My engine stalls at idle?

It sounds like you have a vacuum leak, can you hear a hissing noise, please follow this guide to help you check for one, if it seems okay get back to me so we can continue.

https://www.youtube.com/watch?v=xN5pcM-5bso

Hi,

The black smoke is an indicator that the fuel mixture is too rich. Chances are it is related to the fuel pressure regulator. Do me a favor. Here is a link that explains how to test fuel pressure. Do this and let me know the results.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

https://www.2carpros.com/articles/engine-black-smoke

There could be other issues causing it; however, this is where I would personally start. Here are the manufacturer's specs for pressure:

2007 Chevrolet Impala V6-3.5L
Pressure, Vacuum and Temperature
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Fuel Pressure Specifications Pressure, Vacuum and Temperature
PRESSURE, VACUUM AND TEMPERATURE
Fuel Pressure (Key ON, Engine OFF) .................... 384-425 kPa (56-62 psi)

____________________________

If possible, let me know what code or codes were pulled. Often times I can tell what a more likely cause would be.

Take care and I'll watch for your reply.

Joe

There are a couple things that this could be. Most likely you have a vacuum leak. It is odd that it would only set one bank for the lean code, but I would start with this:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

The next thing is a possible throttle issue. However, your vehicle has an electronic throttle so it may just need to be cleaned.

https://www.2carpros.com/articles/throttle-actuator-service

I attached the info on this code as well. You could have an issue with an o2 sensor.

Run through this material and let me know what you find. Thanks

Welcome to 2CarPros.

Many things can cause an engine to stall at idle or when placed in gear. Engine vacuum leaks, a faulty idle air control valve (IAC), dirty throttle body, and so on.

With that in mind, can you tell me if the check engine light is staying on when the engine is running? If it is, I recommend scanning the computer to retrieve diagnostic trouble codes. If you are able to retrieve codes, it will point us in the right direction.

As far as possible things, here is a link that explains the most common causes of a stall at idle. Take a look through it and see if anything helps.

https://www.2carpros.com/articles/stall-at-idle

Also, here is a link that explains how to check for engine vacuum leaks:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Here are links that shows in general how to replace an IAC and service it. I would suggest removing it and checking for carbon build up or dirt where it mounts.

https://www.2carpros.com/articles/idle-air-control-valve-service

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

Let me know if that helps. Also, let me know if there is anything you can do to prevent the engine from stalling.

Take care,
Joe

How long since overall tune-up? Any applicable trouble codes? To check codes yourself, at the least you need an obd2 code reader. Did you visually check for spark, use a spark tester. Use a gauge and check proper fuel pressure. Also, check fuel injector pulse.

If start and stall, have to check security system. Is there a security lamp on the dash that is on or flashing?

Hello LAWANDA WILEY,

I am sending you some information to help you with the advise JDL gave you. These are links to a couple of articles form this site that feature written step by step instructions and pictures explaining how to do the scan yourself, also I have included a link to our YouTube channel with a how to video on code scanning. In addition I have included a link to another article from this site explaining the process of checking the fuel pressure yourself. If you decide you would like do this yourself you can purchase a fuel pressure gauge online from sites like Amazon.com. Most scanners are fairly inexpensive to purchase. Once you have the codes please get back to us so that we can further assist you. We are always happy to help.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

https://youtu.be/YV3TRZwer8k

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Thank you for visiting 2CarPros.com.

Kindest regards,

Renee
Admin

Ye, if the fuel pressure regulator is leaking, it would not hold fuel pressure and that would result in difficult starting.

Try turning the ignition on and off 2 or 3 times before attempting to start and see if there are any changes.

Check for any of the following conditions:

a) An incorrectly routed harness. Inspect the MAF sensor harness to verify that the harness is not routed too close to the secondary ignition wires or coils, solenoids, relays or motors.

B) A low minimum air rate through the sensor bore may cause this DTC to set at idle or during deceleration. Inspect for any deposits on the throttle plate or in the throttle bore and any vacuum leaks downstream of the MAF sensor.

C) Inspect for any contamination or debris on the sensing elements of the MAF sensor.

D) Inspect the air induction system for any water intrusion. Any water that reaches the MAF sensor will skew the sensor and may cause this DTC to set.

E) A wide open throttle acceleration from a stop should cause the MAF sensor parameter on the scan tool to increase rapidly. This increase should be from 3-10 g/s at idle to 150 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction in the induction system or the exhaust system.

F) A skewed or stuck TP sensor.

G) A skewed or stuck ECT sensor.

H) The barometric pressure used in calculate the predicted mass air flow value is initially based on the MAP sensor at key ON. When the engine is running the MAP sensor value is continually updated near Wide Open Throttle (WOT). A skewed MAP sensor will cause the calculated mass air flow value to be inaccurate and may result in a no start condition. The value shown for the MAP sensor display varies with the altitude. With the ignition switch in RUN position
and the engine OFF, 101 kPa is the approximate value near sea level. This value will decrease by approximately 3 kPa for every 1000 feet 305 meters) of altitude.

I) High resistance on the ground circuit of the MAP sensor can cause this DTC to set.

J) Any loss of vacuum to the MAP sensor can cause this DTC to set.

K) High resistance on the ground circuit of the ECT sensor can cause this DTC to set.

Problem could also be caused by aftermarket accessories.

Hello,

This is common when the throttle actuator needs to be serviced. here are two guides to help you fix the problem:

https://www.2carpros.com/articles/throttle-actuator-service

and

https://www.2carpros.com/articles/stall-at-idle

Please run down these guides and report back.

Hello,

This sounds like you have a crankshaft angle sensor that is going bad, When the engine stalls can you check it for spark, please follow this guide

https://www.2carpros.com/articles/how-to-test-an-ignition-system

and

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

Please let me know if you need anything else to get the problem fixed.

Best, Ken