My engine stalls at low RPM - idle

You can have a trouble code without the "Check Engine Light" coming on.
You may not have melted wires but if you do you will be looking in the starting and charging circuit. I am attaching wiring diagrams.
It could be a bad position snesor. I believe that gets talked about in the diagnostic walk through.

When battery died, it is equivalent to disconnecting the power source and that would result in computer losing memory. This would result in idling and performance issues. Try feathering the gas pedal to see if the engine continues running.

That means it is not an idling issue.
More like an MAF problem.
Check to see if there are any trouble codes stored.

Can you get a recording of what it sounds like when you are starting this? This could be a couple things so hearing it will help narrow this down.

Then we need to check for codes just to be sure we have none as that will cut down the diagnosing time.

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

Lastly even though we hear the pump, we need to check pressure while this is starting and then we will need to check to see if the injectors are cutting off by using a noid light.

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

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

I attached all these guides that will help with figuring this out. Basically I thinking there is an issue with the crank sensor and the PCM is cutting the injectors off so we need to prove or disprove that.

Thanks

Hi,

Listening to how it is revving up and down, the first thing I suspect is a faulty idle air control valve (IAC). The IAC is what is responsible for maintaining idle speed.

Here are the directions for replacement. However, before getting a new one, remove the old one and make sure there isn't a carbon build up in the throttle body and on the pintle. Also, if you have someone turn the key from off to on, you should see the pintle move.

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1997 Chevy Truck K Tahoe 4WD V8-5.7L VIN R
Idle Air Control (IAC) Valve Replacement
Vehicle Powertrain Management Fuel Delivery and Air Induction Idle Speed/Throttle Actuator - Electronic Service and Repair Procedures Idle Air Control (IAC) Valve Replacement
IDLE AIR CONTROL (IAC) VALVE REPLACEMENT
Throttle Position Sensor Electrical Connector

pic 1

pic 2

pic 3

pic 4

REMOVAL PROCEDURE
1. Remove the electrical connector from the Idle Air Control (IAC) valve
2. Remove the IAC valve attaching screws.

CAUTION: If the IAC valve has been in service: DO NOT push or pull on the IAC valve pintle. The force required to move the pintle may damage the threads on the worm drive. Also, DO NOT soak the IAC valve in any liquid cleaner or solvent, as damage may result.

3. Remove the IAC valve assembly.
4. Remove the O-ring.

CLEANING AND INSPECTION PROCEDURE
1. Clean the IAC valve O-ring sealing surface, pintle valve seat, and air passage.

Use the carburetor cleaner and a parts cleaning brush in order to remove carbon deposits. Follow instructions on the container.
Do not use a cleaner that contains methyl ethyl ketone, an extremely strong solvent and not necessary for this type of deposit.
Shiny spots on the pintle or seat are normal. They do not indicate misalignment or a bent pintle shaft.
If air passage has heavy deposits, remove the throttle body for complete cleaning.

2. Inspect the IAC valve O-ring for cuts, cracks, or distortion. Replace if damaged.

NOTE: If installing a new IAC valve, replace with an identical part. The IAC valve pintle shape and diameter are designed for the specific application.

3. Measure the distance A between tip of IAC valve pintle and mounting flange. If greater than 28 mm, use finger pressure in order to slowly retract the pintle. The force required to retract the pintle of a new valve will not cause damage to the valve.

MEASUREMENT PROCEDURE

NOTE: If installing a new IAC valve, replace with an identical part. The AC valve pintle shape and diameter are designed for the specific application.

Measure the distance A between tip of IAC valve pintle and mounting flange. If greater than 28 mm, use finger pressure in order to slowly retract the pintle. The force required to retract the pintle of a new valve will not cause damage to the valve.

INSTALLATION PROCEDURE
2. Lubricate the IAC valve O-ring with clean engine oil.
2. Install the IAC valve assembly.
3. Install the attaching screws.

Tighten
Tighten the IAC valve attaching screws to 3.0 Nm (26 lb. In.).

4. Install the electrical connector.
5. Reset the IAC valve pintle position.

5.1. Turn the ignition switch to the ON position for 5 seconds.
5.2. Turn the ignition switch to the OFF position for 10 seconds.
5.3. Start the engine.
5.4. Check for the proper idle operation.

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Let me know if this helps.

Joe

Sorry for the delay. When you updated the post it moves it back to the bottom of the list which is ordered oldest to newest so we were working on the older ones first.

Just so I understand, the engine starts and stalls immediately?

If this is the case the the injectors are being shut off as a way to cut the engine off.

The fact that you have 1 volt on the ground wire (lo reference) for the distributor could be an issue. I attached the info below on this wire. It is terminal A and is used to make sure there is there is a good ground.

Let's measure resistance on that wire from end to end with it unhooked from the distributor and ECM. It should be less then a half ohm.

Let's start with this and then we can start working through this. Clearly we just need to find why the ECM is shutting the engine down as it appears you have replaced everything involved so the ECM is getting a faulty signal somewhere to shut it down.

Have you checked for codes?

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method