name that ping
08-19-2003, 11:58 PM
#1
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name that ping
Rennlisters;
here's a question for the theoretically inclined.
On occasion, bearing a load on the engine while at a low RPM, you get that "ping". What exactly is going on? I'm guessing that the sounds generated between the valve stem and lifter, but what sets the sound into motion? what are the actual mechanics that generate that rapid fire,loose change, rattling kind sound?
I only encounter it on my steep driveway, getting the car into motion and have noted it a few times on other occasions, similar conditions, etc.
Appreciate the collective wisdom as usual!
Jeff N.
here's a question for the theoretically inclined.
On occasion, bearing a load on the engine while at a low RPM, you get that "ping". What exactly is going on? I'm guessing that the sounds generated between the valve stem and lifter, but what sets the sound into motion? what are the actual mechanics that generate that rapid fire,loose change, rattling kind sound?
I only encounter it on my steep driveway, getting the car into motion and have noted it a few times on other occasions, similar conditions, etc.
Appreciate the collective wisdom as usual!
Jeff N.
08-20-2003, 06:01 AM
#2
that sound is not a mechanical sound but the sound of small explosions -pinging is premature uncontrolled detonation of the airfuel mixture in the combustion chamber. this can occur if you are using bad gas, spark timing is too advanced, wrong spark plugs (too hot!), or out of tune. since the valves are not completely closed some of the noise escapes and this is what you hear.
of course this has to be caveated by the fact that I am only an armchair expert
of course this has to be caveated by the fact that I am only an armchair expert
08-20-2003, 06:11 AM
#3
RL Technical Advisor
Hi Jeff:
Tough subject,.... Everyone's ears perceive sounds differently and these kinds of things can be challenging to troubleshoot and offer constructive information, via this medium.
Wish I could hear it.
I will tell you that lifters make a tapping sound that increases with RPM. The loudness remains the same.
Pinging, or detonation, makes a metallic rapping sound at low or mid RPMs and application of throttle. The ECU's knock sensors will hear it and immediately crank back the timing to correct this situation. This is caused by a hot engine with too little octane for the moment.
Take a look at http://www.rennsportsystems.com/2.html for more info on detonation that you might find helpful.
Tough subject,....
Everyone's ears perceive sounds differently and these kinds of things can be challenging to troubleshoot and offer constructive information, via this medium.Wish I could hear it.
I will tell you that lifters make a tapping sound that increases with RPM. The loudness remains the same.
Pinging, or detonation, makes a metallic rapping sound at low or mid RPMs and application of throttle. The ECU's knock sensors will hear it and immediately crank back the timing to correct this situation. This is caused by a hot engine with too little octane for the moment.
Take a look at http://www.rennsportsystems.com/2.html for more info on detonation that you might find helpful.
08-21-2003, 12:40 AM
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Loose change sounds like official ping to me, Steve's right, too little octane for that "moment" when you "bog" your engine by adding more fuel in the cylinder. Higher octane means the fuel burns slower and more efficiently, hence no ping. Rev it up, or get yourself a Rennsport chip!
08-21-2003, 01:28 AM
#5
RL Technical Advisor
Jeff:
An addendum,.........
A teensy bit of knock once in a while under low RPM and warm-to-hot conditions is not harmful in itself; remember that the Motronic system is always trying to maintain maximum performance and optimal ignition timing.
Its a matter of degree (pun intended),....
Different gasolines have varying performance and I've had best luck in the Pacific NW with Chevron premium fuels. I would also suggest adding a large bottle of Techron to the fuel if you have not done this and driving a good hard blast to and from White Pass,...
That will really help,.........
An addendum,.........
A teensy bit of knock once in a while under low RPM and warm-to-hot conditions is not harmful in itself; remember that the Motronic system is always trying to maintain maximum performance and optimal ignition timing.
Its a matter of degree (pun intended),....
Different gasolines have varying performance and I've had best luck in the Pacific NW with Chevron premium fuels. I would also suggest adding a large bottle of Techron to the fuel if you have not done this and driving a good hard blast to and from White Pass,...
That will really help,.........