Tunning 2000 Vortec 5.7 350 cant figure out what I am doing wrong - No Wide Band --

[LunaAZtech]

This is my first tune... Trying to learn the terminology, the interface, specially the scanner and how to get errors from there and use them to correct the actual program. I am aware and understand that a Wide Band reading would help me tune a lot better and accurately. I would like to learn without one for now, considering that I am only tuning for a K&N cold air Intake and a Flowmaster.

I have been changing the Primary VE table up and down based on the Short Term fuel trim. I simply copy paste add half percent. I have made a couple other changes but don't remember exactly. A few other changes I made, I reverted on because it made the truck run like doo doo and stall.

I think I have the wrong rinse repeat process or using the wrong error table calculation, I'm doing something wrong because I keep changing it and it stays running lean on the ST and LT. At times it has gone to very rich. I don't remember what I did so I just reverted because it felt wrong. At any rate...

This has to be easier that what it seems to be.
Can some one please help give me some basic steps to tune so I can get the most benefit of the CAI and improved flow on exhaust? I would much appreciate some help. I attached the scan logs and the tune file ive been working on.
How do I turn off the rear O2 on both banks, and do I do this after the VE is good?
how do I remove the rev Limiter and Speed Limiter ?
There is a Primary and Secondary VE table, what's the difference and should they be the same?

[5FDP]

The computer uses the MAF and VE together. So if you try to tune the VE with the MAF still working, you are not doing correctly. They must be done separate from each other. One log has the MAF working and the other doesn't. The modded file doesn't have the MAF failed.

This computer will use the secondary VE table when in speed density. The data has to changed there and then copied over into the primary VE table. As you can see the secondary VE has less resolution to the table than the primary so you have to copy over the matching data rows and interpolate the to create the rest of the table for the primary and the smooth it. The primary table is used when the MAF is not failed.

You need to slow down and read how the power enrichment EQ ratio works as well. Do the math here, you have 1.487 as the highest value in that table. So 14.70/1.487 = 9.88 AFR commanded at WOT. That is insanely rich and will have terrible performance, could even foul spark plugs.

Speed limiter is in the speedo tab. Rev limiter setting is in the cutoff/DFCO tab. If you don't have the valve train or camshaft to support a higher limiter, going to 5,800-6,000rpm isn't really helping you.

[LunaAZtech]

Ok I got that part... MAF and VE has to be done separate.
VE has to be done with MAF failed.... How do I fail MAF properly?
To tune for VE do I just keep adding the Short Trim to VE?
Once the VE is done how do I Turn off VE to Tune for MAF?
What error calculation do I use in the scanner to figure out the error in MAF?

I have no idea how Power Enrichment EQ ratio works... can you point me to an article and how that works.... what would proper values here look like if what I have is improper?
If you say that I am running very rich, why am I getting lean readings in my short trim?
Don't I not want to dump extra fuel in for now and figure out the VE and MAF first ? That's what I read somewhere.

the Rev limiter was a question just for reference. I do realize that going to higher revs without the power at that level is useless. I don't see a "cutoff/DFCO tab"

I apologize for all the questions but I do appreciate your help.

[5FDP]

Ideally to fail the MAF you have to go into the engine diag tab and set the MAF fail hz to 0hz, then set all 3 MAF dtc's to MIL on first error to trip speed density.

I use a wideband for tuning MAF/VE so I don't have the fuel trim error graph thing down. There might be a write up floating around in the VCM scanner how to's.

Once both VE's are done you can enable the MAF again. I forget off hand how to put the vortec computers into a MAF only type mode.

Always read what the tables does when you drag the mouse over a table. It will display a message about the table at the bottom of the tab telling you what it does and sometimes how it works. Look at your stock file, see how fueling is conservative when you do the EQ ratio math. Factory calibrations are generally rich around peak torque and lean out a little at peak horsepower.

Generally speaking a NA engine build makes good power around 12.0-12.5. The way you had your PE in that modded file was drowning it in fuel. Fuel trims do not work at full throttle, power enrichment goes into open loop and this is why a wideband would be required for tuning full throttle. The intake and muffler you changed adder basically zero power so changing the PE as of right now is something you need to do.


Your short term trims being rich outside of PE is different. Closed loop control will try to achieve the stoich setting in the calibration and that is what the fuel trims are trying to get back too.

