Engine shuts off while driving

On the throttle-body check the IAC(idle air control valve) you can try removing it and cleaning any carbon out of it, but if it's weak, a new one would eliminate the stall on de-cell or idle. IDLE CONTROL SYSTEM Idle Air Control (IAC) System Diagnosis) 1. If power-train OBD system check has been performed, go to next step. If power-train OBD system check has not been performed, perform power-train OBD system check. See power-train OBD system check test with codes - 5.7L article. 2. Turn ignition switch to LOCK position. Connect IAC Driver (J-37027-A) to IAC valve. Set parking brake and block wheels. Turn A/C off. Start engine and let idle. Using scan tool, display RPM. Extend and retract IAC valve using IAC driver. If engine RPM changes, go to next step. If engine RPM does not change, go to step 7). 3. If RPM changes smoothly with each flash of IAC driver between 700 and 1500 RPM, go to next step. If RPM does not change smoothly with each flash of IAC driver between 700 and 1500 RPM, go to step 7). 4. Disconnect IAC driver. Check resistance between appropriate IAC valve terminals. See IAC VALVE RESISTANCE table. See Fig. 3 . If resistance is as specified, go to next step. If resistance is not as specified, replace IAC valve and go to step 10).

5. Check harness between PCM and IAC valve harness connector for opens and shorts. If open or shorts do not exist, go to next step. If open or shorts exist, repair as necessary and go to step 10). 6. Check the following: mechanical malfunction, vacuum leaks, lean or rich mixture, poor connection at PCM, defective PCV valve, A/C compressor circuit for short to ground, poor connection at IAC valve or IAC valve passages for blockage or restrictions. If problem does not exist, go to step 9). If problem exists, repair as necessary and go to step 10). 7. Check IAC passages for blockage or restrictions. If blockage or restrictions do not exist, go to next step. If blockage or restrictions exist, repair as necessary and go to step 10). 8. Replace IAC valve and go to step 14). 9. Replace PCM and go to next step. 10. Connect IAC Driver (J-37027-A) to IAC valve. Start engine. Using IAC driver, extend and retract IAC valve. If RPM does not change as expected, go to step 3). If RPM changes as expected, system is okay at this time.

ya my 98 z71 i got it off a guy and he cut a hole in the bed to change full pump and he didnt get that seal in there so when it rained it got water in the tank so i dumped all the gas and water out of it put fresh gas in it and everything and went to start it and it cranks over and hes fire but it wont stay runing for about two seconds so i didnt know if there was water in the spiter ingection or what so i need someone to give me ideas of why it wont stay running and i need ot know why my headlight wont come on so can someone please help me with this ... thanks

Wow, I can't believe he did that........

Your going to need a fuel pressure gauge to get an idea what is happening here. It could be water or it could be a bad fuel pump too. You didn't mention changing the fuel filter and if you didn't, you need to do that right away.

I have a 1998 k2500 chevy with a 5.7 (350) vortec. The engine started to kill when I pushed the brake pedal or put it in reverse or pressed on the gas quickly. Icould slowly raise rpm if I was real slow on the gas pedal. Then it would not start anymore. I primed the engine with a little gas and then it would start and barely keep running and kill if I pressed the brake pedal or put it in reverse or quickly tried to reved it up. Now it only starts if primed and will not stay running. I changed the fuel filter and it was really bad. with a new filter the fuel pressure gauge I used to test pressure reads 50 lbs. I noticed in a manual that the norm is supposed to be 60-65#. I think maybe dirt got into the system? or something that I don't know about is causing this.. I would also like to know what the fuel pressure regulator valve that is shown under the top half of the intake manifold does?

It should still run decent at 50 psi the fuel pressure regulator regulates the pressure make the pressure higher when your engine is under a load higher rpms etc.Do you have any codes in the computer?

I don't know. can I buy a computer checker for this vehicle that will give me the code? ( I have a small one for my 2001 Camaro ) or can u suggest a way for me to get the error code ? Thanks joe

If you have a obd2 code reader that will read the codes on your truck.The one you used for your camaro should work on your truck.

