After cold start, RPM went low and died

[Aidan]

After cold start, my AUTO car's RPM drop and after a few seconds it started to vibrate, rpm went low and died.

 

What could possibly be the reason?

[Trex101]

After cold start, my AUTO car's RPM drop and after a few seconds it started to vibrate, rpm went low and died.

 

What could possibly be the reason?

 

Well, it would help alot if you can tell us your car model, age and mileage.

[Stanchiam]

have u do throttle cleaning before?

could be that it is dirty

[Aidan]

Well, it would help alot if you can tell us your car model, age and mileage.

 

06 Forester, mileage 87k. :)

[Pisces69]

After cold start, my AUTO car's RPM drop and after a few seconds it started to vibrate, rpm went low and died.

 

What could possibly be the reason?

 

Is yours injection or carb? Got ECU or not?

 

Maybe u got a small leak in yr fuel line/system cos when u park, the petrol drip/leak out n u end up with fuel starvation. Or fuel pump not working properly.

 

If u start again n blow blow a bit to prime yr fuel lines, did it start n keep running as normal.

 

If not, cud b yr auto choke faulty. Maybe some of your sensors dirty or need to change.

[Pisces69]

06 Forester, mileage 87k. :)

 

Or maybe your fuel filter clogged. When engine warm n u acclerate, is it smooth n powerful or jerky n no power?

 

Maybe u pump dirty SG petrol too long so got fuel system problem

 

I use clean MY petrol so dont hv any such problem.

 

Hv u changed yr original air filter to aftermarket performance type?

Edited March 21, 2011 by Pisces69

[Trex101]

After cold start, my AUTO car's RPM drop and after a few seconds it started to vibrate, rpm went low and died.

 

What could possibly be the reason?

 

I would suspect it's either throttle plate dirty, injector dirty or just plain old spark plugs that need to change.

[Heartbreakid]

After cold start, my AUTO car's RPM drop and after a few seconds it started to vibrate, rpm went low and died.

 

What could possibly be the reason?

 

This sounds like the idling servo valve not working. What it does? To prevent engine from suffocating during idling when throttle valve is at shut position, this idling servo valve will open and let air through a small passage to maintain the idling speed hence keeping the engine running. During air con compressor kicks in or out, the idling valve will help to maintain a stable rpm, e.g. at 1000rpm. If this idling valve is not functioning properly, the first thing one will know is during cold start, rpm will not shoot to around 1.5k rpm to warm up the engine, it will be at around 1k rpm or lower, and depending on the damage situation, the engine might not even start due to total air blockage. During compressor kick in, the rpm will be even lower till the engine vibrates and sometimes dies off, compressor kicks out, rpm will shoot to around 1.5k.

 

Let's see if what you face is what I have described, if so, that might be the idling valve problem, otherwise, you may have to check on other places. Do share with us the actual problem so we can learn from one another. Thank you.

[Aidan]

For my old car, workshop wanted to change this and that, I got a 2nd opinion elsewhere and in the end it was just changing of spark plugs.

 

Thank you for all your replies. At least I know what to check for this time.

[Smhomie]

Sounds like vacuum tubing leak, idle air control valve or air flow sensor malfunction.

 

If its spark plugs, you should have misfiring which is hard vibrations or tatatata noise coming from engine.

Edited March 21, 2011 by Smhomie

[Trex101]

For my old car, workshop wanted to change this and that, I got a 2nd opinion elsewhere and in the end it was just changing of spark plugs.

 

Thank you for all your replies. At least I know what to check for this time.

 

After changing the plugs, is there any stalling issue again?

[Mindfreak85]

i think maybe batt or spark plug

[Aidan]

After changing the plugs, is there any stalling issue again?

 

That was for my previous car. For this car, I will try chg spark plug 1st & see how it goes.

 

[Mona-vie]

Idling problem? Ususally due to either car running too rich during start up. This means either your idle valve not working properly or car misfiring. Is there black smoke coming out of the exhaust?

 

Try stepping on the throttle while running to try to maintain the RPM, does it help? If yes, then probably idle valve.

[Hulk]

So many reasons given over here, let me contribute one also: clean your MAF sensor

haha tell u best way is to send to w/s check.

 

[Hamburger]

no need think so much......just plug the OBD and analyze from there

[Wolfy3769]

any thing u had done recently to ur car?

 

part changes? mainteance work?

[Alvinlkw]

This sounds like the idling servo valve not working. What it does? To prevent engine from suffocating during idling when throttle valve is at shut position, this idling servo valve will open and let air through a small passage to maintain the idling speed hence keeping the engine running. During air con compressor kicks in or out, the idling valve will help to maintain a stable rpm, e.g. at 1000rpm. If this idling valve is not functioning properly, the first thing one will know is during cold start, rpm will not shoot to around 1.5k rpm to warm up the engine, it will be at around 1k rpm or lower, and depending on the damage situation, the engine might not even start due to total air blockage. During compressor kick in, the rpm will be even lower till the engine vibrates and sometimes dies off, compressor kicks out, rpm will shoot to around 1.5k.

 

Let's see if what you face is what I have described, if so, that might be the idling valve problem, otherwise, you may have to check on other places. Do share with us the actual problem so we can learn from one another. Thank you.

 

I had the same problem as well. Mine is a 06 Altis with 105k mileage. I just did a servicing and the guy told me that he cleaned up the throttle. He changed the spark plugs and battery so I have eliminated all other possible causes. This morning, the car was idling and RPM went very low and whole car was vibrating and nearly died. After that, I step on the accelerator to about 2000rpm for a couple of seconds and the vibration seems to be gone.

 

Also, I recently noticed that that vibration usually occur when I am about to come to a stop or idling at a stop. It won't vibrate as bad as this morning (likely due to cold weather) but just that I am concerned with it. How do I check on my idling valve?

Edited March 22, 2011 by Alvinlkw