Pinging sound: 1996 Toyota Corolla (1.6 L) Auto Trans.

[quote:eaf8c24af4="Timothy1027"]This car has high mileage (181,778) but has been well cared for. It runs great, plenty of power and compression, no codes, starts & runs fine except for the following:

1. Poor gas mileage.
2. Slight pinging (only at 1/8 throttle opening).
3. Spark plug insulators on new plugs are (bleached) WHITE.

The engine is NOT overheating. I did a complete tune up, checked the EGR and it is working fine, replaced all the vacuum lines, and checked the ignition timing. All good. Still pings. I'm stumped. :-([/quote:eaf8c24af4]


Other causes of detonation include excessive compression, elevated engine operating temperature, preignition, overadvanced ignition timing (spark knock), lean fuel mixture, spark plugs that have too hot a heat range for the application, low octane fuel,

[quote:fd6e16af2b="rasmataz"][quote:fd6e16af2b="Timothy1027"]This car has high mileage (181,778) but has been well cared for. It runs great, plenty of power and compression, no codes, starts & runs fine except for the following:

1. Poor gas mileage.
2. Slight pinging (only at 1/8 throttle opening).
3. Spark plug insulators on new plugs are (bleached) WHITE.

The engine is NOT overheating. I did a complete tune up, checked the EGR and it is working fine, replaced all the vacuum lines, and checked the ignition timing. All good. Still pings. I'm stumped. :-([/quote:fd6e16af2b]

Other causes of detonation include excessive compression, elevated engine operating temperature, preignition, overadvanced ignition timing (spark knock), lean fuel mixture, spark plugs that have too hot a heat range for the application, low octane fuel,[/quote:fd6e16af2b]
The compression range is (215 to 226 psi) on all 4 clylinders (within Toyota specs), the engine operates at normal temps, the ignition timing is 10 degreess BTDC (as/Toyota specs), the spark plugs are correct NGK (OEM specified), I use regular fuel (correct / Owner's Manual).

Since the EGR checks out-if it has a knock sensor check it-the computer might not be seeing it and not retarding the timing as required


FYI
My Mitchell book says about compression:

Compression: 191psi
Minimum Comp. 142psi
Max. Variation between cylinders 14psi

[quote:510d3bf8f6="rasmataz"]Since the EGR checks out-if it has a knock sensor check it-the computer might not be seeing it and not retarding the timing as required


FYI
My Mitchell book says about compression:

Compression: 191psi
Minimum Comp. 142psi
Max. Variation between cylinders 14psi[/quote:510d3bf8f6]
-----------
The engine does not have a knock sensor.
The factory service manual says about compression: "STD...191 psi) or more."
I checked the valve timiing - Dead Nuts.
I replaced the fuel filter (in case of clog).
Still slight ping. I am STILL stumped.

[quote:4cc998b551="Timothy1027"][quote:4cc998b551="rasmataz"]Since the EGR checks out-if it has a knock sensor check it-the computer might not be seeing it and not retarding the timing as required


FYI
My Mitchell book says about compression:

Compression: 191psi
Minimum Comp. 142psi
Max. Variation between cylinders 14psi[/quote:4cc998b551]
-----------
The engine does not have a knock sensor.
The factory service manual says about compression: "STD...191 psi) or more."
I checked the valve timiing - Dead Nuts.
I replaced the fuel filter (in case of clog).
Still slight ping. I am STILL stumped.[/quote:4cc998b551]

Could be lean mixture-lets try going into the mind of the Computer by checking its parameters on the injector pulses,Coolant Temperature/Oxygen sensors with a Scan Tool.

When you check the ignition timing did you jump the diagnostic connector?