pinging on ethanol?

[jmmctighe]

I seem to be having a pinging problem on my '00 OBW. I currently have 76K on it and plan on doing a tune up since I'm not exactly sure what the dealer did prior to my purchase. They claim the plugs were changed @ 60K and wires don't need to be done until later....I've always replaced wires by then. I did change the air filter and recently did an oil change with castrol syntech (not that the oil matters but I want to show I'm keeping up with maintenance).

Anyway, is one effect of ethanol a ping on light acceleration or going up steady inclines? I've used 87 and 89 octane, added a big bottler of techron, and even with the techron, I still had the ping.

Any advice?

 

John

[nipper]

I seem to be having a pinging problem on my '00 OBW. I currently have 76K on it and plan on doing a tune up since I'm not exactly sure what the dealer did prior to my purchase. They claim the plugs were changed @ 60K and wires don't need to be done until later....I've always replaced wires by then. I did change the air filter and recently did an oil change with castrol syntech (not that the oil matters but I want to show I'm keeping up with maintenance).

Anyway, is one effect of ethanol a ping on light acceleration or going up steady inclines? I've used 87 and 89 octane, added a big bottler of techron, and even with the techron, I still had the ping.

Any advice?

 

John

 

Thats just normal ping, some engines do it some dont. You can try a cooler plug, check the knock sensor, egr valve, but sometimes ping is just ping.

 

nipper

[Schwinnbob]

Hi:

 

I have the same pinging in my 00 also. I have been using Shell premium which greatly reduces (almost eliminates) it but also greatly reduces the thickness of my wallet. But for me it's worth it to not hear the ping. Changing the plugs and wires ( Subaru OEM) did nothing to reduce the ping. I agree that colder plugs would likely help.

[brus brother]

I m using an NGK plug BKR7E11, one step colder than spec on my 2000 and the change is marginal if at all noticeable. Is this a MY 2000 thing or are other years experiencing the same ping under light acceleration? Mine is more noticeable during the summer months.

Hi:

I have the same pinging in my 00 also. I have been using Shell premium which greatly reduces (almost eliminates) it but also greatly reduces the thickness of my wallet. But for me it's worth it to not hear the ping. Changing the plugs and wires ( Subaru OEM) did nothing to reduce the ping. I agree that colder plugs would likely help.

[nipper]

I m using an NGK plug BKR7E11, one step colder than spec on my 2000 and the change is marginal if at all noticeable. Is this a MY 2000 thing or are other years experiencing the same ping under light acceleration? Mine is more noticeable during the summer months.

 

Varies literally between individual cars and individual brands, weather conditions etc etc

 

 

nipper

[brus brother]

As you know Nippy, I've been after this since 99 :horse:when I bought the 00 new. The other two current posters on this issue are 00 owners and I am trying to determine if a pattern exists at least in this micro-group of 00 owners. I've had other cars ping before under heavy and hard acceleration but this is different and Subie techs who have worked on solving the problem scratch their heads when I come by (they don't seem to be inclined to accept SOA's "normal" condition explanation). The latest suggestion is a lower temp thermostat but as in the case of using cooler plugs, I question going out of spec since it is only noticeable when ambient temp is above 60F and possibly? humidity related.

Varies literally between individual cars and individual brands, weather conditions etc etc

 

 

nipper

[jmmctighe]

Well, I just filled with 93 octane from Mobil and though the ping is lessened, it is still there. I'd think at 93 octane there shouldn't be any pinging whatsoever (I'd also think this on 87 for any well running, good condition vehicle). Hell, the 95 LS I traded in with 170K NEVER pinged on cheepie gas. Can't say I'm thrilled.

I think I'll need to look elsewhere, perhaps a vacuum leak or....I dont know, its just frustrating. Having worked on cars all my life I would never accept tht a ping is normal. Anyone know of a way to modify the timing w/o use of a replacement chip?

 

The reason I started the post was that when I asked the Service dept about this they claimed it was the ethanol causing the increase in ping and hesitation complaints they've received. As I look on this forum there doesn't appear to be many, if any, ethanol realted issues on this.....interesting. Is this just another convenient excuse used by the service dept?

