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Chris (aka-Moose)
Chris (aka-Moose), Auto Technician
Category: Toyota
Satisfied Customers: 947
Experience:  16 years of experience
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2001 toyota echo: I have a Toyota 2001 echo that idles too

Customer Question

I have a Toyota 2001 echo that idles too fast when hot. I just changed the IAC, cleaned the throttle body and regasketed both of them
Submitted: 2 years ago.
Category: Toyota
Expert:  Skyvisions replied 2 years ago.
Do you still need assistance on this issue?
Customer: replied 2 years ago.
Expert:  Skyvisions replied 2 years ago.
Do you have an active testing scan tool? Did you check for vacuum leaks? What is the RPM at warm and cold?
Customer: replied 2 years ago.
I do have a scanner. I have not checked for vacuum leaks, but did replace the 2 hoses going to the rear of the IAC. What is their function? It appears that coolant is going through them an just passsing through a closed chamber at the IAC.
The car does not have a tachometer, so I can only guess. I would estimate normal idle of 700-900 cold, and 1500-1700 when hot.
Customer: replied 2 years ago.
The only scan code that is coming up now is P505. I did have several other codes, P441, P446, that have to do with the charcoal vapor canister, but they have been showing up intermittently for some time now and I assume have nothing to do with the idle issue.
The P441 and P446 codes cleared when erased, but the P505 did not. I replaced the IAC with a new Airtex unit purchased from Rock Auto. New gasket on the IAC and throttle body, which I cleaned.
Customer: replied 2 years ago.
This car has a 5 speed manual transmission.
Customer: replied 2 years ago.
One thing does come to mind. I replaced the original clamp on the big air breather tube going to the throttle body with a regular stainless steel band clamp. I really mangled the old OEM one getting it off. Is it possible that bit of air is leaking by here and allowing some air around the Mass Air flow sensor?
Customer: replied 2 years ago.
The car runs beautifully other than the high idle when hot. Much better acceleration, smoother than before replacing the IAC and cleaning the throttle body.
Customer: replied 2 years ago.
It almost seems like the IAC is working backwards. Higher idle when hot than cold.
Expert:  Skyvisions replied 2 years ago.
The coolant hoses going to the idle air control valve are designed to heat the idle air control valve up so that during the wintertime it does not freeze or get ice in it and also it helps bring the spring tension off of the idle speed control motor. The computer duty cycles the on off time of this Rotary valve to control the idle speed. The P0 505 code sets whenever the engine control computer cannot maintain a target engine idle speed. The mass airflow sensor boot leaking air should not cause this but you need to confirm that it is not leaking by spring carburetor cleaner around the boot and clamp if the engine RPM increases or starts to falter than the clamp is leaking. On a mass airflow system it will not cause the engine idle to rise up but typically will drop down when there is an intake leak after the mass airflow sensor. Do you have a voltmeter to check the voltages or duty cycle percentages on the wires going to the IAC?