Knocking

[SLK]

I have a WagonR, which knocks, and on hard acceralation it knocks real ugly.

I have got every thing done, what was possible, Injectors clean, new spark plugs, Valve Clearences, and in general tunning... but it doesn't stop.

The car has done 35k, in 3.5 yrs... and never been abused.

And i have also tried all the damn fuels... and system G.

Maruti has a standard answer,
1. a bit knocking is good for fuel economy (but my car is really bad at that too)
2. its due to poor indian fuel .. (Damn I have a AltoVxi same engine.. never knocks.. with any fuel)

Now Do you guys have anything more I can do?

And how bad is knocking for the health of the car? (i.e. can i just ignore it)

and guess what my last car also had same problem.. and no one could fix it!...

The reason I hear so much knocking is I never switch on the music system!

[Rehaan]

Hey SLK,

Well, the best way to solve this is by using a better fuel, but since you have tried that and it doesnt seem to help there could be a few other issues -

i- Get your engine knock sensors checked by the authorized service center. Maybe there is a malfunction and as a result the ECU isnt making the neccessary changes when there is knocking?
ii- Are you sure you are in the appropriate gear? for example if you are going up a slope in 4th gear there is bound to be knocking

"A bit of knocking is good for fuel economy" ......ummm.....in my opinion RUBBISH!!!!!! the way i see it, it would harm fuel economy!
Is it bad for the health of the car - yes it is, knocking over a period of time can do damage to the engine, and severe knocking can really mess it up real quick.

If i were you i would give the high octane fuel another shot... try speed 93(octane) if it is available. Also after putting that stuff in try disconnecting the NEGATIVE(black) terminal of your battery for a minute so that your ECU values reset and you have a fresh start with the new petrol for what its worth!

Let us know how it works out.
cya
Rehaan

[GTO]

SLK,

Knocking normally takes place when you are using fuel of a lower octane than your engine is designed for. That said, you have tried different types of fuel.

What I suggest is that you check the timing of your engine. A MUL workshop should take no more than 15 minutes to figure out if the timing needs to be retarded. Also as Rehaan stated, its a good idea to check your knock sensors and resetting your ECM.

GTO

[Shan2nu]

Yeah check the spark ignition timings. Octane is all about resistance to burn. So even if you have the right or better fuel quality, unless the spark timing is accurate, it won't help at all.

What about cracks or leaks in the cylinder? Can those be considered here?

This should help you understand the causes, symptoms and cure.

http://www.omegamotors.com/enjoy/gas...soline_07.html

According to this site """Compression Ratios around 9:1 and above typically call for premium fuel of octane 91 to 94""" a point to be noted here.........

Regards...
Shan2nu

[SLK]

Thanks that article was quite informative.

Now from all the things you people mentioned, there are a few I hadn't concentrated on.
Like the timing, and the 93 octane fuel and knock sensors (if any)

But do you guys have to use high octane fuel to avoid knocking?

Last time I went to Service station - Motorcraft (Maruti Masters) I got my valve clearances re-adjusted (they did it very unwillingly) and actually messed up, i can hear my valves all the time now. but that didn't affect the knocking.

So should I get it re-adjusted or just let it be, the way it is.

[Rehaan]

Hey SLK,

Give the 93 octane a shot and disconnect your battery after filling it so your ECU resets. This is basically the #1 solution.

" Do you have to use high octane fuel to avoid knocking? " - well it is the most practical as well as most advantageous solution. However since its difficult to get high octane fuel in india it is possible to avoid knocking using lower octane fuel, but the knocking is counteracted by altering the ignition timing, which does affect power and fuel economy adversely.

Might i ask why you got your valve clearances adjusted even though the service center were against it?

Also, i forgot to ask earlier, when does the knocking happen? Around what RPM? only when your goin up a slope? only at low rpm? etc etc

Try the 93octane fuel before anything!
cya
Rehaan

[kakx]

SLK,

Where u from, If BBY, i wld suggest u go to Sah and Sanghi, Prabhadevi workshop. Contact Mr.Shirish(Works Manager), Spk to him only and nobody else. He shd be able to help you.

Kakx

[Shan2nu]

If you car has knock sensors, then octane shouldn't really be a problem as the sensor detect untimed ignition and change the timings accordingly.

Regards...
Shan2nu

[GTO]

Hey Shantanu,

Dont you have a wagonR too? No knocking at all in yours?

GTO

[Shan2nu]

No knocking at all. It's smooth as silk.

Regards...
Shan2nu

[SLK]

hi,
Well I am in Delhi, so availability of any fuel isn't a problem at all.
Valve clearances are to be adjusted at the services but they never do it, so I got it done (well did more damage than any good)

When does the knocking happen.... It only happens on acceleration .. slight knocking on medium acceleration and bad/ugly knocking on pedal to the metal acceleration.

I don't need to use a high gear to check knocking it even happens in 2nd gear at speeds above 40km/h. It sometimes also happens while moving from standstill in 1st gear with a/c.

Normally it would happen more as the RPM increases. (strange!)
Say second gear without a/c... floor the acceleraton at 20km/h.... and the knocking will normally kick in by 40km/h. But if a/c was on ... it would start knocking from 20km/h....

[Rehaan]

Hey SLK,

Awesome avatar you have there......its like a tiny movie!
Try the 93+octane fuel and let us know, im really anxious to find out if that will solve your problem.

cya
Rehaan

[SLK]

ya as soon as my current tank-full (double dose SystemG) gets to a low level, I'll have Speed-93 filled. will take some time though.

the avatar is actually is from the movie Torque, the starting seen, but might get a bit heavy for some internet connections. and it won't be visible when my computer is not on!

[Rehaan]

Aah...is it hosted on your computer?

Why dont you upload it to imageshack.us or some other such site using these instructions, as it will prevent the site from showing that ugly red cross when you are not online!

cya
R

[SLK]

OK,.... guys here's the report after using speed 93 for over 1500kms in 2 weeks.
The damn car is really smooth now. It picks up like anything.
Well the knocking...
There is no knocking in the lowers gears now... like 1st or 2nd.
The 4th still is not perfect.... say if I accelerate hard and go to 85+ in 4th it knocks slightly. fortunately WagonR has enough torque to use 5th at that speed.

5th .. gear might knock when trying to go over 120km/h (its not very clear, engine coz of engine noise)

BUT with my kind of driving I hardly ever get to these extremes. So I am quite happy with the results.

The best part was .. when I first time got speed 93 filled the difference was instantaneous.