Toyota Ist - Intermittent Ignition Knocking Problem

Tech Mate · September 25, 2014

Hello experts,

I own a Toyota IST (2002) model. This model has 2NZ-FE VVTi engine (1300cc), driven about 85,000 KMs.

Couple of weeks back, it started making an occasional knocking-like noise and I realized this only happens between gear shifts (automatic shift), specially when i drive slow. To be specific, if I drive slow in traffic, when i slightly accelerate and when it is just about to shift from 2nd gear to 3rd, it starts with this rattling noise and after a couple of seconds it goes away. I never get this at idle or even if i rev up the engine and only happens when driven.

I wasn't too sure if the noise was coming out from the timing chain compartment, therefore I took my car to my regular mechanic which he overruled the timing chain after checking, suspected with knocking and advised me to try an EFI tune up which didn't make any difference. Then he suspected the knock sensor and/or the coolant temperature sensor to be failing intermittently, which i replaced them, still no luck. I also replaced the mass airflow sensor. I must say that it never came up with a "check engine" light and multiple scanning reports showed that tuning was right on and didn't indicate anything wrong.

After consulting many repair folks with no luck (which most of them confirmed that it was knocking yet unable find a proper cause), I finally decided to try my last resort - took it to Toyota for a full inspection of the problem. They opened up the hood, inspected the noise, had a test drive. Their diagnosis was that it is caused by a worn piston rings or a valve problem. They also did a compression test and confirmed that cylinder 2 has less compression (around 8:0) which the other 3 cylinders have the expected 10:5 ratio.

I don't consider myself a geek in this field yet I am not a dummy either. I do have some knowledge of how it works and what could cause what. Therefore, though my only lead is to go by Toyota's diagnosis, I would like to seek your expertise and opinions with regard to this before I go for an overhaul of the engine. Could a worn piston ring or values cause an ignition knock or a similar noise? I am truly worried if I would end with bigger issues if I don't fix it right now itself. It would be great to know if I have any other option and I am willing to take my car to any expert in this area.

Greatly appreciate your thoughts...

Note: I do not have any symptoms of oil burn and do not get any blue smoke coming out of exhaust. I also get good gas mileage. Didn't notice a timing miss either...

Thank you!

-Isuru

Rumesh88 · September 25, 2014

During the EFI tune up did they clean the OCV filter/screen? It is a small screen on the oil path to the VVT OCV just by the side and below the OCV valve and sealed off with an Allen key head screw (6mm I guess). Usually with a proper tune up this type symptoms should disappear. However this engine is known for oil sludge formation (due to use of wrong oil type, not changing oil on time etc) on the oil path and clogging of the OCV oil screen. BTW don't listen to agent's BS until you sort out basic things first.

Edited September 25, 2014 by Rumesh88

Fixzit · September 25, 2014

Any chance this could be a faulty knock sensor?

Tech Mate · September 25, 2014

During the EFI tune up did they clean the OCV filter/screen? It is a small screen on the oil path to the VVT OCV just by the side and below the OCV valve and sealed off with an Allen key head screw (6mm I guess). Usually with a proper tune up this type symptoms should disappear. However this engine is known for oil sludge formation (due to use of wrong oil type, not changing oil on time etc) on the oil path and clogging of the OCV oil screen. BTW don't listen to agent's BS until you sort out basic things first.

Thanks a lot for the quick response! No, I don't think an OCV filter was cleaned at any point, though they pulled out the VVTi sensor/ module to check if it was functioning. I will get this cleaned and check again.

Thanks a lot for the pointers!

Tech Mate · September 25, 2014

Any chance this could be a faulty knock sensor?

I replaced the knock sensor and didn't make any difference....

Thanks!

