[yasw_anth]

HE owns a Santro 2001 covered approx 45k kms, he had been using it for the last 7 yrs. Last few yrs had noticed that the engine oil level reduces much prior to the service due date. Reduces by abt half a litre for every 1000km run . The mechanic @ Kun Hyundai says that one cylinder is weak showing low compression. Mech says it will cost about Rs25k and needs to open the engine..He gets an avgerage FE of 15kmpl without Ac and abt 9-10 with Ac...
Guys plz help .. what might be the problem ?

[yasw_anth]

guys the situation has worsened now, the people at Kun Hyundai service centre(ambattur) suggested to get the work done immediately else it might cause lots of damage to the engine.
Noticed today: when we raise the Rpm in idle there is some black smoke from the exhaust and carbon deposits expelling out also there is a humming noice for which they said there is a problem in the a/c compressor !!
Guys please help us ...

[nura]

I am reviving an old thread as I seem to have a similar problem on my 7-year old Santro Zip Plus LS.
I had been noticing an intermittent, barely-noticeable misfiring problem in the car. I am not even sure if misfiring is the correct word. When trying to accelerate, for a fraction of a second, I used to feel as if the car had stopped accelerating but the problem used to occur even while I was just cruising. This problem occurred with AC on as well as off. Another problem that I noticed was that when the car was idling & AC was on, there was a periodic thumping noise coming from the engine, almost as if a subwoofer was playing softly under the bonnet. This noise would immediately disappear if I switched off the AC.
I gave the car for a full service to a Hyundai dealer's workshop. They changed the spark plugs, engine oil, air filter & petrol filter, cleaned the fuel pump, did some gear oil treatment & also decarbonized the engine. The misfiring (if it was that) while accelerating & cruising disappeared but the subwoofer-like thumping noise remained.
After a couple of weeks, I opened the bonnet one day, when the engine was on & found a spark emanating from the proximal end (not the end which is fixed to the the spark plug but the other end) of HT cord number 3. I took the car to another Hyundai dealer's workshop & they found that the insulator on the spark plug in cylinder number 3 had broken into 2 pieces. They changed the spark plug (they put in a used one) & when they re-connected the HT cable, the sparking problem disappeared. I took the car & as soon as I started driving it, I realised that the original misfiring had restarted. The subwoofer-like noise of course was also there.
I plan to get the old spark plug replaced with a new one tomorrow but my questions are
1. Why did the insulator on a new spark plug break?
2. Why was there no misfiring when I was driving around with the broken plug but misfiring restarted when the plug was replaced (albeit with a used plug)?
3. Do these events suggest a problem with the HT cord, ignition coil or engine cylinder number 3?
4. What is causing the muffled subwoofer-like thumping noise when the AC is switched on & the engine is idling?

[jassi]

wow i never knew this was happening to other people - i have had the same problem in my santro (xing erlx 2006 model not the ls as mostly reported here). My symptoms match the original posts on pages 1-2 and not the ones on this page!
In gear 2 and sometimes 3, the acceleration will go away and car will start de-accelarating , then i drop a gear and it gets better. Sometimes i have to go all the way down to 1st gear till i can start accelerating again. Pedal to the metal makes no difference, there is absolutely no power going to the wheels. This has been there since 6 months of purchase and while i have undergone a K&N CAI and even a header job the problems still remain. Hyundai engineers blame it on my cai and/or headers, but the problem was there before that. And in almost 5 yrs my car has only done 27k kms. The problem happens once or twice a month now as compared to once a week earlier (before various mods).
If anyone has fixed it please post here. In my case since its not so frequent I haven't pursued it very diligently, but wouldn't mind going for some performance spark plugs, cables etc

[SPIKE ARRESTOR]

@Nura the insulator on a new spark plug can only break because of overtightening, or if there is a quality issue with the plug.

[Otto]

Since there are many posts here, here's some stuff that can help

1. a car's engine will not lose compression in the first 200,000kms atleast for a well maintained car.
2. De-carbonising the head is not required before that due to the quality of the fuel (cleaner burning) in use. BUT, if you've tried everything else, it might be the only solution.
Also strange is how you could have the injectors cleaned with such a young engine life.
3. Most of the problems lie with the fuel ignition and air intake. Since you have already tackled these two, I suggest you now go with the trouble shooting technique of elimination, since you car loses power in the slogging gears of the transmission.

