Starting problem, acts like no choke.
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Trailering
Joined: Dec 2011
Posts: 19
Likes: 0
Starting problem, acts like no choke.
1990 3.0L has symptoms, that in a carburetor world would be described as no choke:
It cranks fine, starts and runs nicely when warm, maybe on a warm summer day even starts without tricks. But on a colder day just wouldn't fire until it gets starting gas or a nice zip of gasoline down the throat. No codes. Could it be temperature sensor (ecu thinking it's always warm, even when it isn't)? And where would it be located on the engine? Is there a separate sensor for ECU and dash gauge?
It cranks fine, starts and runs nicely when warm, maybe on a warm summer day even starts without tricks. But on a colder day just wouldn't fire until it gets starting gas or a nice zip of gasoline down the throat. No codes. Could it be temperature sensor (ecu thinking it's always warm, even when it isn't)? And where would it be located on the engine? Is there a separate sensor for ECU and dash gauge?
Lead Driver
Joined: Sep 2003
Posts: 7,015
Likes: 208
From: SoCal
There are two temperature sensors connected to the ECU; one in the coolant passage in the front of the intake manifold, and an air temp sensor in either one of the air intake runners in the lower manifold, or in the air intake hose behind the MAF sensor.
There is usually also a temp sensor for the temp gauge installed near the front of the intake manifold, but it's different from the one for the ECU.
There is usually also a temp sensor for the temp gauge installed near the front of the intake manifold, but it's different from the one for the ECU.
Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
Replace the IAC, controls the cold start and hot idle rpms. Prevents dying.
Computer ECM controls idle by the IAC via PWM signal voltage pulses.
https://www.rockauto.com/en/moreinfo...t=6072&jsn=495
Also check throttle body plate and throat gap for dirt plugging. Clean
Dirty indicates defective filter, excessive blowby or PC valve leaking or leaking air filter box/tube
Computer ECM controls idle by the IAC via PWM signal voltage pulses.
https://www.rockauto.com/en/moreinfo...t=6072&jsn=495
Also check throttle body plate and throat gap for dirt plugging. Clean
Dirty indicates defective filter, excessive blowby or PC valve leaking or leaking air filter box/tube
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