Tech Mate · September 25, 2014

During the EFI tune up did they clean the OCV filter/screen? It is a small screen on the oil path to the VVT OCV just by the side and below the OCV valve and sealed off with an Allen key head screw (6mm I guess). Usually with a proper tune up this type symptoms should disappear. However this engine is known for oil sludge formation (due to use of wrong oil type, not changing oil on time etc) on the oil path and clogging of the OCV oil screen. BTW don't listen to agent's BS until you sort out basic things first.

Quick question, by OCV, are you referring to Camshaft Timing Oil Control Value?

Thanks!

Rumesh88 · September 25, 2014

Quick question, by OCV, are you referring to Camshaft Timing Oil Control Value?
Thanks!

Yes. It is the cylindrical one located just above the alternator mounting bracket with a black 2-wire connector. When the OCV oil screen is removed make sure that the mechanic uses an Allen key of exactly correct size and that it is inserted properly, for otherwise it will spoil the screw head. It is located at an awkward location and need quite a leverage to unscrew. Also you can judge the condition of rest of the oil path once you get to see the amount of sludge on the filter. Sometimes the sludge can be a bit hard to remove. When re-installing make sure the filter is attached to the screw head and inserted, not the filter alone is inserted first into the engine head. BTW do you use Toyota or Mobil for engine oil or is it any other type?

Edited September 25, 2014 by Rumesh88

Tech Mate · September 26, 2014

Yes. It is the cylindrical one located just above the alternator mounting bracket with a black 2-wire connector. When the OCV oil screen is removed make sure that the mechanic uses an Allen key of exactly correct size and that it is inserted properly, for otherwise it will spoil the screw head. It is located at an awkward location and need quite a leverage to unscrew. Also you can judge the condition of rest of the oil path once you get to see the amount of sludge on the filter. Sometimes the sludge can be a bit hard to remove. When re-installing make sure the filter is attached to the screw head and inserted, not the filter alone is inserted first into the engine head. BTW do you use Toyota or Mobil for engine oil or is it any other type?

I got the mechanic to clean it today, the way you mentioned. It was completely covered with sludge and it took some time to clean it. I ran the car for about an hour and the problem still persists... Just by looking at the amount of sludge the filter was covered with, I guess there's possibly a lot more sludge inside the oil path. What options do I have now? Should I try an engine flush or would that be another rip off? My mechanic says maybe we could try pulling out the oil pan and clean whatever that is possible, without trying a complete de-carbonizing.

I bought this car in February this year and I have personally paid a lot of attention to it with on time oil change and stuff. There had been 2 previous owners and I am not too sure how well it was maintained yet it didn't look like it was hacked. Also, I did not have such issues at the time I bought it and there weren't anything strange that I could notice.

The engine oil I have been using is BP Visco 3000. Not sure what type of oil used by previous owners....

Thanks!

Rumesh88 · September 26, 2014

I just do not understand why our mechanics/tune up guys simply overlook this filter which takes only a couple of minutes to remove and clean if you have right tools. Your car may not have been hacked but this engine is very sensitive to the type of oil and the service interval particularly if you/previous owners happened to drive in heavy traffic regularly. Looks like the filter has never been cleaned though it may or may not be the cause of your issue. However I must add here that an overhaul would have addressed all these problems as the agent recommended but it is like recommending a guillotine to clear your dandruff. However since the issue is still marginal let's observe a few more things.

1. Do you know the type of spark plug in use now? Was it changed during the last tune up?

2. Do you use Octane 92 or 95?

3. When the tune up was done did they change or inspect for cracks on the injector seals?

4. Do you get this knock with AC off too? Any noticeable difference with ad without AC?

5. Does your engine sound like a tractor (no offence ha!) when on idle? You can search youtube for tractor noise in VVTi engines to get an idea.

Going for an engine flush I would not recommend for instead you can remove the existing oil and filter. Refill with either T*y*ta or M*b*l 1000 (15W40) (btw both are technically the same) with a new filter. Do a couple of frequent oil/filter changes and see if it improves the situation. If you are running in traffic daily you must reduce the service interval mileage by a few percentage points (after all it is engine hours that matter not the mileage).

