engine shaking

[VectorX2]

recently my engine keep shaking during idle when its is fully warmed up, when i turn on the air-cond the shakings stops... what could be the problem?

 

[xtremeleo]

idle speed too low

 

[ragerunner]

Sifu xtremeleo, speaking of idle speed, I'd like to ask: why do some cars rattle and loosen things in the car like the dashboard when their engine idle rpm drops slightly lower (say, less than 700/800) whereas other cars (in my experience, Proton Perdana V6 and Nissan Sentra B14, both stock) can let their idle rpm drop to 500 or even less but still do not rattle?

 

[VectorX2]

idle speed too low

how to alter campro idle speed?

 

[xtremeleo]

how to alter campro idle speed?

dats the million dollar question sir, how indeed.. the thing is, i can introduce an external valve to tune the idle speed, but i think its unorthodox, lol.

Sifu xtremeleo, speaking of idle speed, I'd like to ask: why do some cars rattle and loosen things in the car like the dashboard when their engine idle rpm drops slightly lower (say, less than 700/800) whereas other cars (in my experience, Proton Perdana V6 and Nissan Sentra B14, both stock) can let their idle rpm drop to 500 or even less but still do not rattle?

iam no sifu sir, just an ordinary joe je.. back to the question, it depends on the dynamic stability of the engine, the placement of the engine mounts, power lap between the cylinders, etc. no two engines are the same, even if they use the same code. in ur case, u can go visit any proton service and ask them to increase ur idle revv, shud be easy for them. i highly suggest going to subang proton service center, behind the metro bus depot, near summit usj. they dont have too many cars there fyi, a good place nonetheless

 

[VectorX2]

haha, besides idle speed, what other things that could cause that, i also found that alot of white smoke coming out of my exhaust when it shakes...

 

[xtremeleo]

hmm, dat needs checking sir..

is it smoke, or look like smoke? water vapour is also white-ish, fyi. pm for more detail, tq sir

 

[ragerunner]

Thank you for explanation, xtremeleo Actually the Perdana and the Sentra are not the problem, these 2 cars don't rattle (the Perdana especially) even if their rpms drop to pretty low levels. My other two cars at home, a 1985 Toyota Corona with a 20v BT and a 1989 Honda Accord CA5 start to rattle when their engine rpms drop to less than 800. The Corona was like that even with the stock 4A carburetor engine. That made me wonder about the seemingly significant difference. At first I thought that it was due to engine age, ie. newer engine models are designed to be more rattle resistant, but the 20v BT is the same age as the GA16DE if not newer, no? The Perdana car design and engine is not new either. Got me thinking.. :hmmmm: But thank you for your explanation anyway..

 

[tks]

if memory serves...v6 engines are more balanced than I4's, and if (again) my memory serves...doesn't the 6a12 idle at like 600~700rpm...? :hmmmm2:

 

[VectorX2]

here is what my problem is....

when my car came out of the factory without any modifications... after it's first service, it's idle speed originally 600 rpm increased to 900 rpm, automatically...

then after a year driving... once in a while the engine shakes during idle... can feel the vibration throughout the whole body... but after a while idling the vibration stops... or when the aircond compressor runs, the vibration stops too...

after i changed the air filter to drop in and changed the exhaust, with the catalyst converter removed, each time it shakes, white smoke comes out of the exhaust, the exhaust becomes clear as soon as the shaking stops...

recently when i changed installed adjustable cam pulleys and and adjust the cam timings, the shaking dun just come once a while anymore, it shakes every time i idles when the aircond compressor goes off....

i wonder is this actually normal, or sumting when wrong in my upgrading process? or the engine already have a problem from the begining?

 

[tks]

brand new BLM idling @ 600rpm? thats already a problem...in the ecu its set to 900rpm. I'd say its time to let your mechanic check this out...

