Running Rough after Intake Gasket Replacement

[east302]

The diagnostics for that MAP sensor code end up with either a bad sensor or a bad wiring connection. If you didn't remove it from the upper intake (and possibly damage the little o-ring gasket on it), seems like it'd be a wiring issue. Maybe it didn't get plugged back in well.


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[slowburb]

Did you take to rocker arms off?

 

[Spack9]

It moved a good bit when I plugged it back in so I believe its time to replace the seal or just the whole thing. I don't think I have a vacuum leak, if I do its very little. Yes I did take the rockers, pushrods, and lifters out to clean and inspect all of them. I used the GM recommended no lash then one turn. After reading a little more people say thats a little too much for old parts.

 

[east302]

Did a compression test show the issue with 5 and 7?

Lack of compression, so I've read, could cause a false MAP sensor code.


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[Spack9]

Right before the gasket job I ran a test every cylinder was 195-205. If the rockers are too tight it will cause a loss of some or all of compression also. I'm leaning more and more towards that. I will recheck compression on them two and see if that is the cause. I have heard of ignition crossfire common between 5 and 7 also.

 

[Spack9]

Did some data logging also. The MAP is within acceptable range per the service manual. May be a residual code from when I found it loose.

 

[Spack9]

Update: Plug wires are installed correctly. Leaning towards injectors now. Gonna check for ignition and compression next.

 

[Spack9]

Success! Went back and readjusted the valve lash. Went with 1/2 turn past zero lash and she runs like a Swiss watch. Thanks everyone for your time and help!

 

[east302]

Good deal, glad you got it sorted out. Thanks for updating.


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