Speed Density Fuel Trim Help

[StevenArgo]

I have been searching/ reading/ watching videos for weeks and I cannot figure out what is going on.

I have a LQ4 out of a 2003 Silverado 3500. I have been fighting running issues and found 4 bad injectors. The engine, trans, computer and harness was already removed before I bought it. I am still attempting to get this thing running half decent and I plan on running speed density tune due to this being installed in an off-road only vehicle. What is currently done is a head swap to 706 heads from 317s. I did this to bump up the compression, I need more low RPM torque than high RPM HP. BTR mls head gaskets and head studs. I bought a set of the AC Delco 50lb/hr injectors to replace the old ones for future upgrades (12613412).

I have failed the MAF as guided by Goat Rope Garages videos attempting to dial in the VE table, but regardless of what I do, the data scanner keeps showing it to be extremely lean. I have went up with enough fuel that it will barely run if I can get it started.

I do not have a wideband O2 sensor, I looked into getting one but with the MPVI2 that I have, I'm looking at spending $250 for the pro features + $230 for the wideband. Its not financially doable at this time.

I have searched and found the injector data and added it to the tune for the 12613412 injectors. I'm not sure what I am doing wrong or what is going on, any help is greatly appreciated.

6.0 LS Cherokee XJ STOCK -VATS Removed- VE tune prep.hptLog# 6.hpl

[2xLS1]

I can't look at your log file but are you running open headers or any find of open exhaust close to the narrow band O2 sensors?

[gametech]

Sounds like time to check fuel pressure.

[edcmat-l1]

The tune file posted the VE is basically stock. Looks like it may have been raised slightly over stock but nothing extreme.

And you don't tune one of these by sitting still whacking the throttle repeatedly to 5000 RPM. You need to drive it. Needs to be under some load.

And you need to have a fuel pressure gauge on it that you can read while driving. And you need to have some exhaust length behind the O2 sensors. Preferably a few feet with at least one bend in the pipe somewhere.

[Alvin]

The injector data you used differs from what I have. The same injector PN can have different data in different OEM tunes so this is a absolute problem but it might hint at one.

Where did you get the data?

The entire thing is very lean. I'd double check fuel pressure as first step.

There are no exhaust leaks? That will make the o2 sensors read lean. Along with the sensors mounted too close to the tail pipe/exhaust dump.

[StevenArgo]

I have full exhaust (2?" into a Y pipe and a 3" pipe to the back, no exhaust leaks. New Denso O2 sensors about 4-6" from the shorty headers. I have a fuel pressure sensor installed and it stays between 51-52psi at idle to a little over 61psi under load. I have driven it to see if the numbers would change and added fuel in 10% increments in the VE table until it was nearly doubled from stock, still showed to be lean if I could get it to start. I put the VE table back to stock because it runs better but it's still not right. I was whacking the throttle in that log file while messing with the tune to see if it would respond differently or not show being super lean before I drove it again, im not wanting to risk damaging my engine.

[bk2life]

I have failed the MAF as guided by Goat Rope

this is your first issue.

nothing agains mr goat, but his way of tuning isnt my cup of tea.

under 4k rpms use your stock O2 sensors. WOT and above 4k use the wideband.

ID put your stock tune in, fail the MAF and start tuning your VE first. Then MAF, then idle.
from there you can up timing, and Ve for performance, but, get it runnign right before you worry about performance.

do you know how to correclty fail the MAF?

[StevenArgo]

I basically have the stock tune in it with the MAF failed (I think), with the exception of injector data for the 50lb/he injectors. I got the data from a gen 3 tune file someone posted on this forum wanting the injector data for the gen 3 stuff. It was on a '02 Yukon I think. I copied the data to my tune file. Im trying to get it running right but regardless of what I do to the VE table, I keep getting super lean readings.

[bk2life]

I keep getting super lean readings.

please post your most current tune and log files.
I'll look at your settings once you do.

[StevenArgo]

Log# 6.hpl 6.0 LS Cherokee XJ STOCK -VATS Removed- VE tune prep.hpt

[StevenArgo]

*Update* I was able to locate and borrow an AEM wideband from a friend. it is also staying hard lean, showing 22.4? afr. Im not sure what is going on with this thing but its definately very lean.

[StevenArgo]

For some reason HP Tuners automatically blocked my IP Address temporarily, I don't Know why. I went to the junk yard and pulled a few used computers and plugged them up, it seems to run fine.. I have been fighting 2 different, bad pcm's. I will license one of these and start over.

[bk2life]

I have been fighting 2 different, bad pcm's. .

very rarely does a 'pcm' go bad