2000 7.4L MAF tuning black box

[alovelady]

I have a 2000 Chevy K2500 with the 7.4L and original black box computer. We installed a mildish cam and Bosch 30lb injectors. The engine will eventually be swapped into a 1995 OBS after we get it to run the way we want it to. I have been working on the VE tables (Primary and secondary) and it is just about done. Truck is running really good except for a little idle issues that will probably clear up once I let it go into closed loop. Does anyone have experience with tuning the MAF on these and could give me any pointers? Pretty much zero information on the web about these black box computers. I know everyone one says swap it to a 0411 but going for the complete factory look once its in the 95 OBS. I have attached my latest tune.

Thanks in advance!

[2xLS1]

It is no different than adjusting any other MAF table. Because it is a Black Box PCM makes no difference.

[Fast4.7]

I have a 2000 Chevy K2500 with the 7.4L and original black box computer. We installed a mildish cam and Bosch 30lb injectors. The engine will eventually be swapped into a 1995 OBS after we get it to run the way we want it to. I have been working on the VE tables (Primary and secondary) and it is just about done. Truck is running really good except for a little idle issues that will probably clear up once I let it go into closed loop. Does anyone have experience with tuning the MAF on these and could give me any pointers? Pretty much zero information on the web about these black box computers. I know everyone one says swap it to a 0411 but going for the complete factory look once its in the 95 OBS. I have attached my latest tune.

Thanks in advance!

The 0411 still looks stock. I have a P59 in my 99 Tahoe with an 8.1L.

[edcmat-l1]

You "tune" these like any other PCM. You're in speed density and attempting to dial in your VE tables. You're doing it wrong.

[alovelady]

You "tune" these like any other PCM. You're in speed density and attempting to dial in your VE tables. You're doing it wrong.

If I am doing it wrong could you point me in the right direction? Isn't speed density when you disable the MAF so you can tune the VE tables? If not what is the difference in speed density and VE tables?

[edcmat-l1]

If I am doing it wrong could you point me in the right direction? Isn't speed density when you disable the MAF so you can tune the VE tables? If not what is the difference in speed density and VE tables?

Yes. But for whatever reason the data you're using isn't producing realistic results. All VE tables should have a certain look to them, a certain shape. You're not supposed to have huge, gigantic spikes in fueling at low rpm low load areas.

[blindsquirrel]

(note: this isn't one of my usual smart-assed 'oh yeah? well then what about when...' questions)

I looked at the file, how DO you put one of these into MAF-only? I don't see anything like the later versions' dynamic airflow High RPM Disable/Enable. Is it just called something else, or located somewhere other than Airflow > Dynamic?

[edcmat-l1]

(note: this isn't one of my usual smart-assed 'oh yeah? well then what about when...' questions)

I looked at the file, how DO you put one of these into MAF-only? I don't see anything like the later versions' dynamic airflow High RPM Disable/Enable. Is it just called something else, or located somewhere other than Airflow > Dynamic?

Doesn't matter. As long as you fail the maf, it's in speed density. Even in the normal GEN3s you don't have to do anything with the dynamic airflow high and low.

[blindsquirrel]

He's asking how to tune the MAF. Thread title: "MAF tuning black box"

[edcmat-l1]

He's asking how to tune the MAF. Thread title: "MAF tuning black box"

Gotcha. Totally misread your post.

You can tune the MAF without putting it in "MAF only" using the dynamic airflow high and low. That doesn't really work on GEN3s anyway. You just have to have a steady foot.

[alovelady]

I didn't realize how far my graph got out of hand. I have smoothed it out a lot but still have some more to go. I do have a issue at very light throttle maintaining about 10-20 MPH it runs very lean. I keep adding fuel in those 2 cells but doesn't seem to help. At 45KPA, cells 1200 and 1600 RPM. Does it have something to do with cell 40KPA - 1200RPM being at such little fuel since that one is active at decel? Cells right next to each other going from one extreme to another extreme. Example is at 32 minutes 18 seconds on the log I have attached.

