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

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[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.

:nixweiss:

[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. :confused:

[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...

[slows10]

There seems to be no table to get it in open loop. I had the same thing on my 1998 S10 with the 2.2 4cylinder. It had a table to turn long term trims off by maxing out the temp table. But it would still use the short term trims and the o2 sensor would still operate correctly. So I unplugged the o2 sensor and then it went open loop. Try unplugging the o2 sensors.

[Extinct]

I thought about that, I was hoping I could keep the 02 sensors just as a data input.

[Extinct]

Well disconnecting the O2 sensors did the trick with respect to putting it in open loop - hard to believe that is the only way to do it.... Still doesn't answer why the O2's where cycling around a 14.0 switch point instead of a 14.7, I've never seen a failure of that type. Usually they work, or they don't work, weird...

[hog]

[QUOTE=Extinct;199631]Well disconnecting the O2 sensors did the trick with respect to putting it in open loop - hard to believe that is the only way to do it.... QUOTE]
that must be an EFILive things as Tunercats 2 has the Open Loop LCosed Loop fueling as a switch.

If you really want full control of the L31, a 0411 PCM swap and 2001-2002 L31 Vortec 350 Express Van calibration. Get a hold of Lextech for the retrofit pinout tables.



peace
Hog

[joecar]

Well disconnecting the O2 sensors did the trick with respect to putting it in open loop - hard to believe that is the only way to do it.... Still doesn't answer why the O2's where cycling around a 14.0 switch point instead of a 14.7, I've never seen a failure of that type. Usually they work, or they don't work, weird...Hmmm... weird... what fuel is being run...?


Like Hog said, a 0411 swap will give you a multitude of tuning parameters (not to mention OS's).

[Extinct]

I know all about the 411 swap, I wasn't interested in doing that much work. Truck is running regular fuel. You know, after looking at the Tune file parameters for several days it's clear EFILive just sort of did the bare minimum on getting parameters for this ECM. There isn't a single temperature compensation parameter available, yet I know they have to exist, hell even my MEFI on my boat has those and it's an old aldl stream. Really disappointing, especially considering the shear number of these vehicles on the road...

[turbo]

Did you reset the fuel trims with the scan tool

[Extinct]

Well just as slows10 stated, there are no fuel trims once the O2's were disconnected. I did reset them with the scan tool while they were active, but the problem there is the PCM would not go as lean as I wanted so I was left with no choice but to disconnect.

The L31 pcm should really not even be considered "supported" as the tables provided barely give any functional control with respect to modifying the tune, at a minimum I don't think EFILive should charge customers for a VIN license because the ability to do anything is so minimal.

However, I will say I am glad that there is some support, because the alternative is no support because to my knowledge no one else provides L31 support. I can probably live with what I have here because the truck is stock, but for anyone reading this thread in the future my recommendation would be to not try to do anything with respect to serious modifications without doing the 411 pcm swap.

[turbo]

Sorry fella I've never had anything to do with at PCM, and I'm on my phone ATM so can't read your tune. I'm sure there will be plenty of people on here that can help you. But you have got me interested now so I will have to look at the tune and see if I can help you in any way 👍

[joecar]

Fuel: is it plain gasoline (E00) or is it E10 or E85...?

[turbo]

ive changed the tune a little bit for you fella, i did not find the settings that i would have liked too, as you say its very limited as too what you can do with it.
i would like you too give it a go though.

Main thing i seen was that it was not set right for SD mode (P0101) (P0102) (P0103).

[EagleMark]

I know all about the 411 swap, I wasn't interested in doing that much work. Truck is running regular fuel. You know, after looking at the Tune file parameters for several days it's clear EFILive just sort of did the bare minimum on getting parameters for this ECM. There isn't a single temperature compensation parameter available, yet I know they have to exist, hell even my MEFI on my boat has those and it's an old aldl stream. Really disappointing, especially considering the shear number of these vehicles on the road...Your right! Sort of... there is not even bare minimum of parameters to do a tune even on a stock motor. I tried very hard to make some of the tutorials work with the 98-00 Vortec PCM as well. The only reason I got as far as I did was because I also have TunerCat OBDII, which has most of the simple missing parameters needed to do a basic tune.

