engine knock Toyota corolla 141 (3ZZ-FE) Engine Knock

[baksp]

Please suggest ways to isolate and identify engine knock sound. thanks

[kush]

Engine knock sound or slow ideal / engine vibration

Former is a common problem with the car and easily rectified by cleaning/ replacing air filter and the air flow sensor  

[baksp]

thanks for the reply. so far work done is as follows.

# engine top over haul (big end bearing replaced)

# fuel filter clean

# fuel lines clean

# air inlet and exhaust manifold clean

# air filter clean

# plugs replaced

# compression checked

 

any thing else to do?

[Twin Turbo]

Wild guess A possible piston slap? 

Edited October 8, 2016 by Twin Turbo

[kush]

What is the mileage, did you do a diagnostic before doing all this stuff

[Rumesh88]

What do you mean by "knocking sound". Is it the noise you get when the ignition is too advanced (pinging, spark knock or pre-ignition )? Or is it the engine vibration you  get as in slow idle?

[baksp]

On 10/10/2016 at 9:35 AM, Rumesh88 said:

What do you mean by "knocking sound". Is it the noise you get when the ignition is too advanced (pinging, spark knock or pre-ignition )? Or is it the engine vibration you  get as in slow idle?

looks like spark knock. at 1600-2100 RPM and when engine loaded. takes few minutes of running to make the sound.does not give a sound when engine is totally cold.

[baksp]

On 10/10/2016 at 7:42 AM, kush said:

What is the mileage, did you do a diagnostic before doing all this stuff

Over consumption of Lub Oil  was observed.

[baksp]

the compression reading was 12. (satisfactory)

[Rumesh88]

37 minutes ago, baksp said:

looks like spark knock. at 1600-2100 RPM and when engine loaded. takes few minutes of running to make the sound.does not give a sound when engine is totally cold.

Then it will be very difficult to isolate the issue. Go for a general tune up (in fact it is a clean up) including clean up of the throttle body, PCV valve, OCV filter, check/replace fuel injector seals, clean up of injectors and check/replace fuel filter etc. If you really want to try and isolate begin with checking the injector seals. They may have developed tiny cracks and hence may allow some unmetered air into the manifold. Since  you have mentioned an abnormal oil consumption check the PCV valve as well.

However these are easy things that you have to do anyway whether there is an issue or not. If it does not solve the problem you may have to go for more serious things like check/replace timing chain, check replace valve guides etc.

Edited October 13, 2016 by Rumesh88

[baksp]

Hi, done all other than

# injector seals

# PCV valve

 

shall do. thanks

[MAS]

Try the least costly options first. I had a similar problem when the engine was on load. No ECU error codes.  Checked fuel volume - it was normal. Then on AL, it was mentioned to try by cleaning the MAF sensor.  It worked for me.  

Edited October 14, 2016 by MAS

[baksp]

On 10/8/2016 at 4:19 PM, Twin Turbo said:

Wild guess A possible piston slap? 

Not confirmed yet by technician. thanks

[baksp]

3 hours ago, MAS said:

Try the least costly options first. I had a similar problem when the engine was on load. No ECU error codes.  Checked fuel flow - it was normal. Then on AL, it was mentioned to try by cleaning the MAF sensor.  It worked for me.  

Shall attempt. Thanks for support

[baksp]

7 hours ago, Rumesh88 said:

Then it will be very difficult to isolate the issue. Go for a general tune up (in fact it is a clean up) including clean up of the throttle body, PCV valve, OCV filter, check/replace fuel injector seals, clean up of injectors and check/replace fuel filter etc. If you really want to try and isolate begin with checking the injector seals. They may have developed tiny cracks and hence may allow some unmetered air into the manifold. Since  you have mentioned an abnormal oil consumption check the PCV valve as well.

However these are easy things that you have to do anyway whether there is an issue or not. If it does not solve the problem you may have to go for more serious things like check/replace timing chain, check replace valve guides etc.

Removed the thermostat and coolant temperature sensor and ran the car idling and loading. Surprisingly NO KNOCK, Am puzzled on the latest finding. any clues?

[Dushyantha]

did you test the temperature sensor and the thermostat to see if they are working correctly ?

[baksp]

2 hours ago, Dushyantha said:

did you test the temperature sensor and the thermostat to see if they are working correctly ?

Yes I did. Temperature checked by Handheld pyrometer. 

Readings were taken in ohm meter '00 and shown in chart.

Thermostat checked and found opening at 85C

 

 

[Rumesh88]

10 hours ago, baksp said:

Removed the thermostat and coolant temperature sensor and ran the car idling and loading. Surprisingly NO KNOCK, Am puzzled on the latest finding. any clues?