If you decide to clean like how your mechanic suggested (but I doubt whether that would yield any results) you must open the cam cover too and see if you have sludge on the cam mechanism (youtube search VVTi oil sludge).

Ruslan · September 26, 2014

Rumesh,

I've changed the OCV filter and ran Engine for 20-30 Min Idle with BG 109 in My Vios after I bought it. it looks much better now (saw slight Varnish gunk when look through oil filler cap before using BG 109). but I guess it will do more harm than good in High mileage engine. now running Castrol Magnatec 15W-40 Semi synthetic, since it's the same price as the Toyota Oil and planing to do 5K oil change intervals even though oil can withstand up to 7K mileage.

Can OP will be benefited using this method, "IF" it's not a high mileage engine?

Edited September 26, 2014 by Ruslan

Tech Mate · September 26, 2014

I just do not understand why our mechanics/tune up guys simply overlook this filter which takes only a couple of minutes to remove and clean if you have right tools. Your car may not have been hacked but this engine is very sensitive to the type of oil and the service interval particularly if you/previous owners happened to drive in heavy traffic regularly. Looks like the filter has never been cleaned though it may or may not be the cause of your issue. However I must add here that an overhaul would have addressed all these problems as the agent recommended but it is like recommending a guillotine to clear your dandruff. However since the issue is still marginal let's observe a few more things.
1. Do you know the type of spark plug in use now? Was it changed during the last tune up?

2. Do you use Octane 92 or 95?

3. When the tune up was done did they change or inspect for cracks on the injector seals?

4. Do you get this knock with AC off too? Any noticeable difference with ad without AC?

5. Does your engine sound like a tractor (no offence ha!) when on idle? You can search youtube for tractor noise in VVTi engines to get an idea.

Going for an engine flush I would not recommend for instead you can remove the existing oil and filter. Refill with either T*y*ta or M*b*l 1000 (15W40) (btw both are technically the same) with a new filter. Do a couple of frequent oil/filter changes and see if it improves the situation. If you are running in traffic daily you must reduce the service interval mileage by a few percentage points (after all it is engine hours that matter not the mileage).

If you decide to clean like how your mechanic suggested (but I doubt whether that would yield any results) you must open the cam cover too and see if you have sludge on the cam mechanism (youtube search VVTi oil sludge).

Yes, I do run in to a lot of traffic, yet I usually do oil changes when I reach around 2500 KM mark and I have never overrun it. But I doubt if previous ownership was attentive to it in such a way...

Here are the answers to your questions:

1. Do you know the type of spark plug in use now? Was it changed during the last tune up? Yes, I got them changed. They are regular Toyota (Denso) plugs (K16-RU11)

2. Do you use Octane 92 or 95? I have been using 95 ever since I bought it, but I know for sure that the previous owner did not. I have also replaced the fuel filter.

3. When the tune up was done did they change or inspect for cracks on the injector seals? They inspected injectors and cleaned them up through some machine. No sure if they inspected particularly for cracks, but I remember them looking at each injector through a magnifier

4. Do you get this knock with AC off too? Any noticeable difference with ad without AC? It happens the same way with or without A/C. No significant difference.

5. Does your engine sound like a tractor (no offence ha!) when on idle? Yes, but slightly. I've read about the tractor noise so I do have an idea of how it sounds. Not sure if this is related or not; when I checked if timing chain was ok, I felt that it was a not tight enough. But the mechanic said it is normal and that the adjuster would automatically tighten it up when running.

By the way, maybe I should change my mechanic as I don't think properly understand a lot things; to be honest, until I mentioned to them about the OCV filter (and I also had to show them where it resides!), they had no clue of such a thing exists! I don't think they know a lot about modern engines yet try and learn things on trial and error. Also I don't find them paying a lot of attention to detail, which I believe is a critical thing for diagnosis. Greatly appreciate if you/ you know of anybody whom you could recommend for me so that I could give it another shot to further narrow this down.

