QuestionQUESTION: My car was experiencing a rough idle while in gear at a traffic light or stop sign. Even slowing down for a light or stop sign would cause a very rough idle and even a stall. The problems were happening as much as twice per week. I removed and cleaned the throttle body including the butter fly plate and all the holes I found in the throttle body.
Next, I removed the Idle Control Valve spraying TB cleaner through the holes in the top of the ICV into the chambers in the ICV. I also used a small screwdriver to move the valve that covers one of the holes closest to the ICV motor so I could spray cleaner down into the chamber. I couldn’t fit a brush into those chambers. I did not remove the small motor on the right side of the ICV or the round plate on the left side of the ICV that is held secure by two screws. I put a new gasket between the ICV and the throttle body. I also put a new gasket between the throttle body and the motor.
After cleaning as I mentioned above, the car did not have the problems as frequently but I am still experiencing the symptoms 2 or 3 times per month. The car starts normally in the morning before work or after work, but runs abnormally after driving about two miles. After driving those 2 miles and with the tach between 1200 and 2000 RPMs, the car acts like it has an erratic miss. When I slow down to about 1K RPM cruising or while approaching a stop sign/traffic light after the erratic miss, the idle will quickly fall to less than 500 rpm and want to stall. To avoid the stall, I put the automatic transmission in neutral and give some gas to the car to tack it up to 1K. This abnormal behavior doesn’t occur until I drive 2 miles like clockwork. The abnormal behavior sometimes occurs once every 5 days but other times the car runs correctly for two weeks before running abnormally. Other than these “abnormal days” the car starts normally and runs normally on the drive to and from work.
When I start the car in the morning, it tacks up to 1 or 2 marks (1,250/1,500 rpm?) above the 1 K mark. Then quickly falls to slightly above the 750 mark or slightly under the 750 rpm mark. I also notice that sometimes when the tach is around the 1 K mark the tach may rise by one mark (250 rpm) without me touching the gas. The rise falls back after about a few seconds.
One other symptom to note is that when I drive at 70 mph for say 90 minutes on an Interstate highway, the car will sometimes not idle as I slow down to near 1 K rpm to enter an off-ramp or toll booth. The car will stall but will start fairly easily after the stall but sometimes I have to depress the gas pedal to get it to start.
Ted, I can’t afford to replace the ICV for $250 if replacing it will not fix the problem. How can I determine if the ICV motor is defective? Do I need to further clean the ICV by removing the 4 Philips screws holding the motor on the right and the two screws holding the thin plate on the left side of the ICV and spraying throttle body clean in both the left and right ends of the ICV? Does the gasket between the ICV motor and ICV body need replaced? Lastly, is the erratic miss that happens between 1 and 2K rpm’s related to the ICV or what is causing that to happen? My Camry is a 1995 4 cylinder Toyota Camry with 142K miles.
Thanks for your insights, Ted! You are a wonderful blessing!
Sincerely,
ANSWER: In order to clean the IAC valve it has to be removed from the throttle body, do not remove the small metal plate on the bottom of the valve, clean the valve with spray cleaner and a small brush, remove all the carbon and make sure the small revolving door moves and returns to the almost closed position, do this first. I'm not sure if there is a misfire but after cleaning the valve if the misfire is still there it may be necessary to replace the spark plugs and the plug wires.
---------- FOLLOW-UP ----------
QUESTION: Hi Ted, thanks for your answer. As a follow up to your answer, I removed the IAC valve from the throttle body to clean the IAC in October of 2007. At that time, the small revolving door looked like it was closed. I was able to move that door easily so I could spray throttle body cleaner into the area/chamber under that door. I did not put a brush into the chamber under that revolving door or the chamber beside that chamber because my toothbrush did not fit in the hole. I sprayed TB cleaner into those chambers several times and used a low pressure air valve from an air compressor to blow out the residue.
Should I have removed the small motor from the IAC valve and sprayed cleaner in that end of the IAC valve too?
The erratic miss is not a miss that happens on a regular or daily basis. This erratic miss is short lived and happens about one minute before the car looses its ability to idle. The duration of this erratic miss is usually less than one minute. The miss is so soft that one might not notice it. The miss goes away after the first time the motor tries to stall. After that first attempt to stall, there is no more miss and the motor runs fine except when the rpm’s are 1,000 or less. The car wants to stall once it reaches 1,000 rpm.
This erratic miss was in the car before and after I cleaned the IAC. Before I cleaned the IAC in October of 2007, the car had the erratic miss and stalling problems occurring at least once or twice a week. After cleaning the IAC in October, the erratic miss and stalling only happened 5 times over three months on the 19th and 28th of January, on December 3rd and twice in November on the 9th and 13th or approximately two times a month.
Normally this short lived erratic miss only happens after driving the car for two miles, but in December the symptoms of the erratic miss followed by the loss of idle happened after driving the car 22 miles when the engine was well warmed up. The erratic miss disappeared after the car’s first attempt to stall.
In late August of 2007 I replaced the plugs with Toyota plugs, replaced the wiring with Auto Zone brand lifetime after-market wires, replaced the rotor and cap with aftermarket, and replaced the coil in the distributor with a genuine Toyota coil.
To sum this up, why would this short lived erratic miss happen before the car looses its ability to idle? The car runs fine before this miss happens. Why does the erratic miss usually happen like clockwork after driving about 2 miles? Why does the erratic miss disappear after the car’s first attempt to stall?
Where does one find a small enough brush to fit down into the chamber under the revolving door in the ICV and the chamber to the left of that revolving door chamber? Should I have removed the small motor on the ICV to spray cleaner in the hole where the small motor is attached?
Thanks a bunch Ted!
AnswerI sounds like you cleaned the IAC valve like it should be cleaned, I don't think it's the problem anymore, I'm wondering what the erratic misfire may be caused by, it doesn't sound like it's an electrical miss caused b spark plugs etc. It's possible that it may have a problem with one of the fuel injectors, try to use some sort of injector cleaner that can be added to the fuel tank and see if there is an improvement.
