[dark.knight]

If it was me I'd show it to the HSS immediately as they would go in detail about the prev owners running history. Sure sometimes they suggest early replacement/unnecessary jobs but that's where the customer has to intervene and ask more questions.

Timing belt change is recommended now due to the age and mileage of the vehicle, the new one will last the remainder of your ownership easily so why risk engine damage. Tell the HSS to give a thorough cleaning of injectors & throttle body, decarbonizing, check spark plugs and V-belt condition. Also use Sys G fuel additive annually and ensure the fuel is of good quality. This should stop/reduce knocking, if it doesn't then only should the engine be looked at.

Knocking is a small symptom of some underlying mechanical fault, so the guy who rubbished it off seems to want to make his buck on overhauling. The PS fluid is also due for change. Simple solution > HSS.

[vinair]

Originally Posted by wooka

Hi!

I've got a 7 year old used Xing.
Have run it in for a year now and have been maintaining it as required. Oil changes at every 5-6K.
One fine day I was pretty low on fuel and drove it around before I got to the filling station. I heard the knocking distinctly that day. Perhaps I was extra alert
It's run 75K total, 15K with me during the last year. Chandigarh traffic and highways.
Fuel top-ups are from one trusted BP pump.

The car has problems with performance ( nothing major, mostly cold start) and there's a mild knocking sound in anything from the second to the fifth gear. It's barely present at coasting speeds.. just clear and distinct ( sounds like water boiling in a covered vessel) when I hit the accelerator . This is present at 10 ~ >100KMPH

Man! I am facing the same issue too with Santro Xing. Its done around 56K until now. Took the car to the Hyundai Service center, the quick diagnosis did not pick anything wrong and everything seemed fine. I am still facing a lot of knocking and total engine shutdown even after the quick check up.

Also, my car returns just 10-11 kmpl!

Mod Note : Please quote ONLY the relevant bits of a post. Quoting a full, long post inconveniences our mobile readers.

Thanks!

[pramodkumar]

Originally Posted by wooka

One fine day I was pretty low on fuel and drove it around before I got to the filling station. I heard the knocking distinctly that day. Perhaps I was extra alert

You have kind of answered your question yourself. A car on low fuel has a fair good chance of sucking in all the dirt and grime from the fuel tank, which is usually settled down.

Get all your injectors cleaned, replace the fuel filter and clean your throttle body. You should be up an running.

A simple bottle of system G should bring in a marked difference. Try that first.

Pramod

[Jeroen]

Glad to see various members offering enthusiastic advise. However, if I were you I would never just start swapping bits or having any work carried out until a competent engineer/mechanic has done some prober diagnostic analysis.

First, and I really can't judge that, is it real engine knocking you hear. Either, you have heard if before and you know what it is, or your mechanic has confirmed. Its often described as pinging sound. When you press on the accelerator it becomes more pronounced. Typically at idle or low loads its not or less present.

Rings a bell??

When you switch off your engine, does it stop immediately or rattles on a bit?

If it is knocking, there are actually several different types of engine knock, but lets keep it simple, check here :

http://en.wikipedia.org/wiki/Engine_knocking

Your car is likely to be equipped with an OBD port, so get it hooked up and see if there are any codes. Has your car a OBD and if so, did they hook it up and saw any codes?

The most simple causes for engine knock are:

- Wrong fuel
If you're using a fuel with a lower octane number then the recommended number you might be encountering engine knock. The solution is very simple, put the proper fuel in!

- Incorrect spark timing
I'm not familiar with your car, again, the easiest is to check this via OBD read out, and if not you just need to check the settings manually. Check spark plugs too.
If it is anything to do with the ignition, its more likely to be the timing than the plugs, but plugs are checked very easily, so you might as well

- Carbon deposits built up in the cylinder
A well equipped workshop should be able to take a little peek in your cylinders to see if there is carbon deposit built up using a simple endoscope.

I don't understand why your mechanic would want to change the time belt or open up the engine head as part of this problem. If it is part of the normal preventive maintenance thats fine, of course. Your owners manual should tell you when it needs changing.

If he suspects the timing belt to be the culprit of the knocking he should be able to clearly measure this. It would have to be pretty loose, or mounted incorrectly to start with in the first place to get the engine to knock. He should be able to measure that easily.

