Help,Idling Rough

[marvin guess]

I replaced the head gaskets on my 4.0 SOHC and got everything put back together and it fired and ran but is idling really rough and i beleive i hear the timing chain slapping on the left head. I think its the chain something is tapping. When i rev it up it smooths out then when it drops back to idle tapping starts.
Looking for opinions.

 

[poker4me007]

Probably have a vacumm leak somewhere...I don't know much about the sohc motor but did you replace the timing chains and guides when you did the heads?

 

[marvin guess]

No i did not replace them. Which i regret now. Thought i may get by without it but no dice! Im gonna be pulling the motor and doing it. I feel like the timing is off due to timing chain stretch.

 

[J_C]

I too suspect a vac leak, maybe just a vac line that wasn't reconnected or popped off and you didn't realize it. Considering head gaskets were done, I'd do a compression test if no vac leak found, though you should be able to hook up a scan tool showing live data to see if your fuel trims are high, as they would be if unmetered air is getting in.

What were the initial symptoms causing the head gasket job? Was a compression or leak down test done, or leaks observed? Have those symptoms changed significantly?