 

John

[nipper]

no two cars are exaclty alike when it comes to ping. There are common things to check. You make sure the EGR valve is operating properly, make sure the knock sensor is good (this is a knock sensor not a ping sensor), and make sure you have a good t-stat. The other thing you can do is try a vooler spark plug from the same mfg as is already in the car. Ping is a very complicated thing, and it is not considered abnormal, as annoying as it is. Cars run very lean, which menas higher combustion temps. The spark plug housing retains this heat, hence you have ping. Knock which is caused by bad timing, a engine funning hot, poor oil pressure (oil does cool the pistons) and excessive carbon buildup in the engine is bad. Carbon buildup isnt as bad a problem as it used to be due to better fuel control (super lean engines). Also something as simple as having the AC on can cause ping while having it off does not. This is within the acceptable range.

 

nipper

[NorthWet]

... make sure the knock sensor is good (this is a knock sensor not a ping sensor)...

Would you please clarify your distinction between knock and ping? (I know how I define them. )

[nipper]

Would you please clarify your distinction between knock and ping? (I know how I define them. )

 

ping si that popcorn sound you sometimes hear under light acceleration. This ping is caused by too hot a spark plug, and is annoying. Knock is a much more deeper sound, and you can actually feel the cars performance suffer. Its hard to explain without pointing out the sound. knock is also much louder then ping.

 

nipper

[jon38iowa]

ping si that popcorn sound you sometimes hear under light acceleration. This ping is caused by too hot a spark plug, and is annoying. Knock is a much more deeper sound, and you can actually feel the cars performance suffer. Its hard to explain without pointing out the sound. knock is also much louder then ping.

 

nipper

Hello,

You might consider having the engine cleaned ( flushed internally) . Its possible your engine has carbon build up on the pistons, and having this cleaned might eliminate the Ping; It made quite a difference on my Forester.

John

[NorthWet]

ping si that popcorn sound you sometimes hear under light acceleration. This ping is caused by too hot a spark plug, and is annoying. Knock is a much more deeper sound, and you can actually feel the cars performance suffer. Its hard to explain without pointing out the sound. knock is also much louder then ping.

 

nipper

I beg to disagree with your understanding of this. Too hot of a spark plug will cause preignition (somewhat by definition); preignition will cause some loss of power, increase in engine temps, and a predisposition to detonate. Detonation is the uncontrolled, rapid, abnormal combustion of the combustion chamber's endgas (that part of the mixture furthest from the point(s) of ignition). Pinging and knocking are 2 interpreted variations of detonation, depending on how much endgas is involved. Detonation is common, preignition is not, but they both can feed an escalating cycle of each other.

 

Almost by definition, an engine's combustion is at its most efficient when right at the edge of detonation, so most modern cars are tuned to be on the edge. It is common for engines to ping (detonate) lightly under load as the engine management tries to walk the line. By lightly, I mean a couple pings interspersed over a second or two.

 

Any oil in the intake mixture will greatly increase the likelyhood of detonation, as oil is less stable in the endgas and will degrade quickly into lower flashpoint molecules.

 

A knock sensor senses all vibrations, and its controller looks for signals with very rapid rise and fall times and a certain threshold amplitude. The knock sensor may be failing to produce sufficient signal amplitude for the controller to think the pinging is a problem. Or, everything is working as it should.

[nipper]

I beg to disagree with your understanding of this. Too hot of a spark plug will cause preignition (somewhat by definition); preignition will cause some loss of power, increase in engine temps, and a predisposition to detonate. Detonation is the uncontrolled, rapid, abnormal combustion of the combustion chamber's endgas (that part of the mixture furthest from the point(s) of ignition). Pinging and knocking are 2 interpreted variations of detonation, depending on how much endgas is involved. Detonation is common, preignition is not, but they both can feed an escalating cycle of each other.

 

Almost by definition, an engine's combustion is at its most efficient when right at the edge of detonation, so most modern cars are tuned to be on the edge. It is common for engines to ping (detonate) lightly under load as the engine management tries to walk the line. By lightly, I mean a couple pings interspersed over a second or two.

 

Any oil in the intake mixture will greatly increase the likelyhood of detonation, as oil is less stable in the endgas and will degrade quickly into lower flashpoint molecules.

 

A knock sensor senses all vibrations, and its controller looks for signals with very rapid rise and fall times and a certain threshold amplitude. The knock sensor may be failing to produce sufficient signal amplitude for the controller to think the pinging is a problem. Or, everything is working as it should.