The cutoff/DFCO tab is in the Fuel tab. If you can't see that you are in basic view. Change to advanced view under the edit tab.

[LunaAZtech]

OK … Found the cutoff/DFCO

The Maf frequency I have to set is both the Fail High.... and I guess setting fail low to zero also wouldn't hurt either. Correct?
I've heard of just disconnecting the MAF would put it into VE tuning is that proper, although it may be a way to do it?

Wide band, I will do eventually just want to get my feet wet with tuning on Narrow band. I searched and found some write ups that help with tuning on narrow band but I believe they are out dated for the version of the software that I am using not sure... Maybe you can help point me to one.

I will focus on getting VE on the right track first then figure how to put the ECU in MAF only later.

Thank you for your info on the Naturally Aspirated 12.00-12.5 … I might be still a bit on the rich side but not as bad as before...
1.20751953125 1.211181640625 1.21337890625 1.216552734375 1.22607421875 1.23876953125 1.25 1.257568359375 1.262451171875 1.263671875 1.263671875 1.255615234375 1.233642578125 1.21533203125 1.2080078125 1.203857421875 1.199951171875

I copied and pasted so you could take a quick look at the numbers. Now I understand a little bit more that the numbers that I show are actually trying to lean out the richness that I am running at PE... the computer is trying to fix my screwup.... is that correct?

I really do appreciate the time you are taking in helping me with this... Eventually I plan on taking some sort of online course where I can better understand some of these concepts and the tool much better.

Thank you thank you thank you for your time.

[5FDP]

I copied and pasted so you could take a quick look at the numbers. Now I understand a little bit more that the numbers that I show are actually trying to lean out the richness that I am running at PE... the computer is trying to fix my screwup.... is that correct?

I'm not sure what you mean by this.

Regular driving and power enrichment are two different parts of the calibration, which I think you understand. PE is only enabled when requested based on the PE settings. The target AFR is suppose to get richer than stoich and this AFR does not translate over into regular everyday driving when you're just cruising around.

It's going to asking for stoich (14.7 afr) everywhere but in PE. With narrowband sensors you can only calibrate the MAF/VE with the fuel trims in closed loop.

[LunaAZtech]

Ok I understand.
I copy pasted the PE Curve I had in EQ... just showing you hat I had lowered it. Didn't realize it would copy all the decimals.

NOW... I figured out, thanks to you how to set it to closed loop for VE disabling the MAF... also set all other parameters to stock and just focused on the VE table.
I think I did much better almost all numbers are on the slightly rich side. Right where I want them for the most part. I just have to take it out of MAF … and move on to MAF tune...

[LunaAZtech]

Is this correct? Can anyone here confirm or deny or add best - better practices to this procedure.

1.. Set the Dynamic Airflow High RPM Disable to ZERO. HPT > Engine > Airflow > Dynamic Airflow > Hi RPM Disable. This will throw your tune into a MAF only tune and ignore the Ve Table for fueling calculations.

2. Disable DFCO by setting DFCO enable temp to 284*. HPT > Engine > Fuel Control > Fuel Cutoff > Deceleration Fuel Cut-off > Enable Temperature.

3. Disable COT HPT > Engine > Fuel Control > COT Lean Cruise > COT to DISABLE.

4. Disable LTFT by setting the LTFT minimum Enable ECT to 284*. HPT > Engine > Fuel Control > OL&CL > LTFT Enable > Min ECT.

5. Copy your Hi Octane timing table to your Lo Octane timing table.

Save this tune with the changes above as MAF-1 or something OTHER THAN your current tune. Do not overwrite your current saved tune! - very important as you will want to cut and paste the tuned MAF table back into this tune once all is done. Now flash (write calibration only) this tune (MAF-1) to your truck.

Set up your VCM Scanner:

You can use this configuration posted in the HPT configuration repository or you can build your own. I actually used the one posted in the HPT forum and modified some of the histograms to my desires. For this logging session, use histogram #4 (tell you why later).

MAF tuning LTFT.cfg
Unavailable

Start your truck and get your O2 sensors hot. Using the VCM controls in the scanner, reset your fuel trims! I always do this out of habit and for good reason as if you have any stored LTFT’s, they will impact the final calibration.

