Injectors Vs Fuel Pressure

[EagleMark]

IIRC they are all the same hex address, he just made them separate so you only need to change one. For fuel anyway, cylinder volume is differant. So calculate your injector flow at new pressure and enter it and the others change...

[BLG355]

Did you increase the injector rating under scalars when you raised the fuel pressure? If not, the calculated duty cycle will be the same.

I just did this, I changed nothing but the flow rating, the BLM's went right up to 165 pretty quick...It was at 69#, with 61# injectors at 25.5PSI I am all but to 90#. Is that normal for that to just up and change? I went through the data log and used Mark's tutorial on adjusting fuel tables on my first chip, but I did something wrong there because the BLM never moved off 128 and the O2 read 0mv constantly...so I figured I'd start small with changing the injector rating and run a data log to see where it is at. I'm just glad I can finally burn chips, I have a feeling I am going to learn a lot in the next few weeks.

[Roadknee]

I just did this, I changed nothing but the flow rating, the BLM's went right up to 165 pretty quick...It was at 69#, with 61# injectors at 25.5PSI I am all but to 90#. Is that normal for that to just up and change? I went through the data log and used Mark's tutorial on adjusting fuel tables on my first chip, but I did something wrong there because the BLM never moved off 128 and the O2 read 0mv constantly...so I figured I'd start small with changing the injector rating and run a data log to see where it is at. I'm just glad I can finally burn chips, I have a feeling I am going to learn a lot in the next few weeks.

What you observed is normal.

When you increased the injector rating the ecm thought you had bigger injectors so it reduced the pulse width to compensate. The injector rating only really needs to be adjusted to keep the numbers in the VE tables between 0 and 100. This is because you cannot input a number less than 0 or over 100 in the VE table. It won't save. In my stock LO5 my highest value in the VE table is 94 and the lowest is 40. If I halved the injector rating and cut the values in the VE table in half (high 47, low 20) the motor would run the same.

Could you post your VE table or current BIN?

Put the injector rating back where it was and go run a datalog. If you were too lean at WOT and your VE values were already at 100, you'd need to reduce the injector rating. If you reduced the injector rating by 5% and left the VE table values the same, the ECM would calculate pulse width to add 5% fuel throughout the entire operating range when in open loop.

[BLG355]

Here it is how I did it the first time when I updated the tables with the TBI Calculator. I didn't get to update all the data because with this fuel pressure I only ran two small logs, so I had limited counts on a lot of the cells. I figured I'd wait until I can burn the chips and go from there. So I updated the tables, changed the injector flow rating, but haven't logged it because it went mega lean. I will put the injector rating back and then run a log with the updated tables and see how that goes.


BLG

[BLG355]

I have my BB injectors on the truck now, I am going to swap them off and run these again (maybe) to get Bill to flow the BB injectors since I do not know what the flow. I have to put more pressure to these as I was maxing out the InjDC%, and even with the BB injectors, I need more pressure, currently running them at 14.7 psi.

BLG

I got flow numbers finally on my Napa mystery BB injectors.

Hi Barry,

Your injectors arrived. I have completed the flow tests. Here is what they flow static at 12 and 15 psi.

	12PSI	15PSI
CC/MIN	720	840
LBS/HR	68	80

There is a hard copy in the package. I have sent you a PayPal invoice and I'm ready to ship as soon as you can check out. Thanks again for the business! Bill

Bill Johnson / Mr Injector
6280 N Government Way Unit 4
Dalton Gardens, Idaho 83815


I was running them at 14.7 psi. It seemed flat on the top end with them, I was guessing that were 80lb replacements, apparently not. but now I now what I need to do to run them.

[Roadknee]

After you massage the VE tables with BLM data, remember to manually smooth the table. Parts of your current table look pretty bad. Open up the table and click the graph icon just to the right of the red X. Put the mouse pointer on the screen, hold the right button down and move the mouse to rotate the table. I usually put the lowest number (blue cells) on the lower right. Move the mouse pointer over the rough areas. lift click and move the extremely low areas up some and move the surrounding high areas down some to match. This doesn't have to be perfect when you're roughing it in.

[BLG355]

I smoothed it out and ran a log. BLM's are definitely getting closer now. I will decipher everything tomorrow and run it though the converter spread sheet. I still have glowing manifolds, not sure why. I did check again, after a hard pull they glow and also after running at highway speed and coming to a stop they have a slight glow. I know I have enough fuel, there is no vacuum leaks, maybe it needs more timing. I will play with it tomorrow. Very tired now and I don't want to make a mistake with this stuff, I have a hard enough time when I'm juiced on coffee let alone half asleep. Thanks again for everything so far, it's been a huge help.

Barry

[brian617]

One trick I learned when I changed my flow rate after already having a VE table started was to do one data log then move the entire table up or down to get the BLMs back in order.

I would assume that you'd want the injector flow rate to match the actual flow rate if you want your injector duty cycle and pulse width to be accurate in logs, could be wrong?

[Roadknee]

I would assume that you'd want the injector flow rate to match the actual flow rate if you want your injector duty cycle and pulse width to be accurate in logs, could be wrong?

