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Hesitation and high Idle after cold start

Hi there, My car is a 1997 Toyota Camry LE V6
156,000 miles - hesitates when I am in traffic.
For example, in stop and go traffic I will come
to a stop slowly, and try to accelerate but
there is about a 1 second delay when I press
the pedal and the car goes. This doesn’t
usually occur at high speeds just low speeds.

More important issue:

Should also mention that when I turn on the
car on a cold start (it’s 80*F outside), it idles
at about 1,800 rpms. It doesn’t settle lower
than 1k rpms until I put it in gear or wait a
long time (5min maybe?) If I don’t wait for the
car to settle to 1k rpm, and I choose to put it
in drive, the idle drops from 1,800 to about 800rpm (normal I think?) And the car will “walk”
at about 5mph which seems and feels rather
fast because I am not pressing the gas, and
as soon as I do it will shift into 2nd gear
because it’s already traveling fast.

I has trouble shifting gears after cold start but not when the engine is warm.

It also is difficult to stop with brakes after cold start (because its “walking” fast)

Car runs fine and shifts good when warm after ive restarted the car (Ex. Going into a McDonalds and starting up car after 5 min away).

Car has no CEL codes
Car passes emission test with my OBDII
scanner(Blue Driver)

Recent Maintenance done:
New Battery

Replaced Spark Plugs and rear
wire set. (NGK)
New Air Filter
New Fuel Filter
Changed Transmission Filter (not flushed just
drained because ATF was black)
New Engine Coolant Temperature Sensor
Tried to clean IAC with throttle cleaner through bypass port.
Cleaned MAF Sensor with MAF Sensor
cleaner.

Could this be a bad Throttle Position Sensor, Idle Air Control Valve, or Oxygen Sensor?
Any help would be appreciated as I am a
college student and don’t have much money
to throw into parts.

The problem might be with a bad Idle Air Control valve.

A bad IAC valve won’t set a DTC.

The IAC valve controls the engine idle speed under all conditions.

It’s not the O2 sensor because the O2 sensor doesn’t come into play until the engine has nearly warmed up. And a bad TPS would eventually cause a Check Engine light.

Tester

1 Like

Hi Tester

I had the issue with a dirty IAC. I went ahead and replaced it (autozone) just to rule it out and no change has happened. I confirmed with a local mechanic that the IAC was working properly.

I am more concerned about the high idle, fast creep as if the car is “trying to get away from me,” and the higher fuel consumption at start up.

I am thinking vacuum leaks in either the brake booster, intake manifold, or O-rings on injectors?

Anyone have any other ideas?