Opening up of the cylinder head, no of course not, find a workshop that invested a couple of hundred bucks in a tool (endoscope) to look into the cylinder! I have one, and I'm just an amateur.

Clean out the throttle body?? Why would you do that or give such advise? First, just look inside the throttle body, and when its is dirty decide on an appropriate course of action.

So, the advice offered by our esteemed members as well as your mechanic seems to be void of any logical and or analytical approach, i.e. just hit and miss. Or perhaps more appropriate call it replace and see what happens.

Admittedly, that might get rid of your problem. I am of a somewhat more cautious disposition and I want to understand what is going wrong first before I start opening up stuff, or replacing it.

Good luck,
Jeroen

[joybhowmik]

Originally Posted by wooka

Hi!
The car has problems with performance ( nothing major, mostly cold start) and there's a mild knocking sound in anything from the second to the fifth gear. It's barely present at coasting speeds.. just clear and distinct ( sounds like water boiling in a covered vessel) when I hit the accelerator .

Before you run away and do some expensive replacements, here's a few quick checks.
Check your air filter - is it too dirty - if so , replace? Are there any obstructions in the inlet manifold?
Is the ignition timing off? Ask your mechanic to check TDC using a strobe.
Is the coolant level okay?

[Jeroen]

Originally Posted by joybhowmik

Before you run away and do some expensive replacements, here's a few quick checks.
Check your air filter - is it too dirty - if so , replace? Are there any obstructions in the inlet manifold?
Is the ignition timing off? Ask your mechanic to check TDC using a strobe.
Is the coolant level okay?

Sounds advices to some quick checks and preferably think things through a bit before you start replacing stuff.

Just to add:

The TDC, Top Dead Center is a given and is fixed. Checking it won't do anything, what I assume you mean is similar to what I suggested, is to check the ignition timing, which is measured against the TDC. Your engine ignition needs a certain advance and that advance is also dependent on RPM and engine loading.

You can do a few basic checks with a strobe. So you check the ignition advance against the TDC.

Better yet, if the car has OBD port, get it plugged into a proper, preferably manufacturer specific OBD analyzer.

Jeroen

[guyfrmblr]

Is the knocking sound heard only at certain RPMs in all the gears? I faced the issue of engine knocking sound at 1200 rpm in all the gears in my i20 crdi. It was more prominent in the 1st and 2nd gear. First the HSS guys just reset the injector codes in ECU but the issue appeared again. Then they cleaned the diesel tank, fuel lines and the injectors after which the issue disappeared.

[RSR]

Where is my post asking wooka to check for DTCs and whether the O2 sensor is causing the problem of hesitation and lurching (by unplugging it)? Where did it go?

It seems to have vanished into thin air after the two threads were merged, possibly due to the large attachment (picture).

Originally Posted by wooka

Now problems as under:

HESITATION: Ever since last winter, the engine has been hesitating during a cold start. It lurches forward as if there's no power delivery and miraculously re-gains consciousness a second later. This is regardless of gear (1st-3rd)
Surprisingly this has continued into the summers.

I would recommend temporarily unplugging the O2 sensor to see if the problem is caused by it. When it's faulty or clogged, it's known to be the cause of engine hesitation & sudden lurching on cars with Hyundai's 1086cc gasoline engine.

[wooka]

Points I need to iterate after going through the posts:

1. I have changed spark plugs and the problem is as before I began troubleshooting.
2. Just used an injector cleaning solution in the tank ( 1 bottle of ABRO injector clean) and have burned twenty litres since then. No difference.
3. I've been using System-G for 3 months now and the lurching at cold start won't improve. I do about 600~1K KMs a month so System G has had plenty of time to work.
4. The timing belt change interval is at 90K I believe. @ 75K I'm not that off. I understand the belt must really be loose for it to cause knocking.
5. The knocking is indeed a pinging sort of sound. Think a diesel engine's noise but more erratic, over the regular petrol engine noise.
6. The mechanic said this is minor but I can clearly make a distinction as the situation deteriorates, and I've made this observation over a few months.
7. If the low fuel caused guck to get sucked up into the system, do I need to get fuel lines and the tank cleaned, fuel filter changed? I thought the fuel filter kept the injectors clean!