 

[VectorX2]

brand new BLM idling @ 600rpm? thats already a problem...in the ecu its set to 900rpm. I'd say its time to let your mechanic check this out...

i am actually tired of sending it to proton service center already ==" everytime i get useless feedback from them... wasting my time driving to the center...

my fc even fluctuate before between 10km/l to 4km/l before... but they didn't give me an answer... but eventually the fuel consumption goes back to normal after certain period of time...

everytime i ask them sumting is dunno dunno.... and tell me all sort of rubbish... i am kinds fed up...

but yeah, now tyhe idling speed is 900rpm...

even alot of mechanics i go to they would say they dunno how to solve the problem because they can't access the ECU...

what kind of problem am i actually facing?

 

[tks]

well, you should have thought twice before modding & voiding your warranty then eh? :) Neither would I have continued modding when you know something funky's going on with your engine...

If u want, I've got the diagnostics computer i could plug in. PM me.

Cheers.

 

[VectorX2]

but the thing is, already diagnosed a few times but it doesn't show any problems...

what other things that could be causing the engine to shake other than idling speed?

could be insufficient fuel? or izzit that the ECU is obtaining wrong readings from the engine speed where the engine speed is less than 900 rpm but the ecu thinks it is running at 900 rpm?

 

[xtremeleo]

sounds like a sensor contact issue jer.. u need to connect it to a diagnostic tool sir, i suggest u take tks' offer

 

[Veloc]

Thank you for explanation, xtremeleo Actually the Perdana and the Sentra are not the problem, these 2 cars don't rattle (the Perdana especially) even if their rpms drop to pretty low levels. My other two cars at home, a 1985 Toyota Corona with a 20v BT and a 1989 Honda Accord CA5 start to rattle when their engine rpms drop to less than 800. The Corona was like that even with the stock 4A carburetor engine. That made me wonder about the seemingly significant difference. At first I thought that it was due to engine age, ie. newer engine models are designed to be more rattle resistant, but the 20v BT is the same age as the GA16DE if not newer, no? The Perdana car design and engine is not new either. Got me thinking.. :hmmmm: But thank you for your explanation anyway..

Not rattle resistant. Actually every engines differs in their stability at low speed based on balancing, fittings, and construction materials. V6s are generally well balanced and smooth, hence being extra stable even at low speed.

About the vibration, your cars interior i.e dashboard, steering, switchgears are made from plastic, rubber, leather etc. Each of these are composed of particles (atoms or molecules) that have vibrational energy but you just do not feel it. Different materials have different particle vibration rate. Your engine that is running also generates vibration.

When you do not feel the rattling, this is when your engine's vibration is not in sync with the material's vibration. Meaning their vibration weakens or even cancle out each other. This is called destructive interference. Hence you feel smooth.

When you feel the stuff rattling, this is when your engines vibration is in sync with the material's vibration. The vibrational energy of your interior materials and of your engine builds one another up. thus vibrating the car more.

 

[VectorX2]

i went back to the workshop which did the cam degreeing for me... the mech says its normal that the engines vibrates that way... is it really that way? and sum how i seen some other cars that had their exhaust modified coming out the same 'white smoke'...

 

[tks]

good point Mr. xtremeleo. Siemens controlled wira came in today like an osim massage chair. no CEL but when plugged in diagnostics, >10 codes came out reset & cleaned up all the sensors and sent mr customer on his merry way...


as for you VectorX2...i think u need to find another workshop...unless your definitions have gotten lost in translation... Post a video! lets all see...

 

[VectorX2]

sorry for the late replies guys...

but somehow the problem... like went away... after i switch from ron 97 to ron 95... the engine even got quieter after using ron 95... isn't suppose using ron 97 makes the engine run smoother than ron 95? i even get better fc...

 

[xtremeleo]

dat was perculiar in the most perculiar manner vector-san, but iam glad to know ur problem is solved, even by just using a lower grade fuel. iam gonna dream of ur car tonite, lol