Just finished swapping head gaskets on my '03 and had no major issues starting up. White smoke out the tail pipe for a couple hours but nothing unexpected. Took the truck over to get the SES codes read, expecting just some o2 sensor nonsense, got these:

P0300 Random Misfire Detected
P0102 Mass Air Flow Circuit Low Input
P1590 Rought road signal implausible Drive cycle A: Signal implausible
P0154 O2 Circuit No Activity Detected (Bank 2, Sensor 1)
P0305 Cylinder 5 Misfire Detected
P0307 Cylinder 7 Misfire Detected
P1884 CAN message WFPDK (DKI) invalid (FFh)

When I first started her back up after replacing the HG, I figured there would be some misfires and a rough initial start. And it was pretty rough but she got going and I pretty much immediately drove across the state of FL for about 3 hours. No overheat, no noticeable issues. Surprisingly good mileage. For more insight, when starting it cold, idles a little rough but settles down to a nice grumble after a good 10 seconds or so.

With these codes, I'm thinking that hopefully its just an issue with MAF and O2 sensors that are causing the misfires. The plastic air inlet passageway is a bit cracked and held together with some duct tape so theres a flag. What are all yalls thoughts? I'm about to get the truck registered and dont care to drop $300 if the liner could be slipped or engine cracked.

 

Oh and additionally, I had replaced the spark plugs/wires. Bosch Plugs and Duralast 7mm wires. In hindsight I shouldve gone NGK, really not sure what I was thinking

 

Sounds very similar to mine after doing my gaskets. I ended up replacing the rear O2s, the MAF (use genuine Bosch only), the coils, wires, and plugs, and the purge valve (Dorman 911-800).
I still have the "rough road signal implausible" code but that doesn't trigger the CEL.

 

You had the misfires too? Im just worried because the misfiring cylinders sit next to eachother

 

Not sure if you had existing codes before your head gasket. For the time being, clean your MAF and check the connections. 1884 I guess is related to MAF connection etc. Sometimes after driving for 3 hours, some codes might have disappeared. Better check what codes are left. When I did my HG, all misfire codes showed up and was rough but after driving for a while theyre gone, I guess from all the solvents and cleaner inside fouled it.

 

I'll look at the maf sensor and try cleaning the connections. Meanwhile, just opened up the expansion tank after letting it sit overnight. The tank was pressurized... fluid rose about 1/2 inch. Immediately I tried smelling the air that escaped and I could be imagining it but it smelled a bit like gas.

Needless to say, I'll try running a CL test later today. These clues seem pretty clear to me, and it doesn't look good. Anyone got some more positive alternatives here? Lol

 

I did start having misfire codes and a flashing CEL after I did the HGs. I don't recall the positioning of the misfires, sorry.

 

Thanks. I hope mine is that simple, hard to look past the smell in the coolant tank though

 

If it persists, it might be the case that your head gasket isn't sealing or one of your bolts isn't torqued properly, or has been over-torqued and has stripped out the threads in the block.

 

I did follow the torquing procedures for the head bolts, but making that final 90 degree turn was a little tough especially without an angle reading torque wrench. So unless the heads are actually that sensitive to the bolt torques, I'm doubtful that could be it.

Furthermore, I couldnt help but notice that as I installed the LH head back onto the block, I nicked the head on the back alignment pin just a bit. So that would be in between cylinders 5 and 7. Suspicious I know....

If I have to take apart the heads again, a week after finishing a HG job, I swear I'm gonna shoot myself