ok so i have few queries to ask, but let me give a little background information. my liana was having problem of missing on 2nd gear and a littlw knocking on 3200 to 3400 rpm. below and above that it was ok. and knocking was more on 3rd gear and above. AC would make the knocking more audible. so firstly i cleaned the EGR valve. and when i was taking egr valve off, i broke the temperature gauge sensor and consequently had to buy a qabli for 400. egr valve was almost clean but still cleaned it up with carb cleaner. no improvement was found in car. so went to a mechanic, asked him to tune the car. placed new spark plugs(old one were in good shape too but still ) ngk brand. mechanic cleaned the throttle body by taking it off. cleaned the injectors rail and injectors. cleaned the IAC valve. after that tuning the missing on 2nd gear is totally gone. knocking is still there as it is. but after this tunning the car idle rpm was staying quite high, around 1300. resetting the ecu didnt do anything better. so went back to him and he adjusted it with a screw on TB and now idle rpm stays around 800.
ok so now the questions.
1) is there any way to check if egr valve is working? i asked mechanic to check with obd scanner but he said if egr wasnt working, check engine light will turn on. btw while cleaning egr valve, it would rattle a little upon shaking so i guess it is in working condition right?
2) what is causing knocking? he said bad fuel. ive got shims checked from another mechanic and he said shims are OK.
3) idle rpm is controlled by IAC. so by adjusting screw, he adjusted IAC?
4) when i first start my car on the morning, the car idle rpm stays around 1500, then drops to 1200 within seconds but then stays at 1200 for the time till temperature gauge reaches half mark. my question is shouldnt it start to maintain 800 with 2 3 mins? car has t stat installed .
please experts, help out!
PS: thanks for taking all the time for reading(if youve read all though :p)