Toyota Vios 2003 - “Ignition Knock”

[Buddhikaiw]

Mine is a Vios [Toyota] 2003. I’ve been experiencing an “ignition knock” for last 1 ½ years. As a result of this my petrol efficiency is not good [it is between 8-10 km/L in Colombo]. I’ve checked this with one of the mechanics who is a motor engineer himself. He initially said that, he needs to inspect certain things. Accordingly he checked engine plugs and some other things usually considered in tuning-up an engine. They are perfectly all right. After several testing he decided the caused may be with the computer box of the car assuming that there may be a timing problem, where the petrol is not supplied to the ending at the correct time when it is needed. [Luckily he is a honest guy and didn’t charge since the job was not completed yet]

What do you think about my issue? Will this be sorted-out once the computer box [it cost me around 20K] is replaced? Is this a common issue in vios ? What could be the possible causes? Experienced guys…………..please help me in this regard.

[MAS]

What is the mileage? Was the timing belt replaced?

[k9master]

Hi Buddhika,

Ignition knock is generally caused by bad ignition timing most commonly by a misaligned distributor. But in your case I think the Toyota NZ engine has direct ignition, where the ignition timing is controlled electronically by the ECU (the computer box) so its natural for anyone to assume its caused by same.

But a knock can also be generated by carbon deposits in the combustion chamber, which tend to carry the heat from the previous ignition and then ignite the fuel air mixture before the plug creates the spark at the correct time.

Why don't you go to a place which has the required tools to diagnose the ECU which will monitor and report on ignition timing as well. After this you can see if the problem is with the ECU or not?

Over to the experts...

[NPP]

8-10. ? seems normal to me

[k9master]

8-10. ? seems normal to me

He has not mentioned whether its an auto or manual. 8-10kml is pretty normal in colombo traffic, for a Vios with an Automatic Tranny, IMO

Since the OP has been tolerating the knock for 1 1/2 years its safe to assume that this doesnt happen in low RPMs which will be a much severe case. It must be occuring at above 2.5k or so when the engine is trying to rev up and deliver the power to cope up with the load of accelerating. AFAIK this will not affect fuel consumption much in city driving but you'll definitely see an impact in power.

[Buddhikaiw]

Thanks friends,

This is a auto one with NZE engine.

knock is generating normaly at gerar shifting from 2nd gear to last. Sometimes vehicle stops with the ignition knock when accelarating hard. This happened few times in colour lights when I tried to accelearaste hard. In such time start is difficult.

My mechanic has cleaned the combustion chamber using a chemical [in a sealed bottled]. He connected this bottle withe the fule sytem and kept start the vehicle around 15 mins. But there was no major change in knock.

As per your comments 2 causes can be either carbon deposits in combustion chamber or timming issue in computer box???????????

I would be greatful if you can suggest a place where i can check my computer box other than the agents.

Special thank to K9master for ur valued input.

Thanks all

[The Stig]

Mine is a Vios [Toyota] 2003. I’ve been experiencing an “ignition knock” for last 1 ½ years. As a result of this my petrol efficiency is not good [it is between 8-10 km/L in Colombo]. I’ve checked this with one of the mechanics who is a motor engineer himself. He initially said that, he needs to inspect certain things. Accordingly he checked engine plugs and some other things usually considered in tuning-up an engine. They are perfectly all right. After several testing he decided the caused may be with the computer box of the car assuming that there may be a timing problem, where the petrol is not supplied to the ending at the correct time when it is needed. [Luckily he is a honest guy and didn’t charge since the job was not completed yet]

What do you think about my issue? Will this be sorted-out once the computer box [it cost me around 20K] is replaced? Is this a common issue in vios ? What could be the possible causes? Experienced guys…………..please help me in this regard.

The computer box you are referring to is called an E.C.U and yes it might be the cause among many other things.

As for the part about replacing it first you should try to see if you can reflash the current ECU with a new ecu map, any electronic tuning place will be able to change certain parameters and test. I would suggest going the agents or any other reputed place.