Originally Posted by dark.knight

If it was me I'd show it to the HSS immediately as they would go in detail about the prev owners running history
====
Timing belt change is recommended now due to the age and mileage of the vehicle, the new one will last the remainder of your ownership easily so why risk engine damage.
====
Tell the HSS to give a thorough cleaning of injectors & throttle body, decarbonizing, check spark plugs and V-belt condition.
====
Also use Sys G fuel additive annually and ensure the fuel is of good quality. This should stop/reduce knocking
====
The PS fluid is also due for change. Simple solution > HSS.

@Dark knight, decarbonization sounds scary after everything I've read ( and that's a lot). Further do MPFI engines need this at 75K with modern fuel additives etc,, ? System G isn't doing much today.

Originally Posted by vinair

Man! I am facing the same issue too with Santro Xing. Its done around 56K until now.
====
Also, my car returns just 10-11 kmpl!

@vinair, I feel you might need to get your machine ECM mileage readout. If it's a used car the previous owner might have ruined things. Besides this decarb and get your cylinders and gaskets checked.

Originally Posted by pramodkumar

You have kind of answered your question yourself. A car on low fuel has a fair good chance of sucking in all the dirt and grime from the fuel tank, which is usually settled down.
====
Get all your injectors cleaned, replace the fuel filter and clean your throttle body. You should be up an running.
====
A simple bottle of system G should bring in a marked difference. Try that first.

@Pramod, I am jotting this down on my checklist. As mentioned, system G and the injector cleaning solution ( used independently) have yielded little to nothing.

Originally Posted by Jeroen

When you switch off your engine, does it stop immediately or rattles on a bit?
====
If it is knocking, there are actually several different types of engine knock
====
Your car is likely to be equipped with an OBD port, so get it hooked up..
====
- Wrong fuel
If you're using a fuel with a lower octane number
====
I'm not familiar with your car, again, the easiest is to check this via OBD... Check spark plugs too.
If it is anything to do with the ignition, its more likely to be the timing than the plugs....
====
Carbon deposits built up in the cylinder
====
I don't understand why your mechanic would want to change the time belt or open up the engine head as part of this problem.
====
If he suspects the timing belt....have to be pretty loose, or mounted incorrectly to start with in the first place to get the engine to knock.
====
Opening up of the cylinder head, no of course not... look into the cylinder!
====
Clean out the throttle body??

@Jeroen, thanks for your inputs. I'll have the throttle body inspected and cleaned if required.

Originally Posted by joybhowmik

Before you run away and do some expensive replacements, here's a few quick checks.
Check your air filter - is it too dirty - if so , replace? Are there any obstructions in the inlet manifold?
====
Is the ignition timing off? Ask your mechanic to check TDC using a strobe.
Is the coolant level okay?

Air filter is brand new. Purolator. Inlet manifold seemed ok when I opened it ( not sure about the innards but it seemed fine).

Originally Posted by Jeroen

....is to check the ignition timing, which is measured against the TDC. Your engine ignition needs a certain advance and that advance is also dependent on RPM and engine loading.
====
You can do a few basic checks with a strobe. So you check the ignition advance against the TDC.
====
Better yet, if the car has OBD port, get it plugged into a proper, preferably manufacturer specific OBD analyzer.

@Jeroen, There's a real problem with the knocking and it seems to come on only when I accelerate.@ Medium acceleration it is more pronounced.

Originally Posted by guyfrmblr

Is the knocking sound heard only at certain RPMs in all the gears? I faced the issue of engine knocking sound at 1200 rpm in all the gears in my i20 crdi. It was more prominent in the 1st and 2nd gear. First the HSS guys just reset the injector codes in ECU but the issue appeared again. Then they cleaned the diesel tank, fuel lines and the injectors after which the issue disappeared.

@Guy, the fuel lines will be cleaned post inspection

Originally Posted by RSR

Where is my post asking wooka to check for DTCs and whether the O2 sensor is causing the problem of hesitation and lurching (by unplugging it)? Where did it go?
====
It seems to have vanished into thin air after the two threads were merged, possibly due to the large attachment (picture).
====
I would recommend temporarily unplugging the O2 sensor to see if the problem is caused by it. When it's faulty or clogged, it's known to be the cause of engine hesitation & sudden lurching on cars with Hyundai's 1086cc gasoline engine.

