Running Rough after Intake Gasket Replacement

[Spack9]

1996 K1500 5.7 I just finished intake gaskets but the truck is running very rough. Throwing P0106 for map sensor performace and P0300 for multiple random cylinder misfire. The truck ran great prior to teardown. From what I can gather from the service manual I expect a vaccuum leak. Gonna go try to track it down. If any of you have any insight it would be appreciated.

 

[GarrettGmc]

Have u checked the timing? Also make sure none of the lines got anything in them that would cause a clog.

 

[Spack9]

Im gonna give timing a check also. I just dont have the proper scan tool to get it spot on.

 

[slowburb]

Hopefully you used the ONLY failproof L31 intake manifold gaskets in existence, the felpro MS98000T. If you didn't, it's just a matter of time.

 

[Spack9]

Sure did! How did yaw go about getting the distributor adjusted using a scan tool?

 

[Spack9]

Got a P1345 code just a bit ago. Service manual says that means the distributor is installed incorrectly. So I pulled it gonna give it another shot later.

 

[east302]

Here are the diagnostics for the P0106 code. It may be something as simple as a damaged gasket where the MAP sensor snaps into the intake. I think the manual says to replace it if the sensor is removed.

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The P1345 is probably the CMP retard not being set correctly. Did you do that when you reinstalled the distributor? I wouldn't bother pulling the distributor if you didn't set that offset.

You can download DashCommand (buying the extended GM PIDs for your model as well) or CarGaugePro to get the CMP offset. You'll need a Bluetooth OBD connector as well. Maybe $50 for all of it.

It needs to be at zero degrees (+/- 2) at 1000-1200 rpm. Rotate the distributor until you get that value and then tighten down the hold down clamp. As a rough guideline, the distributor cap screw on the driver side will be very nearly touching the intake when it's set.




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[Spack9]

Thanks for the info! Currently I have 0.0 degrees to -0.8 degrees of cam retard. #5 and #7 cylinders are dead. Missing pretty bad. I am thinking I may have over tightened the rockers.

 

[east302]

Do you have spark at those two cylinders? Are you sure you got the wires right?

What else did you replace besides the lower intake gaskets? Did you pull the upper intake off as well...maybe reversed the 5 and 7 injectors?


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[Spack9]

I removed it as an assembly. I will recheck the wires and check for spark before I mess with the rockers. Also the distributor cap is new. I broke the old one installing it. Still curious about the MAP but I know it wouldn't cause what I have now.