 

Technically knock and ping are two seperate animals. Ping can lead to knock, but not always.

http://www.factorypipe.com/Technical/Tech_Articles/Deto/deto.html

 

knock sensor can not compensate for unctrlled ignition. Light ping is not desirable but acceptable, and in comparison to knock is not a huge prioblem. Also changing where you buy gas may help. Another poassability is the timing belt getting a little sloppy. There are many many reasons for ping, unfortunitly. You can try decarbonizing the engine. You can try a cooler thermostat.

Once you go over the major things, sometimes there is no solution for it. Ping under light throttle isnt all that bad, ping under heavy throlle, ot that does not go away when the humidity or weather changes is bad.

 

http://www.chevrolet.com.au/articles/knock.html

http://www.misterfixit.com/deton.htm

 

something else i found

 

 

Exhaust Gas Recirculating Valves

What are they? What do they do? How do they fail??

EGR Valves have been around for a long time. Way back in 1972 GM used them in an attempt to reduce emissions of oxides of nitrogen (NOx) which were a major cause of air pollution, mainly photochemical smog, that kind of smog which is formed when strong sunlight shines down on the exhaust gasses we puke out of our tailpipes by the billions of cubic feet a day.

 

A short chemistry lesson is in order here. It was discovered way back when, that high combustion chamber peak temperatures (the really short duration high temperatures near the end of the combustion process) caused oxygen and nitrogen to combine chemically and form these oxides of nitrogen mentioned above. Most of the anti-pollution devices of the day did a pretty good job of reducing the other bad by-products of combustion, namely excessive hydrocarbons and carbon monoxide, however they tended to induce the formation of oxides of nitrogen. Something had to be done else we would all die of smog diseases.

 

The automotive engineers figured that they needed to do something to lower the peak combustion temperatures which only occurred under certain high load driving conditions. They figured they could do so at the expense of power and fuel economy but what the heck, ya can't have everything! If they could only add something to the combustion chamber that would act like sort of a fire extinguisher to cool the combustion temperatures that would do it.

 

So they invented a way to allow some very inert gas to get back into the combustion chamber only when needed. They needed a source of this gas - it wasn't air, cuz that contains oxygen and nitrogen which caused the problem in the first place. So they chose carbon dioxide. Where to get a supply of carbon dioxide . . . ??? Hmmmm, how about the exhaust system? That is mainly carbon dioxide and water (plus a zillion other noxious chemicals) Suppose we allow some of the exhaust gas to get back into the intake manifold under strict control and only when we need it? That would cool the combustion chamber and prevent the formation of the NoX. Maybe we should call it recirculated exhaust gas (REG??). But a guy named Reginald voted no cuz he didn't want his name associated with a car part, so they called it exhaust gas recirculation (EGR) since there was nobody around with that name.

 

Now we understand why it is there. And we understand what it does. So what can go wrong with it and what are the symptoms??

 

It's really pretty simple - it can be open when it isn't supposed to be, or it can be closed when it is supposed to be open. Not rocket science, but it is science. If it is open when it is not supposed to be open, at idle for instance, It will act like one monster vacuum leak and the engine will not idle or will idle really roughly. If it doesn't open when it is supposed to open you will probably experience a symptom of "pinging" or "knocking" since the combustion chamber temperature will be higher than normal (one of the main causes of pinging in an engine).

 

There are a zillion different types of EGR valves some of which work strictly on vacuum, and some which work on a combination of vacuum and pressure. Some have electronic controls, some have mechanical controls. I won't go into detail here about all the different types but suffice it to say that most can be checked by looking inside to see if the plunger shaft is stuck open or doesn't move when the engine is revved up (after it is warmed up). Replacement is probably the easiest part since most are held in by two small bolts and have a vacuum line connected to it. The hard part is whipping out your Visa card to pay for it since most of them will drain your reserves in a hurry!!

[hotrod]

As I look on this forum there doesn't appear to be many, if any, ethanol realted issues on this.....interesting. Is this just another convenient excuse used by the service dept?

 

Ethanol should not have anything to do with your engine ping.

The ethanol is an octane improver, when added to gasoline its blending octane is 118.

 

We have been using ethanol blended gasolines in Denver Colorado for almost 30 years --- it does not cause ping.

