Exhaust leaks pull air into the exhaust at idle and cruise - if you have leaks, that may well be your problem! Did you tune it in open loop using the wideband first? Did you do any further tuning after that using the narrow bands (STFTs or LTFTs)?

Also, for the calculated PID part of it - if you have incorrect injector flowrate numbers in your tune, you will not get a correct reading using that PID - GMCtrk, I think you will find your hand caculated MPG is not as bad as what you are seeing in that PID.

One more thing to consider with big injectors - there is a minimum pulsewidth table in the tune that most people don't know about. It causes the injectors to hard stop above the pulsewidth required for clean idle AFRs. Reducing the VE won't lean it out no matter how much you cut it down... If you are using EFILive, I can tell you how to get to it - for HPTuners, I don't know if they have it available. I kind of doubt that is the problem here though...

 

Ferocity02 - can you post your tune up?

 

Are you talking about the small pulse threshold? Mine is set to 2.5ms per the injector data from FIC. At cruise I'm around 3.2ms and idle around 2.1ms. In the tune, both the Minimum Injector Pulse Width and Default Minimum Pulse Width tables are 0.125ms at every RPM, and 0ms at 0RPM. I attached the injector data I'm using.

If the pulse width can't get small enough wouldn't that register with the NBO2's are as rich?

I'm still working on the base tune my tuner sent me. There has been zero "dialing in" of the tune, except for the changes I made for the injectors.

 

I'm talking about B9021 - you can't even see it unless you install a cax file into EFILive. It causes a hard stop on the minimum pulsewidth and if you are reaching it, nothing will lean it out below that value. It will show on the narrowbands and wideband as rich idle - yours is pulling fuel at idle, indicating it is rich. I didn't see your wideband reading on your log, so couldn't see what it is showing at idle.

The zip file above doesn't work...

 

So, I just installed the cax file for your truck's stock OS, and the minimum pulsewidth in B9021 is 0.896682 ms - so, as long as you are still running OS 12208322 - and unless your pulsewidth gets down that low, you aren't limited. Seems that your particular OS is much lower than most I've seen (cars). Many of the cars are limited when you install 60# or bigger injectors and you can't get them to idle correctly no matter how you try to lean them out (unless you know about this table)...

 

It still runs at stoich at idle according to be NBO2's, so perhaps I'm not hitting the minimum yet. In my log the lowest pulse width is 1.068ms. I'm running a 12212156 OS so perhaps the B9021 is different.

I found an exhaust leak where the crossover meets the log manifold, so I fixed that. And I replaced the gasket between the crossover and the driverside manifold. It wasn't leaking but I replaced with with an actual gasket instead of the o-ring. There was no change in the logged MPG, fuel trims are the same.

Also checked for vacuum leaks using EFILive. I logged STFT, LTFT, and O2's while using first propane and then brake cleaner around the intake gaskets. No leaks were found.

One weird thing I noticed is how the LTFT's are the same or very close when cruising, but when coasting or off the throttle the bank 2 LTFT is much lower than bank 1, and they get as low at -15%. Could this be because the bank 2 sensor is reading a combination of bank 1 and 2?

Also the calc pid is saying I get better gas mileage coasting in neutral than in DFCO. Whereas before the gas mileage in DFCO was off the charts (probably not as accurate in DFCO). Very peculiar.

 

LTFT at -15% tells me that your tune is quite a ways off. 15% too rich, on average....

 

Agreed. Still on the base tune though, much dialing in to be done once the new wideband and injectors arrive.

 

With your exhaust leaks, questionable injectors, questionable wideband, and only a base tune, this thread is kind of silly. Putting the cart in front of the horse, so to speak.

Straighten out the truck, get it tuned, and it will all come together for you.

 

I would agree - get everything straight, get a good wideband in it, put it in open loop and tune it... then see what it is doing as far as mpg... Not sure how much boost you plan to run, but if it were mine, I would go to a COS and 2Bar...