When was the last time you had the timing belt changed?
Since the car is an Mpfi engine, I also suggest that you check the accelerator to engine signal cable (cars with DBW - Drive by wire) - I'm not sure if your santro is DBW.
Have the fuel tank cleaned and put in an additive for cleaning out the injectors.
I'm assuming you've replaced the fuel filters. If you haven't, try that first.

With respect to the other thread on the noise with the A/C - it could be your overpressure/solenoid valve malfunctioning - the valve is open when the A/C is off and closed when you switch the A/C on. If this valve is leaking, it could make that noise. your A/C drive belts and pulley may be failing. Replace them, if they haven't been replaced before and ooh! do you by any chance have an issue with cooling after a while? like say - the a/c is good initially, but later on you feel a loss in cooling?
time to get your condenser and evaporators flushed and cleaned. there could be an oil deposit in them.

[nura]

Thanks @SPIKE ARRESTOR & @Otto.
The drive belts were replaced not too long ago & the pulleys are also fine. Loss of AC cooling had occurred 7-8 months ago. Cured after condenser was cleaned. No problem with cooling now.
Where is this over-pressure solenoid valve situated & how does one check it out?
The injectors were cleaned today & the hesitation during acceleration has gone but the sparking is still there. The thumping noise (rough idle with AC on) was also less after the injector cleaning but is the same as before now.
Showed the car to another technician an hour ago. He interchanged number 3 HT cable with another (not sure which number). The sparking remains at the same spot. So it seems the cables are fine. Does this mean the ignition coil is to fault? Why should there be a spark at the coil end of the HT cable? I would have thought a faulty coil would not send any current out to the cable?
Going for another check-up tomorrow to the workshop.
Btw, do authorized service centers of automobile companies have the equipment to check injector flow rate & spray pattern or are there specialized workshops for this kind of work?

[Otto]

Originally Posted by nura

Thanks @SPIKE ARRESTOR & @Otto.
The drive belts were replaced not too long ago & the pulleys are also fine. Loss of AC cooling had occurred 7-8 months ago. Cured after condenser was cleaned. No problem with cooling now.
Where is this over-pressure solenoid valve situated & how does one check it out?
The injectors were cleaned today & the hesitation during acceleration has gone but the sparking is still there. The thumping noise (rough idle with AC on) was also less after the injector cleaning but is the same as before now.
Showed the car to another technician an hour ago. He interchanged number 3 HT cable with another (not sure which number). The sparking remains at the same spot. So it seems the cables are fine. Does this mean the ignition coil is to fault? Why should there be a spark at the coil end of the HT cable? I would have thought a faulty coil would not send any current out to the cable?
Going for another check-up tomorrow to the workshop.
Btw, do authorized service centers of automobile companies have the equipment to check injector flow rate & spray pattern or are there specialized workshops for this kind of work?

I like your questions! so, to begin with

1. The spark should only take place inside the engine, anyplace outside means your cable/insulation is breached. if he's changed the plug and the cable, and it's still sparking then your ignition coil needs replacement- not very expensive and you could try an old working one just to make sure. A faulty coil might send a spark if there's a small earth fault, if it were major, it would simply burn out due to the excessive current.
2. I'm not sure if your A/C has a solenoid valve or an electric clutch - this is what it does if I may elucidate - the compressor is always been driven by the belt, even if the A/C is on or off. When you switch it on, one of two things may happen - a) the solenoid coil which is bypassing the refrigerant shuts and the refrigerant is now pumped through the condenser/receiver, expansion coil, evaporator - basically, starts cooling or b) the electric clutch energises and starts to drive your compressor. Both are characteristically identified with a clicking noise when you switch the A/C on - here's what you do, start your engine, pop the hood, switch the A/C on and listen for that almost instantaneous click, with a small drop in engine rpm indicating that the engine is now driving the compressor - see when the thumping sound starts - immediately when you do this or after a while.
The thumping noise could have anything to do with either, since you did mention that it occured when the A/c is switched on.
3. No, authorised service stations don't do fuel pump work. they might be able to withdraw the injectors and do some what I call "thook lagao" cleaning, but it's only a specialized workshop that can calibrate the fuel pump. Injectors cannot be overhauled, they have to be replaced! Anyone that says they can be overhauled is probably talking about age old engines.
inorder to reduce the cost of the injectors, they are now just a use and throw issue.

