Engine Shudders During Cold Start Up

[Vertiga]

My car's engine shudders when start up in the morning. The shuddering can be felt through the steering wheel and it is not a continuous shudder but an irregular beat every 2 to 3 seconds. This symptom was already felt when the car was new but as the car ages, the effect is just more pronounced. After the engine's water temp is at operating range, the symptom disappeared. Changed the spark plugs and the problem was still there. Need to gather ideas on what could be the other components e.g. sensors, idle up valve etc contributing to this problem before I bring it into the workshop. Thanks everyone.

[Apollo]

cold start the ECU is on open loop, no sensor activate yet, it will prompt and activate all sensors, after a while then the ECU goes to closed loop.

 

cud b ur engine oil viscosity too low.

 

any knocking sound fr engine bay?

[Vertiga]

The engine oil viscosity is W40.

 

No knocking sound from the engine bay.

 

The shudder will start from the engine start up till the water temperature reaches near mid range on the indicator. There is an appox. 10 minutes of window period for the symptom to remain beofre it disappears.

[Dwoon]

Errr... if its any consolation... I've been having cold start symptoms for as long as I can remember (even worse than yours as I've jerky trans before warm up, have to wait half minutes after ignition is on before cranking else engine stalls, strong vibrations when engine is cold, etc)..... car hasn't fallen apart in the past 3 years..... so just learn to adapt to your car's temperament lor.... like let it idle for 3 - 5 min before you drive off......

 

oh.. if you're suspecting the oil grade.... then maybe you can try like 20W-50 to see if the symptom goes away..... The oil being thicker at startup might help???

Edited September 7, 2007 by Dwoon

[Apollo]

try not to switch on anything including headlamp, aircon and ICE.

 

see if that will b ok

[Vertiga]

Nothing switched on. Just start engine and let it idle and can feel the shudder. In fact, if air-con is swithched on, the situation is slightly better as the rpm goes higher to compensate for the demand, but the shudder is still there.

 

Any more thoughts, anyone?

[Apollo]

got Voltage stabiliser? or done CAI? got change air filter before?

 

looks like cyclic air intake or power supply fluctuation

 

unless beri old ride, then cud also b fuel filter.

[Vertiga]

Nope, no voltage stabiliser or CAI, stock air filter. Ride is only 1.5 years. But from day-1 the car was delivered, symptoms appeared.

 

Just thinking....could the air flow sensor located inside the air box be soiled/coated with dirt that causes this problem?

[Apollo]

cud be ur engine oil.. pressure not good.

 

hv it been scanned by OBD before?

[Vertiga]

Nothing shown up on the OBD.

[Yeobh]

Without make ,model & yr of car, it makes virtual diagnosing much more difficult.

For e.g some VW cars have two coolant temp sensors - one operating at low temp range the other at high temp range. If the low temp one is faulty you will exprience poor idling. Usually the problem will disappear once the high temp sensor cuts in.

Edited September 7, 2007 by Yeobh

[Vertiga]

YeoBH

 

The car is a Toyota Mark X, 1.5 years.

 

I would like to retract my initial information regarding the shudder being gone after the water temperature reaches operating range. This is because today, as I was waiting by the side of the road with engine running, music off, air-con off, I felt the shudder. But the amount is very minimal and I have to concentrate hard to feel it through the steering wheel. I guess that I am feeling the shudder now even as the water temperature has stabilized, probably due to the aging of the car.

 

Should I look in the direction of the water temp sensor or could there be a leak in my intake manifold? I would guess that if there is a air leak, then the idling will be rough and constantly existed instead of intermittent.

 

Thanks for responding.

Edited September 8, 2007 by Vertiga

[Yeobh]

Try inspecting all the vacuum hoses for loose connection or minute hairline cut.The other posibility maybe on of the spark plug cable has an internal facture that increase resistance to the flow of KV to the spark plug.

[Friendstar]

are u servicing with AD or outside wkshop?

 

 

edited: sorri saw ur mark x reply. ok ok got it

Edited September 10, 2007 by Friendstar

[Vertiga]

I guess inspecting of the vacuum hoses will not be too difficult. I will try using engine oil applied over the hoses and see if there is any white smoke coming out from the exhaust.

 

As for isolating the fracture on the spark plug cables, it might be a challenge. Any idea how to go about doing the check?

[Yeobh]

For vaccum hoses try pulling/ swing them while the egnine is running, if there is any loose joints , you will notice the engine rpm wil drop momentarily.

For the cables , it' s very easy, while the engine is running you can spray fine mist of water on the cables, any leak or minor short, the engine rpm will drop and maybe dies off.

The other method is to use a long thin stick, and tap and lift the cables, the same will happen to engine if there is any cable with internal damaged carbon conductor.

[Sky8807]

My suspicion is one of the plug is contributing this. I would suggest to change the spark plugs again. The right specification for the car model of course. Normal plugs of the right type will do.

[Vertiga]

With the stock factory plugs, the problem surfaced since the first day the car was collected. After changing to a set of new plugs, the problem still existed. Think this excercise of changing plugs is too expensive. A complete new set of 6 pieces of plug cost $260. I will look more closely into the plug cables.