This is what happens:

I start my car and everything turns on okay. Now i am driving and as soon as i lift my foot from the accelerator pedal the rpm goes really down like around 100 or sometimes shuts off my car. Its really irritating, i can't brake properly cause then my car starts shaking like crazy because of the low rpms.

Initially my car had a 1600 CC engine (PK6 - Bought in Pakistan). I got it replaced with a D15B. This problem was there with my old engine as well.

I have been trying to find a solution to this problem for about a week now. Some mechanics said that there was something wrong with my cars idle air control valve (IAC) so i got it replaced however it didn't help. I got my electrical circuits all checked. Any help would be really appreciated. Thanks.

 

vac/pcv leak, brake booster check valve

 

could you please explain those abbrevations i am really a noob. The car gives no engine check light or anything. how can i know for sure which one is it ? And just so you know it stops doing it after i drive for like an hour or so.

 

you probably have a vacuum leak some where. The Positive crankcase Valve sometimes gets jammed up, causing a really low idle, or it might be leaking, stealing your vacuum.

@ idle, you have the highest vacuum, your car is calibrated for a constant vacuum leak through the PCV line. If this is clogged, the idle may become so low the car will shut off.

Otherwise if you have a FITV, fast idle thermo valve which i doubt, fix that too.

 

Your probably right and i will get these things checked today. What i don't understand is that why does the car statrs idling a little better after driving it for a while, say 1 hour or so. ?

 

Okay i got the pcv valve replaced. IAC valve is working correctly. My car has no FITV (Fast Idle Thermo Valve). I checked the pipe which connects to the brake booster and it had no leak. The engine seems to be in very good condition ... There are no leaks, the exhaust pipe is giving a clear transparent smoke, no shades of blue or balck. My car is still idling abnormally. I just don't understand how does it start idling correctly after it is drived for like 1 ~ 2 hours. Can anybody help me with this weird problem?

 

burp the coolant, something might be a miss in your coolant system

 

I have the coolant in my radiator pipes. The car reaches the normal temperature within 5 mins and stays there ... I don't know what could be possibly wrong with the car now ... anyone ?

 

Oh yes and my car doesn't gives any check engine light. Could anybody help me with this little problem ?