Wild behavior on 4.8 swap

[jmenge209]

I've tried to read until my eyes are bleeding, but it seems the more I do the more I confuse myself. A little background, helping a disabled friend complete a project he started years ago and is now unable to complete on his own.
-4.8
-2001 P01 PCM
-MAF AF10043 (from a 2005 1500)
-Injectors 25320288
-Returnless fuel rail
-Drive by cable throttlebody
-3.8 bar fuel pressure regulator in the tank
-PCM not controlling trans (non computer controller auto)

See attached log file. The first few minutes are with MAF disconnected (runs rich and hangs around 2-2.4k RPM), with MAF connected it hunts for idle and runs extremely lean (according to scan data). The base tune is from a 2001 truck 4.8 file with VATS removed and the flow rate vs KPA adjusted.

Would appreciate any help or direction

[SiriusC1024]

Cam?

[jmenge209]

No sir, no cam. Motor is completely stock other than the fuel rail being run as returnless and a different MAF

[SiriusC1024]

Did you unplug the MAF so you could tune SD? If you want it to run SD with the MAF unplugged, you need to set Engine Diag>Airflow>MAF Frequency Fail High to 0Hz and >DTC>P0101, P0102, P0103 to MIL on First Error. Go to Trans Diag and disable P0101-P0103 max line pressure DTC's.

[jmenge209]

I unplugged the MAF as a quick check to see if it helped the idle as with it initially plugged in the car would barely run, stumbled, misfires, etc. Unplugged it, the idle shot up to nearly 2k... then once it had some heat in the engine I plugged MAF back in to record some data before shutting it down.

Point taken about disable MAF when I get to speed density tuning. I feel like there's something substantially wrong I need to address before beginning that step next. What I'm curious about is why the dynamic airflow is so substantially different than the desired idle airflow. Also, do I need to 0 out all the P/N cells under RAF and adaptive areas? Thank you!

[SiriusC1024]

If it's a stock engine then there shouldn't be this much trouble with a stock tune. The only difference is the MAF and injectors. Might try true SD and see if it clears up.

[jmenge209]

I'll try that next. Just baffled how far off the tune was with/without MAF plugged in (rich without the MAF crazy lean with it plugged in)

[2xLS1]

All the V8 truck MAFs from 99-07 classic are the same.

[jmenge209]

That helps, one less variable to track down, thank you!

[ns158sl]

Remember the MAF has the IAT sensor.

[RDF1]

Have you checked the fuel pressure?

[jmenge209]

Fuel pressure is regulated by the in-tank pump in the vehicle. It is set at ~53psi

[SiriusC1024]

High idle and running lean. Is everything sealed up? There's an EVAP code.

How's the log look in SD with the MAF still plugged in?

[jmenge209]

I'm wondering if there is a mechanical issue as well... It does seem to pull decent vacuum numbers, but the evap line is hooked up to the vehicles existing system. I think I'll cap that off temporarily to see how it affects things. Also, I just noticed in the log file IAC is never commanded anything other than 0? Seems odd right? Could also be a misfire driving up the AFR I believe.

I'll log with a wideband in SD mode when I can get back to the vehicle. Just wanted a better starting point with the tune so I don't waste too much time when I'm at his place.