While driving down the road my truck would just die, or stall, all the dash lights would light up and the last time it did this my radio clock was reset as if my battery was disconnected.

check to see if all your battery cables are tight and clean. also check all the engine groudns sound like theres a issue wit the cables causing the power to momentarely go out and go back on.

While driving, sometimes my engine will die and then I'm able to restart it after a few seconds. Sometimes I'll be just cruising and it'll die, other times it will die when I use a blinker or turn my lights on. It also varies, sometimes my dash will go completely dead, other times it'll stay illuminated. Any thoughts? Thanks in advance

Scan the PCM for trouble codes first. It may be fuel delivery, it may also be a loss of continuity at the power distribution center. Advise.

Thanks for your response, I should have mentioned before, the check engine light hasn't come on once since it started dying..

Does the dash illumination failure and the dying coincide?

Sometimes when it dies the dash will also go blank. Other times it will stay illuminated. Most of the time when it dies though it'll do it if I turn on my brights or the signal lights or if the ABS goes off.

after sitting for 24hrs it will start again then dies won.t start for another day have let it set for 5-6 hrs and tried still would not start.

Next time it dies, don't wait for nothing immediately look for fuel and spark if both okay-check engine compression

does not have spark after dying....does have fuel

Check and test ignition system components-start at coil/s-let me know

mine is doing the same but ive replace fuel pum, ignition coil, fuel pump relay and the same happens it will run and idle great for a while u can even drive it but after a lil while the TBI will not spray but if you hook it up direct it sprays need help...

Engine Performance problem
1998 Chevy Silverado V8 Two Wheel Drive Automatic

My 98 3500 with a 5.7 litre shut down on me on the highway. No spitting or sputtering. Just shut down. I replaced the ignition module. No change I replaced the fuel pump. No change.
I get spark, but it won't start.
Do Ihave to bleed the injector system or something? Should I get a computer check device?

You have verified fuel pressure with agauge? If so it may need a new crank position sensor.I have seen the sensors fail, as well as the wiring between the sensor and the computer.

Truck start, but will not keep running. changed fuel pump. fuel reg. silnoid.

Check fuel pressure even though its new if okay, clean out the idle air control valve and EGR and PCV valve and test the throttle position sensor-

Trucks stalls after driving. Will not start. Engine turns over fine but will not start. After sitting for a while the truck starts and runs fine. There is no lenth of time it has to run. Sometimes it goes weeks without issues. Any clues?

When the problem occurs, have a helper crank it, while you visually check for spark at the plugs. If you have spark everywhere, use a gage and check fuel pressure. Some of the national brand autostores used to loan out a fuel pressure gage, if you don't have one. You have to do testing when the problem is ongoing.

To test for spark at the plugs, pull a spark plug boot, use a known good plug or spark tester in the boot, ground metal part of plug/tester to metal part of engine, watch for spark.

The truck sat for a year, now it will start and idle all day but you put the truck in gear it will shut off. You then have to hold accelerator to the floor to get it started again and this might need to be done a few times.

Welcome to 2CarPros.

First, make sure nothing is blocking the air intake tube. If that is clear and the air filter isn't plugged, I want you to check the idle air control valve (IAC). The IAC is responsible for maintaining the engine idle speed by allowing a metered amount of air to enter the engine when the throttle plate is fully closed. What may be happening is when you take your foot off the throttle, the IAC may not be working and causing the engine to shut down and flood a bit. Then, you have to hold the throttle wide open to get it restarted.

I attached two pics indicating where the IAC is located. You will find it on the throttle body. First, make sure the electrical connector is clean and making good contact. If it is, remove the IAC and inspect it for corrosion, excessive carbon or dirt. Also inspect where it mounts on the throttle body to ensure it isn't plugged.

Here is a link that shows in general how one is replaced. I'm adding it so you can see what you are getting into before you start.

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

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Here are the directions for replacement specific to your vehicle. The remaining pictures correlate with these directions.

IDLE AIR CONTROL (IAC) VALVE REPLACEMENT
Throttle Position Sensor Electrical Connector

See Pic 3

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


See Pic 4

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.

See Pic 5

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.


See Pic 6

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 or if you have other questions.

Take care,
Joe