 

 

Ping and Knock are different terms for "the same effect"!

Ping is light detonation,at high rpm, Knock is heavy detonation at low rpm.

(in europe ping is known as "pinking")

Same thing, same cause, only difference is the severity.

 

Pre-ignition and knock (detonation) are different but closely associated effects, and frequently occur together.

 

Pre-ignition occures when the fuel air mixture is ignited prior to the spark, usually due to a hot spot in the combustion chamber, ie carbon build up etc.

 

Detonation occurs late in the combustion process when the end gases that have not completely burned spontaneously detonate due to high temperatures and pressures.

 

A very large amount of information out on the internet regarding detonation/knock/or ping is either bad or flawed. It is a very complex subject and even after nearly a century of research is not completely understood.

 

Some of the best research on knock was done near the end of WWII for high performance military aircraft and the reports available on the subject would fill a small book. Many of the lessons learned during that research are still the best available info for application to performance automobile engines.

 

Larry

[BigMattyD]

Recently, I drove from my home to Columbus, OH, and stopped at a gas station where their gas was 10% ethanol, and I swear I heard pinging, when normally I never do. It went away now that I'm back home...

 

Matt

[nipper]

Is it just me, but i dont get the big deal about ethanol. In NY we have had ethanol in our fuel since i guess the 1980's.

Ping is very sensative to air temp humidity altitude and load on the engine (head vs tail wind). Just because you hear it in one place doesnt mean you have it.

This is getting to be one of those i may just bow out of, since no one has engine knock. Ping is just due to the fact that engines run at the stochiomteric ratio, and therefor run very hot inside the combstion chambers.

All cars ping once in a while, and here's another thought. Just because you cant hear it doesnt mean its not happening.

Ping happens before TDC, knock happens after tdc. Ping happens as the air fuel mix is being compressed, usually after the spark plug has fired. It starts another flame front due to a hotspot in the cylinder, its not a godd thing, but its also not horrible, just anoying.

Knock is the air fuel mix getting ignited after tdc, as it starts to enter the cylinder. This is very yery bad. As the piston starts to go up on what should be a compression cycle, it has an uncontroled explosion on which it has to fight again. PING = Pre ignition is just that. Its happening in the 15-35 degrees before tdc, where normal combustion takes place to begin with. Knock is happening usually 280 degrees before TDC which is very very bad, this is what blows up a piston.

 

nipper

 

(hope that helped)

[hotrod]

PING = Pre ignition is just that.

 

Sorry ping is not pre-ignition.

 

ping is simply knock (detonation) that happens at high rpm, when knock occurs at low rpm it changes sound to a heavy rattle, knocking sound. They are both the same thing but occuring under different conditions.

 

"If" you hear pre-ignition which is very rare it causes a low rumbling sound that is hardely detectable, but is very quickly fatal to the engine.

 

It starts another flame front due to a hotspot in the cylinder

This is pre-ignition due to a hot spot, not ping.

 

There are actually several different intensities of knock, light, moderate and heavy. Some engines can tolerate light knock(ping) almost indefinately, moderate knock if brief "usually" does little harm. Heavy knock, is very hard on an engine and quickly damages bearings and pistons or blows head gaskets.

 

If you look at a pressure trace of a cylinder that is knocking (pinging) you will see that the cylinder pressure rises smoothly much like it does under normal condtions until just before TDC, then the rate of pressure change increases faster than normal. Shortly after TDC there is a sharp pressure spike which creates a powerful shock to the top of the piston in a time interval of about 1/20000 of a second, as the detonation occurs, followed by a high frequency ringing (which gives light knock its pinging sound). That ringing sound is a characteristic of the bore size of the engine. Large bore engines have a lower pitch compared to a small bore engine.

 

Pre ignition is just that. Its happening in the 15-35 degrees before tdc

 

That is the time interval that "normal" ignition takes place.

 

Knock is happening usually 280 degrees before TDC

That is incorrect this would be on the intake stroke, as the compression stroke only lasts 180 degrees of crankshaft rotation (actually less since the intake valves close when the piston is already moving up the bore).

 

 

Unfortunately there is a "HUGE" amount of bad info out there on detonation.

Not picking on anyone here, but just trying to correct some misunderstandings and urban myths that have been floating around for decades.

 

Larry

[nipper]

Sorry ping is not pre-ignition.