@RSR, DTCs? Sorry can't google right now :(
O2 sensor.. is this the one at the exhaust manifold? I do not have any idea where to look, honestly. In case this is out, what are my options?
Sorry you lost your post. Thanks for working another one! Though I wonder how this would affect a cold engine against a warm one. There's no problem in gear, just as I enter one.

There has been some idling engine RMP variation over the past few months. The RPM is up as of today, was lower a few months back prior to the last service.

----------------------------------------------
I'm going to thank everyone for their posts. Very good stuff here and I'll have the HSS guys run their tests against my checklist.

I'm making a little checklist. Please just highlight the point number and approve if need be. I really don't want anyone to have to write the same stuff over and again for one car


Checklist:

1. IgnitionCheck ignition timing @ HSS as no one else seems to know any better here. This is against the TDC I understand
2. InjectorsTest injector spray pattern and volume @ HSS?
3. Fuel linesClean out- fuel lines @ an outside workshop. Change fuel filter? (it's been 14K since the last change)
4. CylindersGet the cylinders opened and see if they need work ( decarb etc.) Will get this done outside @ a workshop.
5. Timing beltTiming belt needs changing anyway. Can't afford a snap.
6. Throttle body cleaning on inspection.OEM Santro belt @ Rs.800 and the rest labor.
7. OctaneI'll add some reagent grade acetone to top the octane and see if it helps. This would be indicative of an unusually high compression ratio and either the mixture of fuel+ air is lean or carbon has reduced available room in the cylinder.I have a bottle lying so that's OK. Have used it for 3-4 months and soon after I discontinued the problems came up. Coincidence?
8. O2 sensorGet the O2 sensor checked and ODB readings for some stats. Will post stats with tBHP as I get them.

Please feel free to contribute.

[RSR]

Originally Posted by wooka

@RSR, DTCs? Sorry can't google right now :(
O2 sensor.. is this the one at the exhaust manifold? I do not have any idea where to look, honestly. In case this is out, what are my options?
Sorry you lost your post. Thanks for working another one! Though I wonder how this would affect a cold engine against a warm one. There's no problem in gear, just as I enter one.

Sorry for the abbreviation, I was clearer in the post that vanished. I meant Diagnostic Trouble Codes or error codes that one gets when the car is hooked up to a code reader/scanner. Does the "check engine lamp" or "malfunction indicator lamp" light up at anytime on the instrument cluster, even briefly?

Yes, the O2 sensor is the one just after the exhaust manifold. This is the one that usually goes bad or gets clogged. In addition to this, your car may have another O2 sensor just after the catalytic converter, depending on the emission norms it was designed for.

There is no need to remove the sensor to test it. It will have a plug, just unplug it and drive the car to see if the hesitation and lurching forward persist. If it doesn't happen, the O2 sensor is the culprit. It would be similar to this:



If it has gone bad, it needs to be replaced. It can cost up to 7k rupees at a Hyundai workshop, but you can source a genuine part outside for cheaper, if you know the part details.

If you're lucky, it may just be clogged. In this case, a careful cleaning will restore it's functionality.

Of course, this is just a possibility that needs to be checked by unplugging it first. It happened on our i10 iRDE which has the same 1086cc engine.

[joybhowmik]

Originally Posted by wooka

Checklist:

1. IgnitionCheck ignition timing @ HSS as no one else seems to know any better here. This is against the TDC I understand
2. InjectorsTest injector spray pattern and volume @ HSS?
3. Fuel linesClean out- fuel lines @ an outside workshop. Change fuel filter? (it's been 14K since the last change)
4. CylindersGet the cylinders opened and see if they need work ( decarb etc.) Will get this done outside @ a workshop.
5. Timing beltTiming belt needs changing anyway. Can't afford a snap.
6. Throttle body cleaning on inspection.OEM Santro belt @ Rs.800 and the rest labor.
7. OctaneI'll add some reagent grade acetone to top the octane and see if it helps. This would be indicative of an unusually high compression ratio and either the mixture of fuel+ air is lean or carbon has reduced available room in the cylinder.I have a bottle lying so that's OK. Have used it for 3-4 months and soon after I discontinued the problems came up. Coincidence?
8. O2 sensorGet the O2 sensor checked and ODB readings for some stats. Will post stats with tBHP as I get them.