[varunatech]

Mine is a Vios [Toyota] 2003. I’ve been experiencing an “ignition knock” for last 1 ½ years. As a result of this my petrol efficiency is not good [it is between 8-10 km/L in Colombo]. I’ve checked this with one of the mechanics who is a motor engineer himself. He initially said that, he needs to inspect certain things. Accordingly he checked engine plugs and some other things usually considered in tuning-up an engine. They are perfectly all right. After several testing he decided the caused may be with the computer box of the car assuming that there may be a timing problem, where the petrol is not supplied to the ending at the correct time when it is needed. [Luckily he is a honest guy and didn’t charge since the job was not completed yet]

What do you think about my issue? Will this be sorted-out once the computer box [it cost me around 20K] is replaced? Is this a common issue in vios ? What could be the possible causes? Experienced guys…………..please help me in this regard.

Please specify the patterns first. What RPM levels the knock arises, and the type of fuel you use (Octane value).

Can be many reasons,

1. Knock sensor issues.

2. Timing issues and this has relationship to many things.

3. Preignition knock due to combustion chamber carbon deposits.

First thing, if you need help in a forum, please mention how it behaves. Exact behavior of the issue as much as possible in simple sentences.

I had resolved few ignition issues of friends. Will try to help based on what I have learnt.

[varunatech]

Please specify the patterns first. What RPM levels the knock arises, and the type of fuel you use (Octane value).

Can be many reasons,

1. Knock sensor issues.

2. Timing issues and this has relationship to many things.

3. Preignition knock due to combustion chamber carbon deposits.

First thing, if you need help in a forum, please mention how it behaves. Exact behavior of the issue as much as possible in simple sentences.

I had resolved few ignition issues of friends. Will try to help based on what I have learnt.

By the way, if you drive without always thrashing the gas peddle......you get over 11kmp/l in colombo city. For this I have solid data, after multiple tests. If anyone interested I can post the test conditions.

[terrabytetango]

Nevermind.

Edited January 2, 2012 by terrabytetango

[Buddhikaiw]

Hi All,

Knock occurs in following circumstances;

[1] it starts just after the gear shifting [mine is auto]. It continued for 2,3 seconds and vanishes. Then again stars after the next gear shifting and continued in a similar pattern after each and every shifting.

[2] At higher RPMs [say above 2500] knock may continued specially when i kick-down to get more power.

[3] when I break and hold the car at "D" position

[4] when I stop moving the car and then accelerated hard to get more power [Eg - when stops at the colour lights and accelerated exceptionally hard when green is on] car might get stopped with the knock. Then the start is difficult. Have to try it for 3, 4 times to start.

[5] when i start in the morning the knock is not there. it starts after around 5 minuets, once the engine is heated

for your specialist advise please

Thanks.............

[varunatech]

Hi All,

Knock occurs in following circumstances;

[1] it starts just after the gear shifting [mine is auto]. It continued for 2,3 seconds and vanishes. Then again stars after the next gear shifting and continued in a similar pattern after each and every shifting.

[2] At higher RPMs [say above 2500] knock may continued specially when i kick-down to get more power.

[3] when I break and hold the car at "D" position

[4] when I stop moving the car and then accelerated hard to get more power [Eg - when stops at the colour lights and accelerated exceptionally hard when green is on] car might get stopped with the knock. Then the start is difficult. Have to try it for 3, 4 times to start.

[5] when i start in the morning the knock is not there. it starts after around 5 minuets, once the engine is heated

for your specialist advise please

Thanks.............

My friend, first you need to do a proper diagnosis from an expert. I have a feeling your friend engineer might be correct as the car stops and chokes when you hard accelerate. A engine scanner, a fuel pressure meter and lot of experience will help here.

It does not sound like a simple case of carbon deposits or looks pretty straight forward.

Taking to the agents or to an engineering company (not a replace this replace that company) will help.

By the way ECUs are available with agents as well as in Delkanda.

[jayashantha12345]

What is actually a "PRE IGNITION NOISE "... i dont know this and.. I cant understand this word.pls help

[The Stig]

What is actually a "PRE IGNITION NOISE "... i dont know this and.. I cant understand this word.pls help

Its what we commonly refer to as "knocking", thats when the fuel inside the cylinders ignite before the end of the compression stroke comes to an end and fires the spark plugs.

This is what it sounds like

Hear that "taka taka take" noise ? thats whats called pre ignition noise