[headers]

Originally Posted by amit_mechengg

what i wonder is why will engine mounts have problem after the valve setting. there were no vibrations at all before i left my car in the A.S.S for valve tappet setting. will check the engine mounts again.

They are not connected, but if the engine mounts become weak, it translates into heavy vibrations at idle. Knowing Maruti and their Quality standards, I'm not surprised!

[scorpian]

I think the best and easiest solution out here is that u increase your idle rpm a wee little bit,so that the vibrations at idle reduce.

Trust me these A.S.S can be a real pain at times,i had a similar issue on my zen which would knock,did everything but no solution finally bought a timing light and checked the timing it was way higher thats what led to knocking.

So save yourself the trouble just increase it a little bit and that should make things just fine,am sure if you keep asking them to experiment you will end up with a much worser situation then you currently are,atleast thats what i went through.

[Ford Rocam]

Ask them to recheck the tappet settings & make clearance to oem spec. also check for IAC valve.

[anupmathur]

Originally Posted by amit_mechengg

One more thing which i doubt is the exhaust cleaning which has been done on my car. they have removed the CATCON. may be due to this the backpressure has reduced. Can it be that reduced backpressure causes engine vibrations?

Removing the catcon is bad practice, as your car will not meet emission norms now.
However, I do not think reduced back pressure of the exhaust would cause vibrations.

[amit_mechengg]

Originally Posted by anupmathur

Removing the catcon is bad practice, as your car will not meet emission norms now.
However, I do not think reduced back pressure of the exhaust would cause vibrations.

ya i know but as it is the catcon material was burnt out and was of no use. in Pune we get a PUC certificate even without taking you vehicle to PUC checking station.
i have observed a better pickup after the removal of the catcon.

[amit_mechengg]

i got my valve tappet setting done again.also checked the engine mounts and other parameters on tech2. still the vibrations remain.
the A.S.S people showed me other altos too and i found a similar vibrations on 2 more altos, however some were smooth.
so now i have decided to live with the vibrations, but the mystery of the hidden factor that is causing the vibrations remains unsolved.

[anupmathur]

Originally Posted by amit_mechengg

...but the mystery of the hidden factor that is causing the vibrations remains unsolved.

It's not really such a mystery: These 3 pot engines appear to have this problem at near the idling rpm. Please do not 'live' with these vibrations; get the idling increased by 50 or 75 revs to at least minimize them.

[vikram_d]

I just remembered this part. In the Tech2 what where the voltage readings for the Throttle Position sensor. For the Swift Petrol it is 0.8V. Get that checked as well.

I had a similar problem in my Swift (car was in NA form then) which started after throttle body cleaning. The problem was that the TPS was not set properly. Maybe this is the problem with your car also.

Ask them specifically, what is the voltage reading for an Alto on the TPS at idling and check if it is correct on the Tech2. This is the last thing I can think of.

Edit: Just spoke to my Maruti technician. He says that if idling is rough after valve setting that means the clearances are too tight. The clearance for an Alto with a cold engine on the Intake side should be 0.13 - 0.18mm and on the Exhaust side should be 0.21 - 0.26mm.

If clearances are OK then ask them to check timing. According to him, after valve setting the timing also needs to be adjusted.

Also the TPS voltage on idling should be 0.7 - 0.8V and this is common for all Suzukis' sold in India.

[amit_mechengg]

thanks a lot vikram, i dint check the TPS voltage.will get it checked again.by the way how did u set the TPS voltage? the gap set on intake valve is 0.15 . dont know about the exhaust. but this one is a MUL showroom and service centre. so these guys might have done it right. however i doubt their expertise.
the timing seems to be all right. the flash is seen exactly on the mark.

[vikram_d]

The sensor has slots where it is screwed on to the throttle body. You can loosen the screws slightly and rotate it with your hand till it shows the correct voltage and then tighten the screws back.

[Jaggu]

Originally Posted by amit_mechengg

hooked a TECH2 to my machine and checked the rpm. it was 898-908 i.e within the limits.

what happens is when i am driving and when i pull the gear to neutral on the signals or for a stop the engine vibrates, i feel the RPM goes down and again springs back. at constant idling the engine vibrates a bit.

what is this indicating? the throttle body is also cleaned twice. is it related to TP sensor or any other problem?

i am clueless and so are the A.S.S people.

Have you checked all the vacuum hose in the EFI circuit for any air leaks, asking since the RPM is dropping and springing back. Also check the throttle body setting, as mentioned above.

[vikram_d]

Originally Posted by amit_mechengg

hooked a TECH2 to my machine and checked the rpm. it was 898-908 i.e within the limits.

what happens is when i am driving and when i pull the gear to neutral on the signals or for a stop the engine vibrates, i feel the RPM goes down and again springs back. at constant idling the engine vibrates a bit.

After reading this part again I am kind of convinced that it is a problem with the TPS setting.

Also the normal idle for almost all Suzuki vehicles is 750-800. The Tech2 shows the desired idle as 752 rpm for the Swift petrol. Might be a little higher for the Alto as it is a 3 cylinder engine, hence vibrations will be a little more. But without A/C the normal idle will not exceed 800 rpm.

[amit_mechengg]

Originally Posted by Jaggu

Have you checked all the vacuum hose in the EFI circuit for any air leaks, asking since the RPM is dropping and springing back. Also check the throttle body setting, as mentioned above.

they checked the pipes near by the throttle body and the engine blow back gases pipe. they seemed to be fine. i will again ask them to check the vacuum hose pipe.
after the throttle body cleaning the RPM dropping and springing back problem has gone, now the rpm remains constant on idling, but there is lot of vibrations in the engine and the gear lever. and during normal driving when i press the clutch completely to get the car to neutral or to stop on signal, there is a peculiar sudden drop in rpm accompanied with vibrations and then there is constant rpm.

Originally Posted by vikram_d

After reading this part again I am kind of convinced that it is a problem with the TPS setting.

Also the normal idle for almost all Suzuki vehicles is 750-800. The Tech2 shows the desired idle as 752 rpm for the Swift petrol. Might be a little higher for the Alto as it is a 3 cylinder engine, hence vibrations will be a little more. But without A/C the normal idle will not exceed 800 rpm.

but on tech2 the desired rpm for alto is shown as 900 rpm. and the rpm on my alto is 898 to 910, i.e well withing the range.

[vikram_d]

Like I said, might be higher for the alto because of a 3 cylinder engine.

[drpullockaran]

Originally Posted by amit_mechengg

valve setting was done when the engine was cold. i had parked the car in the A.S.S the whole night and they did the setting in the morning without starting the car. they did the setting with the gauges provided by the company.

Valve settings are to be done with engine at operating temperature and very hot. This method will result in a lot of spilt oil in the engine bay but is the fail safe and perfect method.
After doing this check the compression pressure in each of the cylinders.

Next on the list is checking the voltage at the output of the spark plug cables. Get these done and then get back to me.

If your valve timing and spark timing and spark strength are perfect then you will not have vibrations even at 300rpm. Even if you do have vibrations it will be even and not go up and down the rpm scale.
You can imagine what I mean by the beat you can achieve in a well tuned Enfield350. The Enfield has a heavy flywheel to help it achieve that esquisite low rpm thump.