5.0 Quarantine Tuneup.

[TekMan05]

not starter fluid but soapy water looking for bubbles and listening to the engine. I drove it today and honestly felt fine. Didn't check the scan tool though still seems like there is a slight power bluff or maybe the computer is still adjusting? I wouldnt think smoothing the intake runners would affect that, as I only did minor smoothing. I might try to reach out to a tuner and see if they're willing to read some logs to see if it's a mechanical issue or maybe a tune revision is in order.

 

[TekMan05]

 

[410Fortune]

The truck should start and idle normally, not “high and then settle down”

Smoothing intake runners should not cause flow issues the computer cannot recognize, these pcms can account for many changes without you noticing a problem with the way it runs and drives or setting a code, even headers and a cam will not cause the pcm to require a tune in order to run properly.

The lean codes are either an air leak that effects both banks (un metered air) or a low fuel pressure / injector issue that effects both banks

Did you change the valve springs to go along with that e cam? Stock springs will not work

 

[Blk2kXLT]

My codes went away when I swapped back to the stock intake. The MAC aftermarket intake adapter has the laminar flow screen of the MAF removed. I am guessing that air is bypassing the sensor. Can you try that? Partial throttle readings just like you are showing. Not seen when hot out but that's CA hot. Nearly the same truck 2000 XLT, MAC with TM headers. Had that P171 and P174 forever and a day.

Other things if not above:
Anaerobic gasket maker used between the lower and upper manifolds on reinstall?
Fuel pump since sock could be clogged? Fuel filter?

Also a warning with TM headers is that without careful zip tie routing of wires away from pipes and external "anti heat sock" shielding around the wire to spark plug attach points the wires can melt. I have melted two so far but the misfire is super easy to detect. Kept a second set of wires in my trunk for this reason.