[edcmat-l1]

You should not have drastic changes numerically from 1 cell to another, 1 column to another, 1 row to another. The VE general shape just isn't right. I suggest putting it back in closed loop, unplug your wideband, forget about it and everything you've read about open loop tuning. It is a waste of time in 99% of the cases. Your computer doesn't care what the WB says and aftermarket WBs are notoriously inaccurate anyway. Put it back in closed loop. Disable your long-term trims and use your short-term trims to dial it in.

You want a shape that closely resembles the original VE table. I typically don't like them this smooth (screen shot), but it took a lot of smoothing to get rid of the peaks and valleys. Smooth the hell out of the primary and transfer it over to the secondary, put it back in closed loop, disable the LTFT and tune it using your STFT.

See the screen shots.

[alovelady]

I will give that a shot. Is there a certain histogram that I need to set up to record the short term error? Or do I just keep an eye on the short terms through out my drive and make my own adjustments?

[edcmat-l1]

I will give that a shot. Is there a certain histogram that I need to set up to record the short term error? Or do I just keep an eye on the short terms through out my drive and make my own adjustments?

I'm pretty sure there is a preconfigured GEN3 VE table all you'd have to do is setup to plot your STFT. If there isn't a table it's easy enough to create one. All the instructions are in your help menu.

[horsepowerguru427]

There are preconfigured STFT and LTFT for gen3 in the scanner. Although im a Fan of LTFT+STFT data logging which is not preconfigured but it is not hard to make a histo for that.
https://forum.hptuners.com/showthrea...h-STFT-HELP!!!

[Fast4.7]

On the Black Boxs if the MAF disable is not provided, I unplug the MAF. Trans will shift like it has a shift kit while it is unplugged, so do not do it for a long period of time if you like your transmission pump. I datalog and get the VE table dialed in to where it is between -5% and 0% on the fueling. I try to keep the fueling a bit rich and let the 02 sensor trim back the fueling as it needs to. Once you get the VE tables dialed in, plug the MAF back in. Now tune only the MAF table to get the fueling back to the same range. I have tuned probably 50 of the Black Box Vortecs in this manner and they run great for what they are. 0411 or P59 is much more accurate and just better all around even out of the box.

[edcmat-l1]

On the Black Boxs if the MAF disable is not provided, I unplug the MAF. Trans will shift like it has a shift kit while it is unplugged, so do not do it for a long period of time if you like your transmission pump. I datalog and get the VE table dialed in to where it is between -5% and 0% on the fueling. I try to keep the fueling a bit rich and let the 02 sensor trim back the fueling as it needs to. Once you get the VE tables dialed in, plug the MAF back in. Now tune only the MAF table to get the fueling back to the same range. I have tuned probably 50 of the Black Box Vortecs in this manner and they run great for what they are. 0411 or P59 is much more accurate and just better all around even out of the box.

1, setting the maf fail to zero and zeroing out the MAF table is the same as unplugging it.

2, to keep from shifting like it has a shift kit, disable the max line pressure under trans diag.

[Fast4.7]

1, setting the maf fail to zero and zeroing out the MAF table is the same as unplugging it.

2, to keep from shifting like it has a shift kit, disable the max line pressure under trans diag.

Not all tuning software has the MAF fail frequency option for all operating systems. I have tuned all black boxes from 96+ so I forget which ones have the fail and which ones do not. I typically tune the Black Boxes with Tunercats OBD2 though. Very seldom tune one with HPT since I am VIN Unlimited with Tunercats then again, I very seldom even tune a black box at all now. One of my first changes on these trucks is to throw a P01 or P59 into it.

If I am only VE tuning, I prefer to just let it shift a little firm since the line pressure can potentially be lowered while VE tuning resulting in slipping the clutches. My personal preference is I just let it shift a bit firm.

[alovelady]

Thanks for all of the reply's! As I get time and start trying the ideas I will report back on how things are going.