Thanks!

Rumesh88 · September 26, 2014

Rumesh,
I've changed the OCV filter and ran Engine for 20-30 Min Idle with BG 109 in My Vios after I bought it. it looks much better now (saw slight Varnish gunk when look through oil filler cap before using BG 109). but I guess it will do more harm than good in High mileage engine. now running Castrol Magnatec 15W-40 Semi synthetic, since it's the same price as the Toyota Oil and planing to do 5K oil change intervals even though oil can withstand up to 7K mileage.

Can OP will be benefited using this method, "IF" it's not a high mileage engine?

Well it amounts to an engine flush to which I am a bit cautious on a high mileage engine. Then again OP's engine mileage is not that high provided however, it is genuine. Let's see what OP thinks.

Yes, I do run in to a lot of traffic, yet I usually do oil changes when I reach around 2500 KM mark and I have never overrun it. But I doubt if previous ownership was attentive to it in such a way...
Here are the answers to your questions:

1. Do you know the type of spark plug in use now? Was it changed during the last tune up? Yes, I got them changed. They are regular Toyota (Denso) plugs (K16-RU11)

2. Do you use Octane 92 or 95? I have been using 95 ever since I bought it, but I know for sure that the previous owner did not. I have also replaced the fuel filter.

3. When the tune up was done did they change or inspect for cracks on the injector seals? They inspected injectors and cleaned them up through some machine. No sure if they inspected particularly for cracks, but I remember them looking at each injector through a magnifier

4. Do you get this knock with AC off too? Any noticeable difference with ad without AC? It happens the same way with or without A/C. No significant difference.

5. Does your engine sound like a tractor (no offence ha!) when on idle? Yes, but slightly. I've read about the tractor noise so I do have an idea of how it sounds. Not sure if this is related or not; when I checked if timing chain was ok, I felt that it was a not tight enough. But the mechanic said it is normal and that the adjuster would automatically tighten it up when running.

By the way, maybe I should change my mechanic as I don't think properly understand a lot things; to be honest, until I mentioned to them about the OCV filter (and I also had to show them where it resides!), they had no clue of such a thing exists! I don't think they know a lot about modern engines yet try and learn things on trial and error. Also I don't find them paying a lot of attention to detail, which I believe is a critical thing for diagnosis. Greatly appreciate if you/ you know of anybody whom you could recommend for me so that I could give it another shot to further narrow this down.

Thanks!

We you seems to have a quite good understanding in automotive stuff compared to an average user. Why I asked those question was to try and figure out if the issue is due to a problem in sensors leading to wrong output from ECU or if the VVTi OCV is not responding as it should. So far the case points to the latter but I forgot one more very important question - ie whether you get this knock when you drive off just after a cold start and before the temperature comes to middle (within the first 1/2 km from a cold start)?

In No. 3 above I asked if they changed the injector seal which is a hard rubber ring-like thing on each injector.

As for a mechanic I can recommend someone in Moratuwa if it suits you. Send a PM for details. Most probably he will do a tune up and see if the symptoms disappear. I did not want to suggest this since you had already done a tune up.

Edited September 26, 2014 by Rumesh88

Shehan_WCC · September 26, 2014

Hello experts,

I own a Toyota IST (2002) model. This model has 2NZ-FE VVTi engine (1300cc), driven about 85,000 KMs.

Couple of weeks back, it started making an occasional knocking-like noise and I realized this only happens between gear shifts (automatic shift), specially when i drive slow. To be specific, if I drive slow in traffic, when i slightly accelerate and when it is just about to shift from 2nd gear to 3rd, it starts with this rattling noise and after a couple of seconds it goes away. I never get this at idle or even if i rev up the engine and only happens when driven.

