[rajismine]

Hello friends...Hope I am in the right section for this topic...

Could not find info on other threads hence a new one.

I recently bought a Used 2004 Chevy Optra 1.6 petrol, with 53K Kms on the odo

The car is neat, starts in a second in cold mornings, drives well and has no other issues but this one:

"The car suddenly starts jerking when in 3rd gear and at times 2nd gear also". It drives well and suddenly on accelerating starts jerking. If I leave the accelerator and press again it drives well again.

Its very irritating at times especially when family is in it....

Someone told me it happens if there is clogging in the injectors...is this true?

I also see a a very little oil deposit on the engine...may be like 30-50ml on 1000kms that I have had it for...I checked engine oil level and it seems fine..

so please help on on this:
1.) Could it be because of Clogged injectors?
2.) Could it be because of bad Spark Plugs?
3.) Is that oil leakage normal?
4.) Is it something that may require immediate attention?

regards

Rajeev

[Lukeskywalker]

Hi Rajeev, my Optra too experienced this right after a costly 60k scheduled service, I initially suspected HT cords (the wires connecting the spark plug) but on a thorough inspection by the A.S.C, it was diagnosed to be the HT coil which had given up. Once it was replaced, the problem was solved.
If you are lucky it could just be the vacuum tube which has a leak, or maybe the HT cords, these are relatively cheaper than the coil itself.

[mooza]

Similar thing happened in my petrol Ikon recently, checked the HT cables first, did not solve the problem, later turned out that the ignition coil had gone kaput. Spent around 6k on it, and everything was purrrfect

Keep us posted.

[jeeva]

Same was the problem with my Palio.
HT wires were the culprit again. Also, check the spark plugs.

[dhanushs]

Its usually ignition coil faliures that give out strange jerks and misfiring.

Originally Posted by mooza

.. Spent around 6k on it, and everything was purrrfect

If I remember it right, I spent around 4.5k for the same. Did you change the cables too?.

[mooza]

^^Yes, they changed a cable too, in the process, as one of the circuits was not firing, plus the labour. Still, I agree 6k looks a bit steep compared to your expense.

[rajismine]

tx a ton guys.....will keep you all posted..

here is what I have planned so far:

Steps:
1.) Clean Air Filter
2.) Check Fuel Filter
3.) Check HT Wires, HT Coil and Vacuum Tubes
4.) Check Spark Plugs
5.) Check MAF Sensor
6.) New Engine Oil
7.) Use Speed Petrol for at least 2000 Kms

[dhanushs]

^^ Please add - Pressure Clean/Check fuel pump, to that list.

Also, while checking the fuel filter, you can get an idea if adulterated fuel is the culprit, if so please clean the injectors/fuel lines/tank too.

[rajismine]

Update 1...so far got time only to get the Air filter cleaned....and have not experienced the problem so far...though have driven it only 2 Kms after that:-) will keep you all updated with further progress

tx

Rajeev