Please feel free to contribute.

Originally Posted by wooka

1. Ignition Check ignition timing @ HSS as no one else seems to know any better here. This is against the TDC I understand

This is the critical check.
This is not something that needs a whole lot of specialised equipment (see this

video

)- so you can get it done at a trusted mechanic. At least you will get much better skills working on the car.

Originally Posted by wooka

2. Injectors Test injector spray pattern and volume @ HSS?
3. Fuel lines Clean out- fuel lines @ an outside workshop. Change fuel filter? (it's been 14K since the last change)
6. Throttle body cleaning on inspection.OEM Santro belt @ Rs.800 and the rest labor.

If this is part of preventive maintenance - unrelated to the problem at hand - by all means go ahead.

Originally Posted by wooka

4. CylindersGet the cylinders opened and see if they need work ( decarb etc.) Will get this done outside @ a workshop.

You can get the cylinders inspected for scouring with an endoscope, without detaching the head from the block. Google/search for endoscope of cylinder. For this you need to ask around with engine specialist mechanics. You probably won't get this at HSS - but check with them anyways - if they have one.
Decarbonization is overrated and oversold. However, it's your choice - but do consider this thread before electing for open heart surgery on this account.

Originally Posted by wooka

5. Timing belt Timing belt needs changing anyway. Can't afford a snap.

Here's the guidance from the manual:
Mandatory replacement of camshaft timing belt @ 80 K km or multiples thereof.
Under special conditions (see list below) - replace the timing belt @ 60 K km or multiples thereof.
a) Driving in areas using salt or other corrosive materials or in very cold weather
b) Driving in sandy areas
c) More than 50% driving in heavy city traffic during hot weather above 42ºC
d) Driving in mountainous areas.

I don't know if you have specific evidence of the timing belt having cracks on it, but if not - why change out something that works? But if you still decide to go ahead and do so, ensure to change out the belt tensioner as well.

Originally Posted by wooka

7. Octane I'll add some reagent grade acetone to top the octane and see if it helps. This would be indicative of an unusually high compression ratio and either the mixture of fuel+ air is lean or carbon has reduced available room in the cylinder.I have a bottle lying so that's OK. Have used it for 3-4 months and soon after I discontinued the problems came up. Coincidence?

But by doing this you bypassed the possible cause for knocking in the first place, besides placing undue stress on the moving parts in the engine due to burning non-recommended fuel.

[wooka]

Regarding the O2 sensors,
Was hoping to find something here so I've made a post, though if anyone can tell me what to look for voltage and part wise I'd be thankful. Don't want to be conned! Also any way I can get this adjusted/cleaned?
I noticed increased idle RPMs post service ( in front of me so I don't think any sensors were touched) and a guy said the O2 sensor might need cleaning.

goo.gl/wm4Nvc

Originally Posted by joybhowmik

1. You can get the cylinders inspected for scouring with an endoscope, without detaching the head from the block. Google/search for endoscope of cylinder.

2. Decarbonization is overrated and oversold. However, it's your choice - but do consider this thread before electing for open heart surgery on this account.

3. Here's the guidance from the manual:
Mandatory replacement of camshaft timing belt @ 80 K km or multiples thereof.
Under special conditions (see list below) ...
... if you still decide to go ahead and do so, ensure to change out the belt tensioner as well.

4. But by doing this you bypassed the possible cause for knocking in the first place, besides placing undue stress on the moving parts in the engine due to burning non-recommended fuel.

@joybhowmik,

I'm going point by point here.

1. I'll try to get this done but I'll have a hard time looking for help. Anywhere I can buy the endoscope online?

2. Decarb: I'm going to do this only if the compression ratio has gone up. Can this be scanned through OBD or some alternate method?

3. Any clue how much this should cost @ 3rd party workshops? The belt is for Rs.800 OG Hyundai , and the tensioner, i have no clue, apart from labor.