[nura]

Thank you again @Otto.
The thumping noise while idling does not start as soon as I switch on the AC. It takes a little while & this duration is not constant. Sometimes it starts a few seconds after I have switched on the AC & sometimes it takes a little longer. I think the Santro AC has a clutch-driven compressor & my guess is it is working ok.
There is some information on the net on both "in-car" as well as "off-car" fuel injector cleaning. 3M seems to be marketing a product for "in-car" usage but I am scared to use it. A company called Autosonics is selling a machine for "off-car" petrol fuel injector cleaning. Tried to call them to find out if they have an installation in Kolkata but nobody picked up. Called up a Bosch car service centre in Kolkata & they said they do "off-car" cleaning - 600 bucks for the Santro.
Visited a cute little place near the office & they said they only do diesel injectors & petrol injectors are use & throw. Just like you said!

[razor4077]

Hey Doc,
In-car fuel injector cleaning basically means using some sort of fuel additive that is poured into a tankful of petrol. I have used the 3M product, and it's good to keep the fuel lines clean - but probably not the best to unclog injectors that are already clogged up tight in the first place.
I did an off-car cleaning of my Lancer's injectors - Alok Automobiles arranged that for me. As far as I know, none of the Hyundai workshops do off-car injector cleaning/spray pattern testing. If Bosch said they do it, go for it. 600 bucks seems reasonable enough. Makes a big difference - acceleration is smoother, flat spots reduced.

[sudheergodgeri]

Have you tried asking the service technician to look /check the belts - engine motor/gear/starter motor and confirm that the teeth on the rubber belt are not worn out/burnt out? That could make it loose pickup and miss (maybe "slip" on acceleration a little) ? I had a similar problem on my maruti after someone changed the head gasket when my engine had overheated and shutdown. Later when the belts etc/ were fixed /replaced by another mechanic, the car ran fine.

[nura]

Thanks @razor4077 & @sudhirgodgeri for your replies.
3M has a product (there are other brands in the international market as well) which needs to be used instead of petrol. A little complicated to use, highly inflammable, toxic to the eyes & skin & may not be able to get rid of stubborn residues. That is why I am not too keen to use it & am looking at the "off-car" options instead.
Here is a link to the 3M product.
Fuel System Cleaner Decarbonising
And here is a link to a lovely article on injector cleaning.
http://www.aa1car.com/library/2003/ic30336.htm
Will have the belts checked as well.
Just got a call from the workshop. They found the ignition coil to be defective & have replaced it. The injectors seem ok.
I guess I need to collect the car & drive it a bit to be sure.
Will post a report tonight.
Thanks once again.

[Otto]

Originally Posted by razor4077

Hey Doc,
In-car fuel injector cleaning basically means using some sort of fuel additive that is poured into a tankful of petrol. I have used the 3M product, and it's good to keep the fuel lines clean - but probably not the best to unclog injectors that are already clogged up tight in the first place.

Injectors will never clog internally, they almost always clog only at the exposed surfaces and especially if they drip - you'll have something called "crumpet" formation. But there is never a chance that carbon might get into the bores of the injector nozzle.
The idea of in-car cleaning is that the vapour formed with the petrol and the additive at that temperature will act on the deposited carbon and melt it - this would be seen by the high amount of black smoke your engine would produce for those first 15minutes.

Don't understand how your fuel lines would get dirty though


About worrying about using the product. I definitely recommend using it once. If it solves your problem, you know how effective it is, if it doesn't then there's no other choice now is there?

[razor4077]

@Otto: Wrong choice of words on my part. I meant the fuelling system as a whole, of which the injectors are a critical part. I am aware of how and where the clogging takes place. Thanks for the clarification though.

[nura]

I picked up the car from the workshop last night. The sparking has gone. So has the rough idle with AC on. They did not touch the injectors. Ignition coil replacement cost Rs1150.
@Otto
Can you provide some links to pictures of dirty injectors? All this while I was under the impression that the deposit was taking place inside the injector nozzle & restricting the orifice!