ECU adjusts the ignition timing to an optimum level according to engine load, RPM and coolant temperature. Removing the thermostat will result in engine taking a longer time to reach its working temperature (in this case it is 95 C I believe) and is not good for the engine on the long run. If you just disconnected the coolant temp sensor you should have got a CEL indication and the ECU would then set the ignition timing to a predetermined (safe mode) value ignoring the engine temperature. The only clue you get is that your ECU is doing its job. However just to confirm get the coolant temp value read by scanning with the engine fully warmed up. It should read something close to 95 C.

BTW there are two other things that can cause pre-ignition. ie wrong octane fuel and wrong spark plug temperature rating (using a hotter plug). Check and confirm if the plug temperature rating and fuel octane is right for your car.

 

[baksp]

6 minutes ago, Rumesh88 said:

ECU adjusts the ignition timing to an optimum level according to engine load, RPM and coolant temperature. Removing the thermostat will result in engine taking a longer time to reach its working temperature (in this case it is 95 C I believe) and is not good for the engine on the long run. If you just disconnected the coolant temp sensor you should have got a CEL indication and the ECU would then set the ignition timing to a predetermined (safe mode) value ignoring the engine temperature. The only clue you get is that your ECU is doing its job. However just to confirm get the coolant temp value read by scanning with the engine fully warmed up. It should read something close to 95 C.

BTW there are two other things that can cause pre-ignition. ie wrong octane fuel and wrong spark plug temperature rating (using a hotter plug). Check and confirm if the plug temperature rating and fuel octane is right for your car.

 

Thanks for all help. Yes i got "Check Engine System". Also thermostat and sensor was checked and readings are given in top graph. This car is used to Octane 92. We used Octane 95 for test purpose but knock persisted.  Spark plugs were replaced from TOYOTA LANKA inventory and was same as before.

[Rumesh88]

5 minutes ago, baksp said:

Thanks for all help. Yes i got "Check Engine System". Also thermostat and sensor was checked and readings are given in top graph. This car is used to Octane 92. We used Octane 95 for test purpose but knock persisted.  Spark plugs were replaced from TOYOTA LANKA inventory and was same as before.

You seem to have done most of the homework :D. Although the above graph shows  the normal behavior of a ECT sensor still you need to confirm if the ECU reads the temperature correctly. Since you have a pyrometer in hand compare its reading with that of the ECU. If the ECU reads a lower value than the actual then it can result in advanced ignition timing for a given engine temperature. 

[baksp]

12 minutes ago, Rumesh88 said:

You seem to have done most of the homework :D. Although the above graph shows  the normal behavior of a ECT sensor still you need to confirm if the ECU reads the temperature correctly. Since you have a pyrometer in hand compare its reading with that of the ECU. If the ECU reads a lower value than the actual then it can result in advanced ignition timing for a given engine temperature. 

shall attempt.

All suggestions are welcome.

thanks for all help.

[baksp]

hi, all measures indicated were tried but sound persist at a different RPM (1900-2400). Any more tips? thanks

[Dushyantha]

since you have tried most of the basic things that can be checked you could take it to TL and let them diagnose the fault .  of course you would have to pay an amount for their diagnostics . but then if the problem can be found without removing and replacing things blindly its better easier and less time consuming to pay and find the exact problem . 

btw does this engine come with a knock sensor ?

Edited October 15, 2016 by Dushyantha

[baksp]

On 10/15/2016 at 9:07 PM, Dushyantha said:

since you have tried most of the basic things that can be checked you could take it to TL and let them diagnose the fault .  of course you would have to pay an amount for their diagnostics . but then if the problem can be found without removing and replacing things blindly its better easier and less time consuming to pay and find the exact problem . 

btw does this engine come with a knock sensor ?

The engine comes with a knock sensor and it is told that "Check Engine System" alarm should flash in the event of a faulty knock sensor, it certainly does when sensor wires are removed. There is no change of behavior when sensor is fitted/ wire removed.

 

still studying as the sound is annoying. 

[Rumesh88]

31 minutes ago, baksp said:

The engine comes with a knock sensor and it is told that "Check Engine System" alarm should flash in the event of a faulty knock sensor, it certainly does when sensor wires are removed. There is no change of behavior when sensor is fitted/ wire removed.

 

still studying as the sound is annoying. 

Not necessarily so! Knock sensor is  a piezo-electric microphone which generates an electrical signal according to the engine noise. Although it is a reliable device usually if it has lost  its sensitivity it may fail to detect the knock.