Replaced Head Gaskets got some codes.

[Explodr94]

Exploder, 1996 4.0 OHV, is running, but rough idle. New gaskets up top, pretty sure I did everything right. Pulled codes P303 (cylinder 3 misfire) and P141 (O2 Sensor). Spark plug is new. Wire isn't that old maybe 20,000 miles on it. Coil pack worked before I started the job. Before I start buying a bunch of stuff to chase down a couple codes, does anyone have an opinion on this?

 

[Explodr94]

Alright, I think I have determined where I went wrong on this job. First of all it's not a good idea to let something sit for three months and then go back to it.

I have narrowed down my problem to an air leak. I want to make sure I put the gaskets on in the right order maybe somebody could chime in? Assuming lower intake is installed correctly, there is a phenolic spacer that goes between the fuel rail and the lower intake. I installed gaskets on both sides of the spacer, as that is how I remembered it taking them off. Fuel rail goes on top of spacer, then new rubber gaskets on plenum which goes on top of fuel rail.

Is this the correct order?

I used Victor Reinz gaskets on this job, anyone had issues with them?

 

[Abbondanza]

I did the same job recently, after I was getting the misfire codes, as well as the O2 codes (mine are p1131 and p0133)...I hadn't changed the fuel injector o-rings (possible source of vacuum leak?...so I went back and did that which seemed to help the rough idle, and I haven't gotten a misfire code since (two weeks). I still get the O2 and lean codes, though, so I am going to replace the upstream sensor this week (the head gasket failed so maybe all that coolant burning through may have killed the sensor). Also make sure your vacuum lines are all connected correctly with no breaches.

 

[Explodr94]

Thanks, I really appreciate the response. I did replace the injectors, with new ones while doing this job. I remembered looking at the rail and thinking that looks really solid. I started thinking that the plastic plenum may not be completely flat after 16 years and that the torque specs from the Ford Manual doesn't take that into account when tightening down the upper intake. So today I'm going to tighten that down before I go in and redo the o-rings and the gaskets again.

Has anyone else had issues with the plenum becoming warped?

I also checked the spark plug and there was a noticeable difference in the way the engine ran. I tested continuity and the one spark plug that was in there had a resistance of 11.83 and the new one I bought was 5.43. Engine did smooth out a bit, but you can hear the vacuum leak coming from under upper intake.

 

[Explodr94]

Update: Leaking EGR tube gasket was the culprit. Board isn't the same as it was 6 years ago.