VE BLM tuning via Dave’s spreadsheet

[majacoby]

I have followed the instructions in the 7747 ve1 + ve2 thread. I have run the history though the spreadsheet changes a lot of times. There are always differences. Anywhere from a BLM of 120 to 140. When do you call it time to quit tuning BLM and move on?

I also followed a thread on building a history table called “Main VE BLM History”.
On the History I have been using “History Average”. Would that be the correct View for Main VE BLM History?

Thanks, MarkJ

[EagleMark]

When your between 120 and 140... smooth the table and move on.

Here's some things needed to record good data to use in the spreadsheet.

1. Disable all items in XDF under Turn Off For Data Logging.
2. Burn chip and install.
3. Drive rig around till warmed up, disconnect power from ECM to clear BLM/LTFT cells.
4. Start vehicle and when it enters Closed Loop, start data.
5. Find a good stretch of road. 10% throttle until it runs out. 20%... 30-40%... 60%... 80%... do all these if you can with no throttle movement. (100% WOT won't help and the only way to get that perfect is with WB)
6. Apply the BLM data to spread sheet, corrected VE to bin.
7. Use the graph in Main VE table to find the edges on data you installed and smooth the rest of the table that was not corrected.
8. Burn that bin and re test for BLMs after warmed up and BLM/LTFT cleared. It should be spot on, if within 120- 140 your done, BLM learn will trim to perfect.
9. Tun parameters back on in XDF that you turned off for data logging.
10. Burn final chip and enjoy!

That's the basics, some more to think about is no more then 90-95% in VE table. When done I take out some from VE1 and put it back in VE2. Watch Injector duty cycle espaically at WOT and make sure it stays below 80% or so, don't want to go static on injectors.

HTH!

[dave w]

I have followed the instructions in the 7747 ve1 + ve2 thread. I have run the history though the spreadsheet changes a lot of times. There are always differences. Anywhere from a BLM of 120 to 140. When do you call it time to quit tuning BLM and move on?

I also followed a thread on building a history table called “Main VE BLM History”.
On the History I have been using “History Average”. Would that be the correct View for Main VE BLM History?

Thanks, MarkJ

History Average is correct.

The spreadsheet is accurate when following the suggestions from EagleMark. It's not always possible, but I try to keep the VE numbers not much lower that the low 40's and not much higher than the mid 90's. Using the "Averaged" table at the bottom of the spreadsheet helps from overshooting when correcting Rich / Lean. The "Average" table is the calculated changed averaged with the old VE value, so it only changes the new VE value half of the calculated value. Smoothing helps because the ECM interpolates between surrounding cells. What the ECM does say at 2200 RPM's is look at the VE Values of both 2000 RPM's and 2400 RPM's to interpolate a VE value for 2200 RPM's. Sometimes fixing the VE table requires making the VE value at 2000 RPM's more to correct for a lean value at 2400 RPM's. The VE Table will not always be smooth, but it's logical the engine at high RPM's will need more fuel than an engine at low RPM's. It's also logical the engine will need more fuel at 2000 RPM @ 100 Kpa than an engine at 2000 RPM's @ 40 Kpa. It's also logical that some cells are not going to be populated when data logging, its not very likely to record a 3200 RPM's at 30 Kpa, well maybe with a 6 mile / 6% grade downhill in second gear? Its OK to have BLM's in the low 120's at HIGH RPM's and BLM's of low 130's at LOW RPM's. Its NOT OK to have LOW 130's or higher BLM's at high RPM's!!

dave w

[RobertISaar]

when knocking out a VE table, if you have a cell that looks odd, interpolate between the next highest and next lowest MAP range for the RPM that looks odd. you can have an engine that wants less fuel at a higher RPM or more fuel at a higher RPM, but you will never run into a situation where for a given RPM, a higher MAP requires less fuel.

[majacoby]

This is all great info for VE tuning!
This is almost worth putting in a place when people are first starting out.
Thanks, MarkJ

[majacoby]

Here is what my History has been looking like. Of course not all of the cells are filled in. The truck runs a whole lot better then it did with a stock chip burn.
23 Jan History2.jpg
It looks like it's time to move on.

[dave w]

Here is what my History has been looking like. Of course not all of the cells are filled in. The truck runs a whole lot better then it did with a stock chip burn.
23 Jan History2.jpg
It looks like it's time to move on.

I think I would have all the 80 ~ 100 KPA's at or just below 128. In the screen shot, I'm seeing some of the 80 ~ 100 KPA near 135. Having BLM's of 135 in 30 ~ 50 KPA's is almost acceptable. To be honest, I think BLM's of 135 in the 80 ~ 100 KPA's is unacceptable.

dave w

[EagleMark]

I think I would have all the 80 ~ 100 KPA's at or just below 128. In the screen shot, I'm seeing some of the 80 ~ 100 KPA near 135. Having BLM's of 135 in 30 ~ 50 KPA's is almost acceptable. To be honest, I think BLM's of 135 in the 80 ~ 100 KPA's is unacceptable.

dave w

That's the way I feel, more because of lean cruise and when it is entered!

But for PE on $42 it is not crucial.

In PE mode: Learn is turned off and the INT is locked at 128. If the BLM is < 128 it is ignored (128 is used). If the BLM is >= 128 it is then used.

