P0300 Misfire in all cylinders 2001 Tahoe

[Nicolai8775]

GM P0300 Causes (* = Most Common)

• Faulty or worn spark plugs *
• Faulty spark plug wires or coils *
• Distributor failure *
• Faulty fuel injector *
• Vacuum leak
• Low fuel pressure
• Camshaft sensor defective
• Crankshaft sensor defective
• Engine timing off
• Leaking head gasket
• Low engine compression
• Poor quality fuel

With the work that you did you may have some problems with the cam or crank sensor.

Well I did lifters and pushrods stiffer springs and everything so now I'm worried about compression or leaky head gaskets lol.

And to be honest.. I'm worried about timing too. If all the dots are lined up right. Cam sprocket at 6 o'clock, crank sprocket at 12 o'clock. And the cam "pin" is at 3 o'clock on the cam sprocket. Is the #1 piston at TDC? We didn't do any of that process with the screw driver in the #1 piston hole to find TDC.

 

[ks03]

Having a new cam and intake, might hookup a vacuum gauge. If it’s too low, bounces or fluttering it might give a direction where to go, or hopefully eliminate mechanical issues

 

[OR VietVet]

Well I did lifters and pushrods stiffer springs and everything so now I'm worried about compression or leaky head gaskets lol.

And to be honest.. I'm worried about timing too. If all the dots are lined up right. Cam sprocket at 6 o'clock, crank sprocket at 12 o'clock. And the cam "pin" is at 3 o'clock on the cam sprocket. Is the #1 piston at TDC? We didn't do any of that process with the screw driver in the #1 piston hole to find TDC.

I have never done the TDC check with a screwdriver. I have #1 plug out and finger tightly over the hole and bump the engine till compression pushes finger off hole. You are on the compression stroke at that point. Line the timing mark on balancer with the TDC mark on the timing tab and you are TDC. If you set the cam and crank sprockets at dot to dot, they are correct. If you are just one tooth off, there is your problem. The dots would line up dot to dot with everything straight up and down at 12 and 6 o'clock. Vacuum gauge is great to hook up and get a reading. Normal reading would be a steady 18-22 inches at idle. You could have an intake not seated properly? Get a vacuum reading first. I like to take pics of major teardown work, now that I have a cell all the time. That way I can check for the timing marks align when an old fart like me asks.

 

[Nicolai8775]

I have never done the TDC check with a screwdriver. I have #1 plug out and finger tightly over the hole and bump the engine till compression pushes finger off hole. You are on the compression stroke at that point. Line the timing mark on balancer with the TDC mark on the timing tab and you are TDC. If you set the cam and crank sprockets at dot to dot, they are correct. If you are just one tooth off, there is your problem. The dots would line up dot to dot with everything straight up and down at 12 and 6 o'clock. Vacuum gauge is great to hook up and get a reading. Normal reading would be a steady 18-22 inches at idle. You could have an intake not seated properly? Get a vacuum reading first. I like to take pics of major teardown work, now that I have a cell all the time. That way I can check for the timing marks align when an old fart like me asks.

I may tear into the timing again then. But, before that, I did just notice a split in the insulation in the 1 wire for that camshaft position sensor.

 

[OR VietVet]

You might do yourself well by replacing the can and crank sensors and make sure all wiring is intact. make sure when you plug wiring back in that the wire stays encased in the connector tab and does not push out of the connector.

 

[Nicolai8775]

You might do yourself well by replacing the can and crank sensors and make sure all wiring is intact. make sure when you plug wiring back in that the wire stays encased in the connector tab and does not push out of the connector.

It's a 1 pin connector, can't find anything like it on oreillys site.

 

[Fless]

Aren't the cam and crankshaft sensor connectors 3-pin?

 

[Nicolai8775]

Aren't the cam and crankshaft sensor connectors 3-pin?

Well I guess that means I'm taking the intake off cause that wasn't the camshaft connect lol. But I'm confused. It's bolted downwards on the back of the block, behind the intake, what else is back there that I could have grabbed?

 

[Nicolai8775]

Aren't the cam and crankshaft sensor connectors 3-pin?

This is what I'm looking at.

 

[Nicolai8775]

Aren't the cam and crankshaft sensor connectors 3-pin?

Yeah you're right damn it. There's something else deeper down lol.