1995 Chevy Silverado engine stalls under load

Tiny
TEXANMP
  • MEMBER
  • 1995 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
The engine runs great in park. As soon as you transfer it over to drive or reverse it stalls out and misfires. Here is a list of replaced parts. Spark plugs and wires distributor cap headers intake manifold o2 sensor water pump oil pump fuel sending unit with fuel pump and fuel filter. New head gaskets fuel injectors. This truck runs fine until it is under a engine load. My last option that I could think of was the transmission vacum moduale. Could it have a vacum leak. The aftermarket intake is pulling in 10 times more air than it should. Injectors are spraying healthy. Any help would be appreciated.
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Monday, September 29th, 2008 AT 9:40 PM

5 Replies

Tiny
KHLOW2008
  • EXPERT
Hi texanmp,

Did you get the year correct? I believe Silverado was manufactured only in 1999.

Can you please provide the engine and trans model to enable me to get the necessary info.
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Tuesday, September 30th, 2008 AT 9:00 AM
Tiny
TEXANMP
  • MEMBER
1995 Chevy K1500 5.7L 4L-60E
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Tuesday, September 30th, 2008 AT 5:50 PM
Tiny
KHLOW2008
  • EXPERT
Hi texanmp,

When engine stalls/misfires under load, it should not be caused by the trans. I believe the problem you are facing is engine performance related.

Did the problem occur before the head gasket replacement?
What is the idling rpm?
Does the engine idling rpm drop/fuctuate with AC turned on/off.
Did you
1. Do a compression test?
2. Check the ignition timing?
3. Check valve timing?

The trans is controlled by the PCM and operated by solenoid switches so there are no vacumn lines to cause idling problem.
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Tuesday, September 30th, 2008 AT 8:39 PM
Tiny
TEXANMP
  • MEMBER
The motor was running fine before. I did a compression test and all 8 were running between 120 and 140. The idling rpm is right at 800. The timing has been checked several times and it is dead on. I will have to get back to you about the a/c running and the valve compression test. If the head gaskets were not properly sealed would that cause this problem? What would be the proper way to diagnose this problem? Could I just start with the heads off and work from thier? This is definately a performance problem. Could this be related to a sensor gone bad or the computer just not registering the changes?
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Wednesday, October 1st, 2008 AT 3:19 AM
Tiny
KHLOW2008
  • EXPERT
Hi texanmp,

Start with the compression test first.

Improper sealing of the head gasket would cause compression problem. Insufficient valve clearance would cause compression losses as well.

Are there any coolant losses problem? That would indicate gasket problem.

Before removal of head you should confirm the source of any malfunctions.

If any sensors are bad, the Check Engine Lamp would illminate. Get a scan done to confirm this.
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Wednesday, October 1st, 2008 AT 7:20 AM

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