Lets break this down ,

If your vehicle runs fine with engine loads but knocks only when shifting gears,i cannot figure out why an under compression engine could cause such irony. If one cylinder is under compression it affects the stoichiometric Air/Fuel ratio but it certainly would not cause an engine knock only when shifting as far as my knowledge persists.

1.Have you eliminated the fact that it could be transmission related ?

2. A knock is usually a jerk but how could it cause a "rattle" noise ?,if its rattling it could be your torque converter

3.If your car is equipped with an Electronic throttle body, a faulty throttle body makes the vehicle run nuts when shifting,in some applications a backfire or popping happens when the TB is faulty because it alters the Air/fuel curve in the ECU.

Technicians don't honestly diagnose a fault properly they just tell you to replace this and that until everything is figured out, a video with the rattling noise would be nice for anything further, as Rumesh88 has pretty much provided you with the best diagnosis procedures possible.

Tech Mate · September 29, 2014

I don't get this issue while the engine is running cold; always happens once it reaches running temp. And yes, they did inspect the rubber seal 'o-ring' in injectors and said they were ok.

I am sorry, I think I wasn't very specific about the exact time this issue happens; this happens just right after a gear is shifted, mostly felt when shifted from 2nd to 3rd, specifically at low RPMs. If I drive with higher throttle, this does not come up. Though nothing changes with A/C off, I have a hunch that this basically happens at a point when the engine feels more load as it is relatively easier to produce this noise on an uphill drive. Also, isn't it that an engine feel more load at lower RPMs?

I did not specifically check for the gearbox yet I got them to inspect and clean the gear oil strainer along with refilling new gear oil. I feel this noise comes out from the driver's side and not from the side or gearbox. Also, I do not get get a gear jerk, at least not to a level I feel it needs attention.

I must also say that it is the mechanics who confirms it is a pinging noise (even the Toyota folks) yet the noise is more or less closer to a rattling noise. I repeatedly asked them if it could also be possible that it is NOT pinging and something else, yet they were firm on their theories. Since now the torque converter in picture, I will get that checked as well.

Thanks!

Rumesh88 · September 29, 2014

Well the ignition pinging is very distinctive and I don't think the mechanics were that incompetent to make a mistake on that. If it happens at low RPM and heavy engine load and it does not happen during cold runs, chances are your ECU is not reading the changing load condition in time to retard ignition timing. Dynamic loading on the engine is calculated with the MAF reading and the RPM reading. When you did your last tune up did they clean the MAF sensor? (Usually they do) If so do you know with what they cleaned it?

Tech Mate · September 29, 2014

Well the ignition pinging is very distinctive and I don't think the mechanics were that incompetent to make a mistake on that. If it happens at low RPM and heavy engine load and it does not happen during cold runs, chances are your ECU is not reading the changing load condition in time to retard ignition timing. Dynamic loading on the engine is calculated with the MAF reading and the RPM reading. When you did your last tune up did they clean the MAF sensor? (Usually they do) If so do you know with what they cleaned it?

Yes, the MAF sensor was cleaned using a contact cleaner which made no difference...

Tech Mate · September 29, 2014

Yes, the MAF sensor was cleaned using a contact cleaner which made no difference...

Also, just a thought, apart from the MAF sensor, shouldn't the knock sensor detect the knock and send a feedback to ECU to retard timing?

MAS · September 29, 2014

Im facing the same issue on my Hyundai. Unable to figure it out as yet. Please update this thread if you manage to fix yours.

Did you check your fuel pressure ?

MAS · September 30, 2014

Also, just a thought, apart from the MAF sensor, shouldn't the knock sensor detect the knock and send a feedback to ECU to retard timing?

You have a point. So maybe its not the engine block but the transmission ?

Rumesh88 · September 30, 2014

Also, just a thought, apart from the MAF sensor, shouldn't the knock sensor detect the knock and send a feedback to ECU to retard timing?

