8.1 L PINGING

Maxed-Out · April 9, 2005

I have a friend with an 8.1L engine that pings when hot. We have checked the timing, installed a Hypertech programer and it still has the same problem.

snoman · April 9, 2005

I have a friend with an 8.1L engine that pings when hot. We have checked the timing, installed a Hypertech programer and it still has the same problem.

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The bigger the displacement of the engine with high compression ratio the more likely it will ping in hot weather. The best solution is to raise the octane of the fuel some because if you retard spark enough to prevent ping you will lose performance and MPG. Given that higher grades start at only 3 to 4% more, why not try it and you may find that it runs better overall as well. I use a Hypertech on my 2000 K3500 and I never use straight 87 in it and it never even thinks about pinging either that I has seen in the 5 years I have owned it..

Haulin' 8.1 · April 9, 2005

Ping is fundementally caused by excessive heat in the combustion chamber. There are many likely causes of this. It would be helpful to know mileage and state of tune (what's been done). Are there any other problem areas or any check engine lights etc?

High engine temperature will cause it, the thermostat is supposed to be 195* and that's where it should be near most of the time. What's the engine running at, it should stay below 200 during normal cruise. Over 210 for any length of time is a problem. If it's too hot check the coolant level and dillution. If it's less than 40% water you lose too much heat transfer. Is the fan clutch weak? What's the condition of the fan belt? Check the radiator condition for cleanlyness inside and out. Could the water pump intake hose be sucking closed on the road from radiator restriction or missing it's internal spacer spring? Anything blocking airflow through the radiator such as a winch, lights, plate? A restricted exhaust will make the engine run hot.

Are the spark plugs correct? Are your sure? If the heat range is too hot they will become glow plugs in effect. They will light the charge too soon and overheat the chambers causing ping. Make sure his are correct.

An excessively lean air/fuel ratio (not getting enough gas under power) will burn much hotter than normal and overheat the chambers causeing ping. Also excessive carbon build-up in the chambers raises the compression ratio and hold heat so that it will also act like a glow-plug and cause pre-ignintion and ping. Make sure the fuel system is in order and clean.

Make sure his fuel filter isn't clogged up and restricting flow.

Have a running injector flush done, I use 3M products and they work well. If this isn't obtainable in your area or priced out of reach then you should at least buy a couple of bottles of Chevron Techron fuel additive and run them in consecutive tanks. This stuff is the best bar none. Both will remove carbon also.

Look up my post on the HD forum titled "Did you know our trucks have an AFPR?" and then check the fuel pressure on the truck as I described, in this case shoot for the maximum specification in order to ensure you have enough fuel under load. Chances are the fuel pressure might be too low in this case. If the pressure at WOT drops out of specs with all this done check the fuel lines for damage or kinks and if nothing is found suspect the pump is weak.

Fuel quality is a big factor in detonation (ping) resistance.

Any fuel used should be at least 89 octane for a stock tune and perhaps higher with a timing bump as Snoman pointed out. Using a low grade gas while suffering ping is stupid, make sure it's a good fuel company, yes I know gas is expensive but not as much as an 8.1 rebuild.

Excessive water in the fuel will cause pinging. If your friend has accumulated too much water in his gas tank and or the station he normally buys from has you'll fight a loosing battle trying to stop it. Pick up a bottle of fuel additive that has a high level of Methanol Alcohol in it. These will usually say "Prevents fuel line freeze" on them also. The alcohol will pull all the water out of the tank and make it more combustable. Afterwards ping will be greatly reduced. This trick worked for me recently.

Does the engine burn oil? Oil will lower octane level with fuel leading to ping. If he's burning a lot of oil that would have to be diagnosed and corrected first. Usually valve seals on these engines.

Is his truck an automatic trans? If so make sure the Park/nuetral switch is adjusted and functioning properly. Is the transmission locking the torque convertor clutch too soon? This can cause ping.

Air filter clogged causing the engine to overwork. A defective but working MAF (mass airflow sensor) can really mess up the engine calibration. Swap it with a known good one to check.

Vernon

P.S. Being able to figure problems out like this quickly and accurately is how I make a living. If your mechanic is able to fix your junk right without wasting time an money on unneeded parts don't bitch about the labor bill. LOL

snoman · April 9, 2005

Ping is basically caused by excessive heat in the combustion chamber.

Not really... It is caused by heat, compression ratio and octane of fuel too. If your fuel is not meeting the octane requirement of your engine, it will knock and nothing will really fix it without greatly effecting performance (for the worse) Knock can occur too ways. The most common one is that when the fuel is ingitined by the spark plug it detenates rather than burns and cause the knock and the severity of it depends on the tempature, cylinder pressure and timing along with fuel octane. It can be controlled with engine timing somewhat but not 100% if octane is too low for conditions. The second form is severe and usual happens in engine that are over heating and/or has chamber carbon deposits that ignite mixture even without spark. (this was a bit of a problem with some cars in the 70's) making hard to even shut engine off at times.

Haulin' 8.1 · April 9, 2005

Snoman I don't mean this to sound harsh as I mean you no disrespect. Casual talk can easily sound arguementative or personal on the net. Having said that, when you've learned as much about it as I have you'll agree.

Vernon

Butch 02 Denali · April 9, 2005

I have a friend with an 8.1L engine that pings when hot. We have checked the timing, installed a Hypertech programer and it still has the same problem.

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Maxed, as I just mentioned on another thread,

Some common causes of knocking are:

In order of most common:

Dirty mafs (#1 cause of ping problems if you are using a K&N type oiled air filter)

Bad or sticking EGR valve

Clogged or mismatched injectors.

Clogged fuel filter or bad pump

Clogged cat

Bad 02 sensors

Bad knock sensors

Intake leak

Bad coils/ignition

and many more!!!

Chances are very good it is one of the first 4 on the list!

Of course, obvious problems like if the engine is running lean and/or overheating like the guys said, need to be fixed.

Team ZR-1 · April 19, 2005

I have a friend with an 8.1L engine that pings when hot. We have checked the timing, installed a Hypertech programer and it still has the same problem.

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IMHO the HPP3 does not do a very good tune and is limited on what you can change and by how much

Best bet is to hook up a OBD-II scanner such as the Ease brand and go for a testrun with scanner in record mode.

That recording then can be analyzed to track the problem down and also use that data as how to custom tune the PCM to rid the problem or

I have a water injection kit that can be triggered by vaccum, MAP output voltage, TPS, or MAF frequency output signal.

With that you can lower intake air temps by around 40 degrees.

Myself use in most cases a winter brand of windshield fluid so WI shares same tank as WW does and the fluid has about 30% methanol to water so it really rids knock/ping and allows for higher PE/WOT timing.