4.8 swap questions

[nobox351y]

Forgive my ignorance. Im learning a lot but could use some help.

01 4.8 swap into an 87 suburban stock ecm from that engine. Maf from another. I reworked the harness and I am trying to learn hp tuners to make the truck functional.

All of the wires for the trans, egr, evap, 2nd o2 have been deleted from the harness. I believe I have disabled all of the codes for these circuits.


Engine is running, idles great, but will not come off idle and rev cleanly, until you put it into closed loop with the scan tool. When you put it into closed loop it is driveable, but still shows stft and ltft showing they are adding quite a bit of fuel.

HP Tuners shows all the sensors are working, whether or not they are working correctly could be an issue. STFT show they are adding a lot of fuel at idle.

It is showing codes for some egr, trans, but nothing related to the cam, crank, map, o2 maf, knock, injectors, etc.

Thoughts on how to try and correct this? I really thought this thing would be running, a lot like it should at this point.

[nobox351y]

update: starting, idling is all getting better. Took it down the road this evening and it ran a little better without forcing it to closed loop. It developed a random misfire dtc. I am guessing this is all still related to fueling. So when I get that sorted out the misfire will probably go away.