4. Quantity of acetone used was 1-1.5ml\L of fuel. So thats about .1 to .15 % dilution. I don't think that's a problem as it was used as a fuel additive in Vietnam @ much higher concentrations to increase FE and clean engine parts. However, cheap rubber seals on bikes gave out and resulted in it being discontinued. If anything it's supposed to decrease surface tension, up octane( nothing significant at my usage levels) and clean fuel lines and injectors I believe.

Originally Posted by RSR

1... Does the "check engine lamp" or "malfunction indicator lamp" light up at anytime on the instrument cluster, even briefly?

2. Yes, the O2 sensor is the one just after the exhaust manifold. This is the one that usually goes bad or gets clogged. In addition to this, your car may have another O2 sensor just after the catalytic converter..

3. There is no need to remove the sensor to test it. It will have a plug, just unplug it and drive the car to see if the hesitation and lurching forward persist. If it doesn't happen, the O2 sensor is the culprit.

4. If it has gone bad, it needs to be replaced. It can cost up to 7k rupees at a Hyundai workshop, but you can source a genuine part outside for cheaper, if you know the part details.

5. If you're lucky, it may just be clogged. In this case, a careful cleaning will restore it's functionality.

6. Of course, this is just a possibility that needs to be checked by unplugging it first. It happened on our i10 iRDE which has the same 1086cc engine.

Thanks @RSR,

1. No Diag lights so far. Bulbs are working fine.

2. The one after the cat con will also need to be checked, right?

3. Unplugging will make the O2 sensor read lean? So the mix will get richer and cooler and not knock. This is definitely going to fix it, right? Since I believe the ECM will try to maintain a 50% lean \ rich mixture ratio. I could be wrong, and probably am, please correct me here.

4. 7K this is something I will use a salvaged part for and not pay that much. Am not paid barely enough. Plus I'd rather stomach the mild knocking and cycle to work

5. Clogged would be loaded with carbon? If so, an ultrasonic or chemical bath/ abrasives -- which is the best way out?

6. Thanks for sharing and helping a nuble out.

[joybhowmik]

Originally Posted by wooka

1. I'll try to get this done but I'll have a hard time looking for help. Anywhere I can buy the endoscope online?

Yes at this link or similar and have it shipped to India with a service like this

Originally Posted by wooka

2. Decarb: I'm going to do this only if the compression ratio has gone up. Can this be scanned through OBD or some alternate method?

Check if OBD is throwing up error codes e.g. misfires
Get a compression test, cylinder leak down test and a power balance test done to pinpoint the problem.
See this video of a

compression test

See this video of a

cylinder lead down test.

See this video of a

power balance test

Originally Posted by wooka

3. Any clue how much this should cost @ 3rd party workshops? The belt is for Rs.800 OG Hyundai , and the tensioner, i have no clue, apart from labor.

I got my 2003 Santro's belt and tensioner changed today by my trusted friendly neighbourhood mechanic. My car is at ~ 75K kms.
Cost of Hyundai genuine timing belt: Rs 800/-
Cost of Hyundai genuine tensioner : Rs 550/-
Labour cost : Rs 100/-

Though mind you - I could have waited for another month or so....

Originally Posted by wooka

4. Quantity of acetone used was 1-1.5ml\L of fuel. So thats about .1 to .15 % dilution. I don't think that's a problem as it was used as a fuel additive in Vietnam @ much higher concentrations to increase FE and clean engine parts. However, cheap rubber seals on bikes gave out and resulted in it being discontinued. If anything it's supposed to decrease surface tension, up octane( nothing significant at my usage levels) and clean fuel lines and injectors I believe.

In that case, it's use was not significant.

[wooka]

Thanks joybhowmik,

Will wait till thursday, my trip to the mech, and will post back.

Still, for the O2 sensors, what voltage range am I looking at, and how can they possibly be cleaned?

[joybhowmik]

Originally Posted by wooka

Thanks joybhowmik,

Will wait till thursday, my trip to the mech, and will post back.

Still, for the O2 sensors, what voltage range am I looking at, and how can they possibly be cleaned?

An O2 sensor issue, would show up in the OBD scan. There is a range of O2 sensor codes, so ensure to get the scan done on a dedicated scanner, and have the mechanic refer the service manual for the meaning.