How to Clean the IAC and Throttle Body on the 1997-2001 Toyota Camry 5SFE

Updated on June 30, 2020
hardlymoving profile image

Hardlymoving writes about do-it-yourself automobile maintenance on various makes and models.

A common but simple cold weather problem with the 4 cylinder 5SFE model Camry is the Idle Air Control (IAC) valve sporadically sticking. This value should close during cold engine start up to restrict air flow. Restricted air flow will provide a rich air/fuel mixture and prevent engine stalls. A rich mixture should normally result in a higher-than-normal idle speed (approximately 1,400-1,600 rpm). The rpms will drop as the engine warms up.

If your cold engine starts, stays at around 850 rpm, then eventually stalls, the IAC is stuck in the open position due to carbon and varnish accumulated by blow-by gases.

This buildup can be dissolved by spraying carburetor cleaner solvent into the IAC port, a small rectangular port opening in the mouth of the throttle body. You can access this port by disconnecting the throttle-body-to-airbox hose clamp, twisting and pulling the hose off, and then pushing the hose away from the throttle body opening. Apply a liberal amount of solvent in the port opening. Re-connect the hose and turn the engine on and off a few times to allow the IAC valve to work loose the carbon and varnish build up. As the solvent is being burned off, some smoke will blow out through the exhaust pipe.

If the above procedure doesn't fix the problem, consider replacing the IAC, which will require removing the throttle body assembly.

Camry I4 5SFE Throttle Body & Idle Air Control (IAC) Cleaning Video

This video will show you how to remove and clean the throttle body on Toyota vehicles with the 4 cylinder 5-SFE engine typically found on the older model Camry, RAV4 and Celica. Over time, the carbon buildup can make the throttle body plate "stick" resulting in engine response lag, the plate opening too much or too fast, and erratic idle.

Since the Idle Air Control valve (IAC) is attached to the bottom of the throttle body, removing the throttle body gives us the opportunity to clean this component as well. A stuck IAC valve will result in a too high or too low engine idle, rough idle, and engine stall during warmup. The carbon build up is the result of PCV and EGR gases being sucked in or injected into the intake manifold and backing up against the throttle body's throttle plate and components. To reduce carbon buildup, you can install an aftermarket oil catch can.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

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    • hardlymoving profile imageAUTHOR

      hardlymoving 

      5 years ago from Memphis, TN

      James,

      Could be a lot of issues ... but most likely your A/C unit engaging and disengaging to control your interior cooling temperatures. When it engages, it puts a load on your engine, the rpm's drop and the car's computer will compensate by raising the idle.

    • profile image

      James 

      5 years ago

      My Camry idle fluctuates after 30min (btw 800 and 900) especially in traffic. When I try to move the car goes off.

    • hardlymoving profile imageAUTHOR

      hardlymoving 

      5 years ago from Memphis, TN

      Psalm37,

      Doesn't matter if the car's an automatic or manual. The fast idle is controlled by the car's computer to enrich the air/fuel mixture (to prevent cold engine stall) resulting in high rpm's. The rpm's will gradually go down as the car warms up. I believe the coolant supply and return hoses to the throttle body allows the Idle Air Control valve (IAC) to monitor the engine temperature. As the temperature rises, the idle speed will diminish.

    • profile image

      Psalm37 

      5 years ago

      I also have an 01 Camry with the same fast idle. I plan to sub in a 5 speed manual, and would like to by-pass the fast idle, or at least bring it down by about 500 rpms. Is there some computer fix for this?? Thanks a lot!!

    • hardlymoving profile imageAUTHOR

      hardlymoving 

      5 years ago from Memphis, TN

      ajith,

      Yes ... that is normal until the engine warms up.

    • profile image

      ajith 

      5 years ago

      I have 2001 Camry v6. during start irrespective of outside temperature RPM will abe around 1500-1800 rpm. it takes 10 mins to come to normal rpm 700-800 . Car runs smooth is it normal ?

    • hardlymoving profile imageAUTHOR

      hardlymoving 

      7 years ago from Memphis, TN

      Not that I've seen. When they clog, rpm never rises ... and when the engine is cold, the car stalls until warmed up. You've probably have a vacuum leak. Check your Air Filter to Throttle Body Air Hose for cracks and all vacuum tubes.

    • profile image

      doug 

      7 years ago

      would the iac cause rpm flux during warm weather?

    • hardlymoving profile imageAUTHOR

      hardlymoving 

      8 years ago from Memphis, TN

      Stuck IAC valves are common on Camrys ... the fix is easy and straight forward.

    • profile image

      RUNXCTRY 

      8 years ago

      When starting my car in cold weather, my car starts, and the RPMs drop steadily within 3-5 seconds until the car stalls. I can rev the engine, hard, so that the idle controller (or whatever) kicks in and maintains steady engine speed.

      Can't wait to try this fix, then wait for a cold day.

      Thanks!

    • profile image

      david 

      9 years ago

      Just add this: I went to the Auto Zone have them use the handheld computer checked (because the engine light was on). The code number the computer give out is P0172 (nothing mentioned on the compter list to do with this process).

      The Symptom is: 1. the car stalls when I am driving from highway and stopps at the stop light. And 2. the car stalls when I start the car and back up while the car is warm (after driving for a while).

      Thank you hardlymoving !!!

    • profile image

      david 

      9 years ago

      I repeat the process ( exactly as hardlymoving mentioned ) 3 times. The result is ideal. Thank you hardlymoving !!!

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