mixture, and so far I have no more ping/popcorn!
This was the worst damage, it's the intake manifold end, the other end was just cracks in the pleats. All damage was on the underside of the tube and could not be seen at all when tube was in place. From a casual glance under the hood, the tube looked to be in perfect condition, other than the dirt.

View attachment 150437
Wow, that hole was probably good for a few extra CFM of unmetered air! Let us know how the tape holds over the next few weeks.
 



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Will do. I'm hoping for the best, as it's advertised to be good up to 500 degrees. But at $5 a roll, I won't mind redoing it every so often if it doesn't last.
 






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