im having idle problems with my 16v 4age.when i start the car when cold it idles at 2k as it shud but but is very lumpy and when it has warmed up idle stays at 1500 doesnt go below. any sugestions
It could be one of NUMEROUS documented issues.... (1) Look up how to put the car in diagnostic mode. When its in diagnostic mode, borrow a timing gun and confirm that the spark angle is at 10degrees. If not, adjust distributor until its there. (2) Try winding down the idle screw on the throttle body. First picture, its the recessed screw in the throttle body beside the TPS. If the car still sits at 1500rpm you can quickly check f its a faulty Idle Speed Control Valve aka ISCV. (3 this is the most likely cause) Remove your black intake pipe and air filter. Inside the throttle body on the bottom right is a hole. This is hole for your "choke" or "idle speed control valve". Put your finger over this and block it completely. There will be a lot of vacuum an you may pinch your finger, just man up. Your idle should now drop significantly, or may even cut the car out. Note the large hole at the throttle body inlet. Throttle bodys vary, but the hole WILL be there. {} This is your idle speed control valve. Note the hole you need to try blocking with your finger is partially obscured by the red circle in front of the gold throttle plate. {} What should happen is that when cold, the cold water runs through the throttle body ISCV. The two silver pipes on the left of the red circle are the pipes. As the engine gets warmer, the wax in the valve heats, softens and allows the valve to close. Or heats, expands and forces it closed. I cant remember. Air flows throught eh big hole in the throttle body, into the valve, and then comes out behind the throttle plate. When fully warmed, this valve should be COMPLETELY CLOSED! That is ther eshould be no vacuum at the big hole. When the valve is fully closed, idle can be set to 800rpm by using the screw on top of the throttle body. Otherwise the engine will cut out due to not having oxygen. If the Screw is wound down completely, and the idle control valve is working (no vacuum when fullly warmed) then your throttle plate is bent or needs its stop point adjusted. Or you have a vacuum leak from one of the myriad of hoses/inlet gaskets on a 4ag JDM import. This information is available on any 4AGE enthusiast website. Google this stuff or sign up to an enthusiast website and use the search button. Youll save time! Or if your ever down in Cambridge I can take a look for a few shillings.
thanks for the info mate much appreciated i tryed blocking the big hole in the throttle body and the car did cut out but also when the car was warm there was still vacuum from the hole does this mean a faulty iscv if so is it something that can be fixed without having to buy a new one.
If the hole draws vacuum and its been idling fully warmed for a considerable period of time then yes your ISCV is fooked! Replacements are not cheap at around 200quid from the states. You can try removing it and cleaning it when its cold. Also remove the idle set screw and clean its hole too. Ive done it before, it can help considerably. Alternativly, look for a second hand item from another toyota that uses the same waxstat valve. Most NA toyota engiens frmo teh time used it. Corolla GTis, 3SGE celicas (I think). Have a look around. Check your spark too as too much advance will keep your idle up. And a diagnostic can reveal other things that keep idle rpm high.
