01 Silv. turbo tune issues... Looking for some ideas where to go next

[gtfoxy]

I am helping a guy tune his 01 Silverado. The truck has had a turbo for over 3yrs now. Originally it was ran up to 15psi on E85. Ran real good for a number of years that way. Now the truck runs 91 pump.

At the end of last year the truck started to become very sluggish and progressively got worse. During this winter the turbo was removed temporarily & the thing would hardly go. Fast forward to now and a fresher motor & a new 70mm turbo & it is still acting up.

It has been throwing 0101 & I have just started helping him work through this but I feel there is something weird going on.

In the logs the cruise shows way rich. The STFT is showing at times up to -30% fuel. The engine hesitates really bad when you first step on it, then cleans out but still runs poorly. The chugging starts at the first stab of the throttle at low vacuum so it is not a "In boost" issue. Replaced the MAF and PCM to no avail. If you run it in OL it runs worse so something is definitely not right.

I am not sure if it is an injector(s) issue or a wiring problem as of yet. It has LS7 injectors @70psi static, 255 inline, other than that it is a stock 5.3. Initially the truck had a WB on it but it was taken off for another project. I am going to loan him an extra one I have laying around so we can get a better idea of what it is actually doing fuel wise.

Perhaps someone can take a peak at the log & tune and see if I am missing something obvious that I am just overlooking.

The first log is before I started messing with it & the second log is where I addressed the 0101 & a few other drivability issues.

[2xLS1]

I didn't look at the tune but the log shows a lot of MAP at 102-103 kPa and still in closed loop with the O2s still switching.

And it baffles me why with all the PIDs you can choose to log why people still datalog so much with the default config.

[POWERZONE]

Your VE table needs to be retuned.

You are running a lot of fuel in your idle and part throttle areas of your VE table.

Retune your VE and MAF tables ASAP.

Looks like you need a 2bar MAP.

[blownbluez06]

my theory: Your MAF might be whacked but still part of your airflow calcs. Why do I say that? Because your airflow values that you're hitting at low RPM are ridiculously high, forcing you to operate in regions that I'm sure you weren't trying to operate in before. Those regions have no timing, therefore your vehicle has NO BALLS!! Try putting some timing in those areas, fail the MAF and work from the VE and see where you end up.

[gtfoxy]

my theory: Your MAF might be whacked but still part of your airflow calcs. Why do I say that? Because your airflow values that you're hitting at low RPM are ridiculously high, forcing you to operate in regions that I'm sure you weren't trying to operate in before. Those regions have no timing, therefore your vehicle has NO BALLS!! Try putting some timing in those areas, fail the MAF and work from the VE and see where you end up.

I noticed the high airflow at the low MAP also. In one map I did try to add some timing in those areas but it didn't help. It does this with any MAF we put in, so it could be a table issue but it doesn't make any sense because the tables were never changed at any point.

At this point I am going to have him swap to stock injectors & start from scratch in trying to diagnose the issue. The Fuel pressure guage intermittently shows low pressure in the 40 psi range & the 02 go crazy rich so I am really leaning toward injector or harness issues.

If you can think of anything else then feel free to chime in.

[gtfoxy]

Also, The MAF was changed after a turbo took a poop & leaked oil in it & wrecked the sensor. The new one is a Part store unit & the other one was out of an 04 5.3. Were the MAF air mass/output frequencies that much different that it would cause this type of running condition?