There is a dissasembly publicly available for this PCM so things could be added via a CAX file. But after weeks of work to get some of the Auto Tune, VE etc... tutorials to work and even handing the hex locations needed to EFI Live on a silver platter, they were not interested in updating this PCM to a point of acceptable of the EFI Live reputation and workable for a tune. Seriously I had over 100 hours into this project when I first got EFI Live! Should have got a great reception and I still don't understand why there was absolutely no support or interest! So I gave up and did the 0411 swap on my truck and usually run my RoadRunner just so I can constantly play and learn.

Worst part about that is I've had more 96 to 2000 Vortec work in the last year because of TunerCat OBDII software, way more then all other OBDII vehicles combined.. If EFI Live worked with the Vortec like how well it does with LS1 b and others? It would be much easier to only have to run one software...

Part of your issue may also be using the EFI Live Scan tool for Commanded AFR. It is wrong! You have to use PID GM.AFR_B which is for a LS2 engine. But if you use Scan XL Pro the proper PID GM.AFR does work. If I remember properly there was also no way to fail MAF and be able to turn off transmission DTCs at that time. So running SD tune tutorial was also out of the question.

Just give up! I think the only reason the 98-00 Vortec is listed is to keep score with competition? Even if it were a free license it would not be worth using. Can't even do a full flash on these PCM if you want to change OS for segment swaps.

I'd like to end that bash there though because EFI Live, this forum and especially joecar is far superior to any other tuning tools!

[Extinct]

OK, so I am back on this now after doing some tuning. BEN factor seems way off, so I grabbed some data. GM.AFR_B does not work at all, but GM.AFR seems to have some sort of correlation although the units are apparently way off (WTF?). I think I could use that if I could get the units in range as it seems to have a pretty good correlation just eyeballing the graph - but why are the units off? Also, I tried to modify the BEN factor by multipling the GM.AFR by 97 (target AFR divided by GM.AFR for one range of data I was confident in), but for some reason did not load the modified calc.pids.txt (located in C:\Program Files (x86)\EFILive\V7.5\Installation Defaults\User Configuration) -anyone have any idea why that is?

Attached is the last log file I ran for reference.

16248

[joecar]

calc_pids.txt should be in My Documents\EFILive\V7.5\User Configuration.

[Extinct]

calc_pids.txt should be in My Documents\EFILive\V7.5\User Configuration.
Thanks, that helps.

[Extinct]

Well this is just bizarre. Went out today, made sure the backup VE table and primary VE table were the same (in the columns where they matched), and still almost no change or if anything it went the other direction. I am trying to lean out the mixture, but modifying the VE table seems to have no effect. The MAF and O2 sensors are disconnected, so I know that can't be influencing the PCM (data confirms as well), the IAT, ECT, and TPS seem to be working fine, so why won't this thing lean out???? I've got as much airflow in the VE table at 30kpa as I do at 85 - but it still runs fat! What the helll?

I would welcome any insight anyone could give (tune and log attached).

Thanks

Tim

[joecar]

Are you getting a MAF DTC...? If not, then the PCM is still trying to use the MAF table (even with MAF disconnected).

[Extinct]

Are you getting a MAF DTC...? If not, then the PCM is still trying to use the MAF table (even with MAF disconnected).
I have the MAF sensor MIL turned off, so no MIL indicator. Looking at the log file there is not DTC so I guess it isn't looking for it anymore.

[Taz]

I do not know the workings of the Blackbox Vortec PCM very well ... you may have to fail both the MAF & the O2s to get it to run off the Backup VE table.

Try the attached tune ... it should cause the PCM to fail the MAF and the O2s ... rather than perhaps just moving on to some unknown mode.

After you flash this tune, then try adjusting the Backup VE table to see if there is any change - unlike the current strange situation.

[Extinct]

Quick update - screen shot showing data from yesterday. Very strange that the VE tables don't seem to affect anything in idle or low load conditions - however I did do a test on a later log where I hit WOT - instantly went to the target AFR of 12.8. I am not sure what is driving the variation in AFR as the VE tables cannot be this far off (bone stock Tahoe except for shorty headers).

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