Help! Strange Problem - Modified tune - no change in engine

[Extinct]

OK, humbly asking for some help here with a weird problem, I'm sure I am probably overlooking something but I can't tell what.

To start with, I am not an EFILive newb. Have tuned my LS1 very successfully, running COS, also tuned my Duramax. So this is not my first rodeo.

Now to the problem. My sons Tahoe was getting 7 mpg. Took a look at the fuel trims and o2 sensors - one was a little lazy. Since the truck was stock except for headers I decided to say screw it and just convert to SD and then tune for some lean cruise - mileage problem fixed.

OK, long story short, no matter what I do, the AFR is stuck right around 14.0 as verified by the LM1. LTFT's are +20percent, but still runs 14.0 no matter what?

I have tried multiple successive changes, including:

1. Modified Stoich
2. Modified injector flow rate (did not actually modify injectors)
3. Modified VE tables

Of course, I unplugged the MAF and turned off CAT protection. Also modified PE enrichment based on modified stoich - BTW, also runs about 14.0 in PE mode.

What am I missing? Seems no matter what I do the computer maintains about 14.0?

On a related question, why are the O2 sensors cycling when the truck is running 14.0 - they should be way out of range by that point?

Attached is a recent log file and the most recent (maximum changes) tun that has no effect on the trucks running.

Screenshot of relevant portion of log file below.

Any help would be greatly appreciated.

Thanks

Tim

Log_0004.efiLog_0004.efiTahoe.tun

[wait4me]

The computer is using the backup Ve table is why you are not seeing a change.

Also, if you are trying to run open loop, then you should set it up to run open loop, also, you should not be seeing ltrims or strims if you are open loop.

My guess is you have a vacuum leak, or a bad o2 sensor, and it needs to be fixed. Why hide a problem.

[Extinct]

The computer is using the backup Ve table is why you are not seeing a change.

Also, if you are trying to run open loop, then you should set it up to run open loop, also, you should not be seeing ltrims or strims if you are open loop.

My guess is you have a vacuum leak, or a bad o2 sensor, and it needs to be fixed. Why hide a problem.

Jesse, thanks for the reply. I thought the computer might be using the backup VE table as well, so I modified the backup VE table (I did it in a different tune, tried that tune also) - no change. I do want it to run open loop, but on the L31 calibration I can't find any setting that tells it to go in to open loop - there is no "enable open loop above x temperature" table that I can find - am I missing it?

I've disconnected the MAF, changed the fault frequency so it is always faulted, so why is it still running off the 02's and using LTtrims and STtrims?

It does have a lazy O2, but since I decided to run open loop so I could lean it out, I decided not to fix the O2 since I wouldn't use it anyway (would always either be lean or rich if it was in PE - never at stoich).

As always, any suggestions are much appreciated!

[slows10]

B3601 is set to 16:1 ?? EDIT, sorry I just saw you purposely set it to that.

[slows10]

Is B1044 set wrong?

[Extinct]

Yep, trying anything to get this thing to lean out. In open loop it should use that value to calculate base pulse width for the injectors, but apparently it is not. I think Wait4me is right, it isn't in open loop yet, but I can't figure out why? If you look at the log file it shows it is targeting 16:1 for AFR but obviously not even close. Average O2 sensor readings are 527mv and 513 mv, which is normal if you are running closed loop. Open loop and lean it should be bottomed out.

[Extinct]

I set B1044 that high to make sure it wasn't in PE mode somehow. If I can ever get normal operation correct I will adjust B1044 to a reasonable value.

[Extinct]

Thanks for the replies guys, I definitely believe more heads are better than one, and I damn sure haven't been able to figure it out.

[slows10]

Are you getting a maf dtc?

[Extinct]

No, which is a little bizarre given the MAF is disconnected. I do have the MIL disabled for the MAF, but did not touch the DTC enabler. I will add the MAF to the PID's and log it on the way home - not sure how it coudl read anything disconnected though...