Start logging while looking at histogram 4 in the COUNT mode. So by that, click on the big capital C in the toolbar (next to the “L”). The goal will be to obtain 150 counts in each cell (typical range you will see hits will be from 3000 - 8000 Hz). Now, drive normally with nice slow acceleration . To hit some of the higher cells, put the truck in 2nd gear. For the higher cells, you may notice that the logging suddenly stops. This is because there is a filter built into this histogram to filter out any Pe numbers. This is very handy as all you need to do is just drive smoothly and obtain whatever cells you can. Once you have at least 150 hits in the cells you can hit, stop the log and “save data as”. I usually save this as MAF-1.

Now that the data is saved, click on the “A” which will now display the average for each cell. The numbers you see here are the “percent” off from your commanded STOICH value in your tune (usually 14.68x for gasoline), either rich (negative values) or lean (positive values). Highlight the entire table in histogram 4, ensuring that you are in “Average” display and right click, copy. Open your MAF-1 working tune (the one you flashed to do this log) and go to Engine > Airflow > General Airflow > MAF Calibration, Airflow vs. Frequency and highlight the entire table. Now right click on the table, select Paste Special, multiply by % - half. What this just did was correct your MAF calibration by 50% of the values you just scanned. Personally, I click on the smooth selection button one time here, save the tune and reflash into the truck. Repeat the logging process with the cut / past special multiply by % half into the MAF working tune until all of the cells you are logging are within +/-0.75% of zero or tighter. When all values are within the goal of 0.75%, congratulations, you calibrated your non-Pe section of your MAF table using STFT and your narrow band 02 sensors.

Now that you calibrated the non-Pe portion of the MAF table, you can click on the 2D view of the MAF Airflow vs. Frequency table in your working MAF tune and look at the curve. You will see that the curve wants to go in in a certain direction compared to your stock calibration, often 10% leaner than stock but not always. What I do is click on the line and manually drag the curve (manual interpolation). This is optional but it helps get the job done quicker for the next step. If you do not have a wideband, this is as far as you can go anyway. You do not want a shelf where the new calibrated data stops and the stock Pe portion of the curve starts so smoothing the curve is a good idea. Flash the tune into the truck in prep for the WOT calibration. If you will NOT be doing the WOT cal, copy the new MAF calibration into your starting tune that you did not to write over and flash back into your truck.

[AlanDC]

Nice write up. I?m following this post because I have a 1998 C1500 truck 5.7L and 4L60E that has almost identical PCM setup. I have another add ons on my engine (headers, spark plug cables, ignition module, hand ported stock heads, cam) but I?m learning a lot from you 2.

I?ve attached my stock tune and I?ve made some minor changes to it (in a diff. file attached too). Now with this COVID19 thing I?m not able to drive out on the street, just 2 days a week and with a lot of restrictions. So, I believe I?ll be doing the MAF and VE calibrations after a couple weeks. Actually I?m in Medellin - Colombia

Also, can you share the modified file after your airflow calibrations?

I?ve not messed with Airflow and spark advance yet. But after the engine calibrations I will be playing with shift pressures (I want firmer shifts) and scheduling (to stretch it a little). Also I?ve seen the PCM has a pin for an engine cooling fan and now I see that option in the system tab that I can turn ON. Since I did the electric fan conversion, any of you have tried that feature? Any advice will be really appreciated!

I was thinking about starting a new thread but it looks like there?s just a few ppl tuning this early gen GM engines.

[MrFixIt86]

Not a great idea to paste hi octane to lo octane, I would suggest taking 5 degrees out of all timing tables to stay away from knock if fueling goes astray while calibrating. You should be able to do wot pulls just do it gradually, no quick throttle movements, steady smooth throttling. If you had a wideband you would normally fail the 02s as well but for now that's what you got I guess. Also you should watch some you tube videos, step by step show you all u want to know for now. Try goatrope garage on you tube. Your piecing it together though, keep it up. I found that on stock platform the fueling wont be too far off, you'll find your power by leaning those pe tables to 1.19 or 1.18 in your torque areas and maybe lean out in higher rpms to 1.15ish. Don't the 5.7s still have a distributor?

[MrFixIt86]

Oh and the rear 02s strictly monitor the cats so if you just don't enable the engine light on for all o2 sensor 2 codes they're essentially deleted. And maybe cat codes need turned off also. Let me know how things turn out, my cousin has a 99 Tahoe 5.7 that i'd like to make go a little faster for him.