Yes it should. But the issue here is whether the extent of pinging is sufficient to generate a sensor signal large enough for the ECU to identify as a instance of pinging because it is a marginal problem or, on the other hand, the detection threshold in the ECU could be marginally shifted. This is why we are trying to eliminate all other possibilities to find a clue. Although it is highly unlikely better to get the crank position sensor (this one usually is very clean all the time and is very reliable) cleaned as well.

Tech Mate · October 1, 2014

Yes it should. But the issue here is whether the extent of pinging is sufficient to generate a sensor signal large enough for the ECU to identify as a instance of pinging because it is a marginal problem or, on the other hand, the detection threshold in the ECU could be marginally shifted. This is why we are trying to eliminate all other possibilities to find a clue. Although it is highly unlikely better to get the crank position sensor (this one usually is very clean all the time and is very reliable) cleaned as well.

Ok. So I got them to check and clean the crank position sensor today. It seemed that it was in a very good state yet it didn't help resolving the issue. I also asked them to check for any issues with torque converter and I will update once I get it done.

One unrelated question - just out of curiosity, is it possible that I use full/ semi synthetic oil for this engine, given the mileage being around 85,000KM? Are there long term benefits/ issues of using it? If so, which is the best - fully/ semi-synthetic?

The Don · October 1, 2014

Ok. So I got them to check and clean the crank position sensor today. It seemed that it was in a very good state yet it didn't help resolving the issue. I also asked them to check for any issues with torque converter and I will update once I get it done.
One unrelated question - just out of curiosity, is it possible that I use full/ semi synthetic oil for this engine, given the mileage being around 85,000KM? Are there long term benefits/ issues of using it? If so, which is the best - fully/ semi-synthetic?

whether you use full or semi synthetic engine oil is dependent on how frequently you use the car and the type of car.

If you use the car infrequently, and car is a normal car its best to stick to either mineral oil or semi synthetic and change engine oil at least 6 months. This is because of chemical break down of oil over time, you can't really take advantage of the longer service intervals. The detergants also have a bad habit of dislodging sludge which then block oil lines, a common issue with infrequently used cars.

If you use the car frequently then there is a benefit of sorts as it provides benefit as the detergents will keep it cleaner and you'll get slightly longer service intervals. But its recommended you change oil every 10K kms at least or every year. If you use semi synthetic you will have to change every 5000kms.

But the real benefit is in high performance engines with high compression, or which live in the higher end of the rpm range, and are revved hard. Synthetic oils have better flow charactersistics in all temperatures and will offer better protection and leave less deposits.

Edited October 1, 2014 by The Don

Rumesh88 · October 1, 2014

Ok. So I got them to check and clean the crank position sensor today. It seemed that it was in a very good state yet it didn't help resolving the issue. I also asked them to check for any issues with torque converter and I will update once I get it done.

Of course as I said the crank position sensor remain clean most of the time but it was just that I wanted to see every simple thing possible done. To the proverbial guillotine then......

MAS · October 2, 2014

I am using Shell Ultra fully synthetic for almost 7 years now. I change oil between 7,500 and 10,000. Its a daily runner. No issues. My mechanic advised me to change the oil filter twice for every oil change. Example: 1st filter during oil change. 2nd filter around 4,000 to 5,000 (no oil change). The cycle repeats.

Tech Mate: On the knocking issue, please keep us updated on your progress. Many thanks !

JadeyBlitzen · October 4, 2014

The low compression on one piston and this tractor noise you mentioned makes me wonder if the valves aren't seating properly as opposed worn piston rings.

Also could you explain this knocking noise better? does it happen on all rpms or above a certain rpm/load? Try letting the car shift at different points in the rev range and see if there's a specific point where the knocking picks up and peaks. I'm guessing when you say it doesn't happen when the engines cold you are talking about when the blue temperature light is on. Anyway the more I analyse this issue the more I keep coming back to a faulty vvti system.