My truck will not idle down. I have tried everything. A friend has a salvage yard and I have swapped about everything: Entire throttle body with sensors, Cam position sensor, Crank position sensor, TPS, IAC, ECU. The only one i havent done is the O2. I have rechecked the timing belt after I changed it and it is correct. It was fast before the change as well. I have sprayed all over the intake and all hoses looking for vacuum leaks and cant find any. I GIVE UP!! Somebody else try. Thanks.
You could have a bad or disconnected temperature sensor. This would make the ECU think the engine is cold constantly and kick in the cold idle motor. Have you verified the linkage isn't the problem by unhooking while idling. Dirt and gunk under throttle pedal will somtimes cause it to stick. HTH, davidj92
Yes, the throttle plate is closing and I have replaced the coolant temp sensor. Forgot to mention that one but it was the first one to replace. It runs around 1100. The a/c switch is off and the power steering idle up is not it either because when you turn the wheel it will speed up some more, the same with the a/c.
If throttle plate is closing completely then I would look at cold idle system. I'm not sure which system Toyota uses, there may be something stuck open keeping engine in high idle state. I'll have the time to look in service manual tomorrow and post any additions. HTH, davidj92
It is showing on a scan tool about 57% Idle air speed open which seems very high to be warmed up. I have tried two different Idle valves but no change. I removed the cover of one of the valves to get access to the little knob that turns by the motor of the valve. You can turn the knob and it will idle down to the point it will stop running which leads me to believe I don't have a vacuum leak. Thanks for the help!
"RobertM" wrote in message news: snipped-for-privacy@localhost.talkaboutautos.com...
Unless there is an electrical control seeing a low vacuum then I would agree. I just read a post in Camry ng about a sticking slide in a idle control valve. His problem was a stumble and low idle speed but a sticking slide could cause the opposite, high idle speed. He cleaned with TB cleaner and problem recurred. He lubed with TriFlow aerosol lube for bicycle chains (PB Blaster has a good chain lube as well) that doesn't attract dirt and problem solved. I attached his message JIC it might help you.
--------------------------------------------------------- IAC is the idle air control valve. This discussion relates to a 1994, 4 cylinder Camry. Seems operation of this valve is a recurring problem. Best information I could find on the Internet was to spray emission control safe carburetor cleaner in the small square orifice at the front/ bottom of the throttle body to restore operation, or replace the valve. Problem manifests as stumbling low idle when first starting up in the morning, that is, the automatic fast idle for the cold engine doesn't engage. If you put it in gear like that, it dies. For the first couple of years, the carburetor cleaner worked fairly well. Remove one hose clamp, short burst of spray, turn the ignition switch on and off a few times, to try to force the valve to move and all would be well for another few months. Then the "cure" started to fade and the problem would recur within a few days. So I ordered a new idle air control valve and throttle body gasket and consulted the Factory Service Manual. The procedure for throttle body removal included procedures for adjustment of the TPS (throttle position sensor), instructions for cleaning with solvent and compressed air, and procedure for calibrating a vacuum diaphragm which controls the butterfly throttle plate. One of the vacuum ports had been at least partially blocked - now cleared, the .012" setting on the TPS was off, and adjusted per spec., and the idle speed at the vacuum diaphragm with the line removed after reassembly required adjustment. I did all of this. Since the old IAC valve was going in the trash, I disassembled it for examination. There is a bimetallic thermostatic coil on one end of the shaft and a round permanent magnet on the other end. The cylindrical part with the port that moves to progressively open or close had a small groove worn in it as if there had been some contamination or binding. All was well for about six months until the rough idle at cold start returned. Finally, the idea presented that there is no lubrication for that valve. Have been using TriFlow aerosol for the electrically powered antenna after seeing this specialty lubricant in a bicycle shop - for use on chains and cables, to lubricate without attracting dirt.
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I sprayed a small amount of TriFlow into the IAC valve on the theorythat perhaps that bimetal thermostatic coil is supposed to rotate theIAC valve when cold, and if it sticks slightly, the spring pressure maybe insufficient to move it. The permanent magnet on the other end mustbe part of the computer controlled step motor that adjusts idle speedcontinuously to maintain the target value.Works great. Idle speed when cold is very "fluid", that is, rises justfor an instant then settles slightly and adjusts downward as the enginewarms, just as it should.So perhaps this is the solution for what appears to be a designweakness in an otherwise superbly engineered vehicle - a way to keepthat valve moving smoothly without gumming up or attracting dirt.We shall see.
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