Lean Condition after initial start up.

[Dave72C]

fun challenge, one I have never seen before. I am not knew to tuning however also not super advanced.

Challenge:
After 32 seconds of initial start up, engine starts to trend into a lean condition to which the STFT will start climbing rapidly, almost like injectors aren't firing (checked fuel pressure, and smoked it for any leaks, nothing)injector data change 12-31.hptSD - 1 injector change.hpl

We currently trying to dial in the VE table, then the MAF to start getting fueling correct, have swapped computers to make sure it wasnt injector circuit, kind of stumped on where to look and map. (I found the after start decay delay, which paints with the 32 seconds) but kind of stuck on where to go from here.

Build: 92 Pick up - 6.0 L99 heads, small truck cam, Open Headers (for now), electronic throttle.

[5FDP]

You can't run o2 sensors with open headers, that will throw all your fuel trim readings off.

Also you didn't set the MAF dtc's to MIL on first error for speed density.

[Dave72C]

Copy that?s why I put open headers in there, I have read where they caused issues, but I?m not sure how to tune around them.

I will adjust the MAF error, I thought it had it error on first MIL, but thanks for the double check.

So what are recommendations for tuning with open headers. Truck is not mine, it?s my fathers I can try and talk to him about completing the exhaust, but he?s a stubborn one.

I do have a wide band, but was trying to use the narrow bands to get idle fueling correct.

[5FDP]

The recommendations is that you/he completes the exhaust, you straight up can not tune with o2 sensors on open headers.

o2 sensor stands for oxygen sensor, open headers means LOTS of extra oxygen that will skew all your data. You can't even use a wideband with open headers except for WOT tuning. Idle and any part throttle tuning will suck in extra oxygen on open headers.

[Dave72C]

Copy, we will make sure we starting getting exhaust buttoned up, I?ll probably throw an extra 02 bong for wide band easy in and out. Everything you said makes sense, my fathers a mechanic so he was arguing with me a little when I notated the problem, but wanted to get a second opinion. Thank you!