I don't think it matters. The injector flow rate just needs t be close enough to keep the VE tables in check. The VE table values might be wrong, but it does not matter as long as fueling is right. BLG355's VE table has a max value of 93 where his engine is actually capable of near 100. He could increase both the VE tables and the injector flow rate 7% and the ECM would deliver the same pulse width and the engine would run the same.

[Roadknee]

I smoothed it out and ran a log. BLM's are definitely getting closer now. I will decipher everything tomorrow and run it though the converter spread sheet. I still have glowing manifolds, not sure why. I did check again, after a hard pull they glow and also after running at highway speed and coming to a stop they have a slight glow. I know I have enough fuel, there is no vacuum leaks, maybe it needs more timing. I will play with it tomorrow. Very tired now and I don't want to make a mistake with this stuff, I have a hard enough time when I'm juiced on coffee let alone half asleep. Thanks again for everything so far, it's been a huge help.

Barry

You did a good job smoothing the VE table and collecting the datalog. Lots of steady throttle and you captured many of the VE table cells. I have two suggestions for your next bin in addition to your next VE table fix. (1) under Power Enrichment Tables, change all the values in the "TPS for PE vs RPM" to 55% and all the values in "TPS for fast PE vs RPM" to 65%. This will hold you in closed loop a little longer so you can get good blm data in VE cells up to 90 kpa below about 3,500 rpm. Once you enter PE, it will transition to full PE sooner (65% tps vs 75% tps). (2) under scalars, BLM Update Parameters, change Maximum RPM for BLM Update Enable from 3,500 rpm to 5,500 rpm. This will allow you to get BLM correction data above 3,500 rpm.

[BLG355]

That does run really strong! My stock 1995 K1500 LO5 will pull 37 to 57 mph in second gear in just over 6 seconds. You're under 4. Wow!

I understand you're running base timing at 0 BTDC in this datalog. So your WOT timing is about 26 degrees. I think your combo could run 32-34 with your heads. Cruising at 2000 rpm and less than 50 MAP you're only running about 28 degrees total. I think your combo could use 40 or more. BLMs are rich in this area already and they'll become richer if you increase the timing so you'll need to reduce the VE tables too. These changes should reduce EGTs.

I think you could add 8-10 base timing for a quick test and go for a cruise to see how it impacts EGTs. Watch knock counts very closely if you're going to lean into the throttle.

When I was going through my first tuner, I couldn't get the truck to run on his chips at all, and being a new engine, I wanted to run it in. So he basically told me, advance base timing 10 degrees and run the stock chip, and the truck ran fairly well. So, I decided to take that stock timing table, add 9.8 across the board, and see what it does. I used the same tune I got from Mark originally, just modified what I had talked about on here with the BLM and now the timing. Is it safe to say I didn't add to much timing based on this? (see attachments)

[Roadknee]

Your cylinder heads will work much better with more timing than the stock swirl ports so its not surprising that adding 10 degrees overall works. IMO, your timing table posted above is better for your engine at about 50 MAP and below, but I like Marks better at WOT. I think you engine could us as much as 44 degrees below 50 MAP and 2,400 rpm and above. 25 degrees in the idle cells, and 30 degrees at 3,000 rpm at WOT increasing to 33 or so at 4,800. Give it a shot, blending the cells in between and let us know how it works.

[Fast355]

You did a good job smoothing the VE table and collecting the datalog. Lots of steady throttle and you captured many of the VE table cells. I have two suggestions for your next bin in addition to your next VE table fix. (1) under Power Enrichment Tables, change all the values in the "TPS for PE vs RPM" to 55% and all the values in "TPS for fast PE vs RPM" to 65%. This will hold you in closed loop a little longer so you can get good blm data in VE cells up to 90 kpa below about 3,500 rpm. Once you enter PE, it will transition to full PE sooner (65% tps vs 75% tps). (2) under scalars, BLM Update Parameters, change Maximum RPM for BLM Update Enable from 3,500 rpm to 5,500 rpm. This will allow you to get BLM correction data above 3,500 rpm.

I would set the setting for PE to 90% and FAST PE to 99%. Stock Vortecs run 90% PE settings all day long.

[Fast355]

Your cylinder heads will work much better with more timing than the stock swirl ports so its not surprising that adding 10 degrees overall works. IMO, your timing table posted above is better for your engine at about 50 MAP and below, but I like Marks better at WOT. I think you engine could us as much as 44 degrees below 50 MAP and 2,400 rpm and above. 25 degrees in the idle cells, and 30 degrees at 3,000 rpm at WOT increasing to 33 or so at 4,800. Give it a shot, blending the cells in between and let us know how it works.

On 87 octane I think that will be too much timing. My aluminum head, 215/220 cammed 350 Vortec in my Express only likes about 42* above 2,800 rpm and 40 kpa on 93 octane.

This table is working very well in a stock compression vortec head 350 with a fairly aggressive 268 roller cam, running on 87 octane.

[Roadknee]

I don't think his 72 cc chamber 165 cc intake volume dart heads are the same as Vortecs.