IIRC $0D is differant for PE?

[EagleMark]

Here is what my History has been looking like. Of course not all of the cells are filled in. The truck runs a whole lot better then it did with a stock chip burn.
23 Jan History2.jpg
It looks like it's time to move on.

Like Dave said...I'm not sure I like those 13x numbers in 90 MAP? Seems like it is running out of fuel there? How does the Main VE table look? What is your fuel pressure and did you set BPW? If this is a built motor and your going to run higher RPM then that it could be on the lean side and get worse.

It looks fine other then that. I'm just not used to seeing high numbers pop up in 90 MAP after the rest is so close...

[majacoby]

23 Jan VE1 chart.jpg23 Jan VE1.jpg
I think you are correct that it’s running out of fuel at the top end. I do not know what the fuel pressure is. What a PIA it is to get the fuel pressure on a 1990 K1500 350 TBI!
I bought an adapter that goes between the high pressure line and the TBI inlet. It has a 1/8 pipe thread for a pressure gauge but have not it installed yet. I need to replace the fuel line anyhow, so I guess it’s a good time to do it.
When you say set BPW do you mean to the Hack (00AB00AC or do you mean “Base Pulse Width (135.00)??
BTW I think the chart and the 3d are different.
Thanks, MarkJ

[dave w]

23 Jan VE1 chart.jpg23 Jan VE1.jpg
I think you are correct that it’s running out of fuel at the top end. I do not know what the fuel pressure is. What a PIA it is to get the fuel pressure on a 1990 K1500 350 TBI!
I bought an adapter that goes between the high pressure line and the TBI inlet. It has a 1/8 pipe thread for a pressure gauge but have not it installed yet. I need to replace the fuel line anyhow, so I guess it’s a good time to do it.
When you say set BPW do you mean to the Hack (00AB00AC or do you mean “Base Pulse Width (135.00)??
BTW I think the chart and the 3d are different.
Thanks, MarkJ

I think Mark was talking about BPW 135. Looking at your VE table, I would increase the BPW from 135 to 137 to help get the higher KPA numbers into the upper 120's. Not everyone tunes the same way, so there will be other opinions on how to get the higher KPA numbers into the upper 120's.

dave w

[EagleMark]

We are talking the Paremater BPW. It should be 135 stock.

Darn good looking fuel table!

Daves being polite! We have been back and forth with the BPW, I keep testing his theory of raising it to boost some fuel at top end and since the last time we discussed this I've found it does work accuratly only about 10 over what was stock or what was calculated. After that it turns into a fueling curve instead of a straight line. Dave can still tune it!

You could try and add 10 to BPW with the same tune and re data log. See where the whole BLM table goes? It should go down across the board.

But look at your Main VE table. Where you are going into 135 BLMs your VE table is already mid 90%, your already at the limit and even beyond in cells further up to 96%. Your on the edge or more accuratly past the edge and if going any higher RPM it's only going to get worse! Your log is only showing to 2400 RPM, even a stock motor is capable of much more!

You need more fuel!
Whether it's filter time or and old pump or when you get a fuel pressure reading and it's under 13psi?
You need more fuel!

Post a data log! If you have installed the BPW hack we can watch BPW in ms and the injector duty cycle. BPW value in ADX file needs to have your injector bias correct in conversion.

[majacoby]

Attached are my out come after setting BPW to 145. This isafter making the adjustments to the VE1 from the spreadsheet with Historyaverage.
I think I’m running out of fuel up in the 2400 area. I knowwhat I have to do next. Fuel filter and adjust pressure.
Am I going in the right direction?
MarkJ

24 Jan VE1 BPW 145.jpg24 Jan hist Avg 3d bpw 145.jpg

[dave w]

Attached are my out come after setting BPW to 145. This isafter making the adjustments to the VE1 from the spreadsheet with Historyaverage.
I think I’m running out of fuel up in the 2400 area. I knowwhat I have to do next. Fuel filter and adjust pressure.
Am I going in the right direction?
MarkJ

24 Jan VE1 BPW 145.jpg24 Jan hist Avg 3d bpw 145.jpg

It appears BPW of 145 lowered the BLM's into the 120's for KPA's 80 ~ 100 range below 2400. The downside to BPW 145 is the KPA's 30 ~ 60 range are mostly below 120 which is too rich. I think I would go back to the first VE table and try BPW 140. What I think is likely to happen is the low RPM's / low KPA's will be slightly rich, so the high RPM's / High KPA's will have enough fuel.

I really wish GM would have used a vacuum referenced fuel pressure regulator on the TBI. I've seen the TBI VE table Tug-O-War several times ... add fuel pressure to get good BLM's at high RPM's / high KPA's but end up with to much fuel at low RPM's / low KPA's. With a vacuum referenced fuel pressure regulator, the fuel pressure is increased (goes up in pressure) at the high RPM's / high KPA's yet for low RPM's / low KPA's the fuel pressure is lowered (goes down in pressure) to get good BLM's.

dave w

[RobertISaar]

I really wish GM would have used a vacuum referenced fuel pressure regulator on the TBI.

TBI injectors fire into atmospheric pressure air, correct?