 

ping is simply knock (detonation) that happens at high rpm, when knock occurs at low rpm it changes sound to a heavy rattle, knocking sound. They are both the same thing but occuring under different conditions.

 

"If" you hear pre-ignition which is very rare it causes a low rumbling sound that is hardely detectable, but is very quickly fatal to the engine.

 

 

This is pre-ignition due to a hot spot, not ping.

 

There are actually several different intensities of knock, light, moderate and heavy. Some engines can tolerate light knock(ping) almost indefinately, moderate knock if brief "usually" does little harm. Heavy knock, is very hard on an engine and quickly damages bearings and pistons or blows head gaskets.

 

If you look at a pressure trace of a cylinder that is knocking (pinging) you will see that the cylinder pressure rises smoothly much like it does under normal condtions until just before TDC, then the rate of pressure change increases faster than normal. Shortly after TDC there is a sharp pressure spike which creates a powerful shock to the top of the piston in a time interval of about 1/20000 of a second, as the detonation occurs, followed by a high frequency ringing (which gives light knock its pinging sound). That ringing sound is a characteristic of the bore size of the engine. Large bore engines have a lower pitch compared to a small bore engine.

 

 

 

That is the time interval that "normal" ignition takes place.

 

 

That is incorrect this would be on the intake stroke, as the compression stroke only lasts 180 degrees of crankshaft rotation (actually less since the intake valves close when the piston is already moving up the bore).

 

 

Unfortunately there is a "HUGE" amount of bad info out there on detonation.

Not picking on anyone here, but just trying to correct some misunderstandings and urban myths that have been floating around for decades.

 

Larry

 

probably made worse by trying to explain things

 

ping has been catgaroized as pre ignition and knock. i also should have stuc k with cycle names instead of micxing crank angles. When i talk about ignition or burning of fuel i usually talk in refernce to BTDC not after. Intake strroke starts before the compression storke, hence my 280 degrees comment, so that was correct.

 

For the engineering people

http://powerlab.mech.okayama-u.ac.jp/~esd/comodia2004/C6_1_049.pdf#search=%22combustion%20and%20knock%22

http://www.stanford.edu/~bmoses/knock.html

 

i used to have a great color scan of a flame front, as it looses something in black and white.

 

if your still with me, a great explination of the weakness of the knock sensor

 

http://sine.ni.com/csol/cds/item/vw/p/id/398/nid/124300

 

and more so in english

http://www.exxonmobil.com.sg/files/PA/AP/Synergy_Fuel_System_FAQ.pdf#search=%22combustion%20and%20knock%22

 

scroll down to the second page.

 

nipper

[hotrod]

Interesting links!

 

The first two are good examples of even engineering level research that still uses the Ricardo model of knock proposed in 1919, that the auto-ignition of the fuel air mix occures in the unburned fuel air mix that is being compressed and heated by the advancing flame front.

 

Serious doubt (to my mind proof that this model is faulty) was developed by NACA (predecessor agency to NASA in the early 1940s ).

 

I have yet to see a paper that still supports Ricardos "guess" about the mechanics of knock and in any way refutes very strong physical evidence that it is not correct.

 

In 1943 NACA researchers studied knock with a high speed camera taking pictures at (the then unheard of ) speed of 40,000 frames a second. This was still not fast enough to capture any significant portion of the knock event. But it did allow them to prove that knock always begins in mixture that is actively burning, such as the still burning mixture behind the primary flame front, or in pockets of burning mixture secondary to autoignition, and not in the unburned fuel air mix.

 

Subtle distinction but important regarding control of knock and why anti-knock additives work.

 

http://naca.larc.nasa.gov/reports/1943/naca-report-761/naca-report-761.pdf

 

In 1946 they revisited the photographic study with a 200,000 frame per second camera.

http://naca.larc.nasa.gov/reports/1946/naca-report-857/naca-report-857.pdf

 

http://naca.larc.nasa.gov/reports/1948/naca-report-912/naca-report-912.pdf

 

In any case detonation is a very complex and interesting subject and the fact its cause and mechanics are still debated by Phd's engineers results in many "theories" floating around out there.

 

I personally am very satisfied with the conclusions NACA came up with in 1943-1946 and have yet to see any research paper explain why they might be in error.

 

 

Larry