[CYL]

Hi,
Just wonder why the car shakes when there is a rough idle?

I know that rough idle could be: spark plug, HPFP, injector, spark plug, vano, carbon built up in intake port, etc

But I am just curious what actually makes the car shaking? The engine shakes?

P.S. I found my car only starts having rough idle recently and the only mod that I have done is: golf tee...
injectors, thermostat, water pump, rocker cover gasket, OHG, have all been replaced in the last 6 months.

[CYL]

I read a lot that people are saying that they feel like there are only 3 cylinders working, or feel like 1 cylinder is not working etc.
I am also wondering how can they tell?
what sign should I be looking for? or what kind of feeling should that be if there is a cylinder missing?
same for people talking about engine stalling...I would like to know how to tell

I know it sounds silly, but I really have no idea of how..

[7smurfs]

Originally Posted by CYL

Hi,
Just wonder why the car shakes when there is a rough idle?

I know that rough idle could be: spark plug, HPFP, injector, spark plug, vano, carbon built up in intake port, etc

But I am just curious what actually makes the car shaking? The engine shakes?

P.S. I found my car only starts having rough idle recently and the only mod that I have done is: golf tee...
injectors, thermostat, water pump, rocker cover gasket, OHG, have all been replaced in the last 6 months.

Any codes?

I had similar issues went through 2 sets of new sparks (bosch & BMW), coil packs, carbon clean and the culprit ended up being injectors.

My car would fire up with rough idle and when i accelerated it would stutter for the first few kms before smoothing out. It was due to a leaky injector

[timot]

I'm no engineer but the gist is that rough idle generally equates to a misfire in a cylinder. And basically the cylinders need to fire in time to be in sync and in balance - as in, each firing cylinder generates a vibration but they're all set to fire in a certain order and timing so that they basically harmonise each other out so that it's buttery smooth.

So as soon as you get one cylinder not firing correctly it throws out the sync and creates an imbalance in the vibrations and thus you experience the irregular shakes through the car.

At least that's my understanding lol.

[CYL]

Originally Posted by 7smurfs

Any codes?

I had similar issues went through 2 sets of new sparks (bosch & BMW), coil packs, carbon clean and the culprit ended up being injectors.

My car would fire up with rough idle and when i accelerated it would stutter for the first few kms before smoothing out. It was due to a leaky injector

no code.
The next thing I am going to do is to check the spark plug.

leaky injector!?
Attached the previous service record for my car for your reference.
are you experiencing similar issues?

[CYL]

Originally Posted by timot

I'm no engineer but the gist is that rough idle generally equates to a misfire in a cylinder. And basically the cylinders need to fire in time to be in sync and in balance - as in, each firing cylinder generates a vibration but they're all set to fire in a certain order and timing so that they basically harmonise each other out so that it's buttery smooth.

So as soon as you get one cylinder not firing correctly it throws out the sync and creates an imbalance in the vibrations and thus you experience the irregular shakes through the car.

At least that's my understanding lol.

Thanks.
can I say that misfire is the same/similar to pinging?

[timot]

If you've already done your injectors, try coils and plugs next.
Nope misfiring and pinging are two different things. If your car was pinging you'd know. It should like rattling stones in your engine.

[DR-JEKL]

Vanos solenoids

[CYL]

Originally Posted by DR-JEKL

Vanos solenoids

Thanks DrJ
Yes. I know it could be the vano.
But I am curious why the car shakes if one of those possible parts is faulty.
Just want to learn the logic behind.

I want to learn how one part can affect the others.

[CYL]

Originally Posted by timot

If you've already done your injectors, try coils and plugs next.
Nope misfiring and pinging are two different things. If your car was pinging you'd know. It should like rattling stones in your engine.

I thought pinging is something like the fuel burns by itself but not by spark plug?
Which is similar to misfire?
Higher octane can help reducing chance to have pinging, right?

[waterbottle1]

i had rough idle for a while.. no codes

then several weeks later. BAM! misfire cylnder 6 and low pressure fuel sensor code.
then rough starts everyday from this day on. and never be able to pass 3000rpm before i throw a CEL light

I changed Lpfs first. This fixed the issue of getting past 3000rpm but then still followed by a misfire in cylinder 6.

when my coilpack arrived, changed that and everything is SWEEET again