Truck runs fine when on gas but idles to low around 500 to 300 rpm then dies. i just rebuilt the throttle body and put new throttle position sensor, air idle control ,and new injectors in it. not sure what to look for now other than a vaccum leak
HI
Description
The engine control module (ECM) learns the idle position of the throttle plate to ensure the correct idle. Anytime the throttle body is cleaned or replaced, the ECM must learn the new throttle position. The idle may be unstable or a DTC may set if the throttle position is not learned.
Conditions for Running the Throttle Learn Procedure
• DTCs P0101, P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0506, and P0507 are not set.
• The engine speed is between 450-4,000 RPM.
• The manifold absolute pressure (MAP) is greater than 5 kPa.
• The mass air flow (MAF) is greater than 2 g/s.
• The ignition 1 voltage is greater than 10 volts.
Throttle Learn
Important: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code
(DTC) List - Vehicle.
1. Start and idle the engine in PARK for 3 minutes.
2. With a scan tool, monitor desired and actual RPM.
3. The ECM will start to learn the new idle cells and Desired RPM should start to decrease.
4. Ignition OFF for 60 seconds.
5. Start and idle the engine in PARK for 3 minutes.
6. After the 3 minute run time the engine should be idling normal.
Important: During the drive cycle the check engine light may come on with idle speed DTCs. If idle speed codes are set, clear codes so the ECM can continue to learn.
* If the engine idle speed has not been learned the vehicle will need to be driven at
speeds above 70 km/h (44 mph) with several decelerations and extended idles.
7. After the drive cycle, the engine should be idling normally.
* If the engine idle speed has not been learned, turn OFF the ignition for 60 seconds
and repeat step 6.
first I would like to tell you, do this procedure only if the 5th digit of your VIN is C or K.
8. Once the engine speed has returned to normal, clear DTCs.
Good Luck
SOURCE: 1992 gmc chevy 350 wont idle when warm
This could be a number of things but i think that your problem sounds like a vacuum leak or an EGR problem. Try listening for leaks and try un-plugging the EGR solenoid valve one time.
SOURCE: 95 GMC Sierra 4x4 350 5.7 rough idle problem
It sounds like a MAP sensor going bad. MAP is short for manifold absolute pressure sensor, it senses the manifold pressure and applies the right amount of gas with the right amount of ignition timing so the car runs and performs well if this does not work properly. It throws off the whole loop cycle for the computer, which in turn makes it run badly and get poor fuel economy. It can causes the engine to have a lack of power, combined with a loss of fuel economy. Poor take offs and sometimes an occasional stalling may occur if the MAP sensor is faulty and sending the wrong signals to the ECM.
Hope this helps and thank you for using Fixya.
Here is a link that my help you in the future.
http://www.troublecodes.net/GM/
SOURCE: 2003 GMC Sierra Has recently developed
You never replace anything, on a Wishing,Hoping,Pushing,Poking,diagnostic approach
You learn the vehicles Systems,Test,then Replace,if you have a failed component.
Work on the Misfire Issues.
Then you lean O2 Codes will go away.
Not a the plugs.
Think lean---Vacuum leaks,EGR Valve leak,EVAP System leaks,anything with a hose that lets air into the intake system.
Exhaust System leaks,near sensors
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