Hello guys,
I have a 2005-06 Toyota Corolla 1.6 VVT-i 81 kW (110hp) hatchback with 3ZZ-FE engine (with electronic IAC valve). I'm trying to fight these both problems and have no luck. When the car is started in cold ambient temperature (below 0C/32F degrees in winter) the engine idles about 1600 RPM for about 4-5 minutes before it slowly idles down. What is more mystery to me, today it was 17C/63F degrees and on cold start it got even up to 1950 RPM.. And another problem is when the engine gets to normal working temperature, the idle starts to be rough. RPM's drops till ~600 and it sounds like the engine will stall but after few secs RPM's go up to ~750 (and everything repeats).
What I have tried to do:
*Changed the intake manifold gasket to the orange one;
*Cleaned MAF sensor, throttle body with IAC valve, PCV valve (would have changed it to a new one but it costs about 40$ in my country to buy it from the dealer..);
*Changed the spark plugs to NGK (recommended in owner's manual);
*Found a few DIY's online and checked the ignition coil and fuel injectors resistance (all are the same), so I assumed they are not the problem here;
*Checked for fault codes via mini-VCI (none found);
*Tried to find visual vacuum leaks (none), is there another way to try to be sure?
*Changed the serpentine belt, oil, oil filter, air filters (if they can cause these sort of problems).
I've included a picture of live data (got from mini-VCI) when the engine is in normal working temperature and is on rough idle. Outside temperature was 17C/63F degrees. Is air intake temperature 35C/95F degrees not to high? And air flow 1,45 grams/sec (0,19 lb/min) not too low? Maybe you'll see something out of ordinary here.
What should I try next? Any thoughts are welcome.
I have a 2005-06 Toyota Corolla 1.6 VVT-i 81 kW (110hp) hatchback with 3ZZ-FE engine (with electronic IAC valve). I'm trying to fight these both problems and have no luck. When the car is started in cold ambient temperature (below 0C/32F degrees in winter) the engine idles about 1600 RPM for about 4-5 minutes before it slowly idles down. What is more mystery to me, today it was 17C/63F degrees and on cold start it got even up to 1950 RPM.. And another problem is when the engine gets to normal working temperature, the idle starts to be rough. RPM's drops till ~600 and it sounds like the engine will stall but after few secs RPM's go up to ~750 (and everything repeats).
What I have tried to do:
*Changed the intake manifold gasket to the orange one;
*Cleaned MAF sensor, throttle body with IAC valve, PCV valve (would have changed it to a new one but it costs about 40$ in my country to buy it from the dealer..);
*Changed the spark plugs to NGK (recommended in owner's manual);
*Found a few DIY's online and checked the ignition coil and fuel injectors resistance (all are the same), so I assumed they are not the problem here;
*Checked for fault codes via mini-VCI (none found);
*Tried to find visual vacuum leaks (none), is there another way to try to be sure?
*Changed the serpentine belt, oil, oil filter, air filters (if they can cause these sort of problems).
I've included a picture of live data (got from mini-VCI) when the engine is in normal working temperature and is on rough idle. Outside temperature was 17C/63F degrees. Is air intake temperature 35C/95F degrees not to high? And air flow 1,45 grams/sec (0,19 lb/min) not too low? Maybe you'll see something out of ordinary here.
What should I try next? Any thoughts are welcome.
