MAF and VE almost dialed in... but...
08-20-2008, 12:20 AM
#1
MAF and VE almost dialed in... but... So almost have everything dialed in quite nicely for the part throttle driving ie drivability. With SD mode on MAF disabled, DFCO off, PE off, LTFT trims are < +-10. MAF dialed in too. With the MAF enabled trims are +-5 with >2400rpm showing positive LTFT values but something like 1-3 mostly up to 4krpm.
My issue is that at 0.40-0.50 g/cyl in the 1400-1800rpm range, I am getting some knock retard. That would translate to a little over half throttle in high gear with some knock retard going as high as 6, but generally 3-5 for most of it. No retard anywhere else under part throttle.
Is there something else advancing the timing in that range that I don't know about? At first I thought it was the EGR system, but where I have EGR enabled doesn't correspond to any knock, ie EGR is only for below 0.40 g/cyl and the tables have 0 advance for 0.40. I'll run a test in the morning disabling my EGR and seeing if that really is or isn't the cause.
I'm so close to getting this down now. Already have a ridiculous amount of low torque that my 315's will break loose now if I go more than half throttle just after getting it to roll from idle.
Another tuning question, for idle does VE play a large role? Earlier on in my tuning I played with lowering the VE numbers in the low rpm and it seemed to cut my idle first gear bucking. Since playing with LTFT tuning along with MAF tuning, my VE was raised a bit down there as well and thus the first gear buck is back and mean as ever. I was also MAF tuning so I'm just trying to confirm a theory.
Tomorrow will be a good test for my tune in general too as the temp is set to rise ~10 degrees. I'm hoping to see the scan log cut fuel and go - from the LTFT accordingly to the rise in ambient temp.
My issue is that at 0.40-0.50 g/cyl in the 1400-1800rpm range, I am getting some knock retard. That would translate to a little over half throttle in high gear with some knock retard going as high as 6, but generally 3-5 for most of it. No retard anywhere else under part throttle.
Is there something else advancing the timing in that range that I don't know about? At first I thought it was the EGR system, but where I have EGR enabled doesn't correspond to any knock, ie EGR is only for below 0.40 g/cyl and the tables have 0 advance for 0.40. I'll run a test in the morning disabling my EGR and seeing if that really is or isn't the cause.
I'm so close to getting this down now. Already have a ridiculous amount of low torque that my 315's will break loose now if I go more than half throttle just after getting it to roll from idle.
Another tuning question, for idle does VE play a large role? Earlier on in my tuning I played with lowering the VE numbers in the low rpm and it seemed to cut my idle first gear bucking. Since playing with LTFT tuning along with MAF tuning, my VE was raised a bit down there as well and thus the first gear buck is back and mean as ever. I was also MAF tuning so I'm just trying to confirm a theory.
Tomorrow will be a good test for my tune in general too as the temp is set to rise ~10 degrees. I'm hoping to see the scan log cut fuel and go - from the LTFT accordingly to the rise in ambient temp.
08-20-2008, 12:53 PM
#2
I tuned the MAF via the HP Tuners FAQ and found that once the MAF was enabled again, LTFT went to hell and was trying to dump as much as 22 throughout the drivability range.
MAF vs STFT error was telling me to lower the MAF Airflow by a good 20%.
I restored my modified MAF settings (increased roughly 15-20%) and had it back to my +-5% which was in line with my SD tune which I had within 10% with the MAF disabled.
Also noted my EGR has nothing to do with my extra knock at half throttle 1400-1800rpm range. While not exactly a good indicator, it used to be that in first I could hammer it off a roll and break loose the tires, now I can break loose from a roll in 2nd... HP Tuners is fun. I'll play with some WOT tuning later on a dyno with AFR and wideband.
MAF vs STFT error was telling me to lower the MAF Airflow by a good 20%.
I restored my modified MAF settings (increased roughly 15-20%) and had it back to my +-5% which was in line with my SD tune which I had within 10% with the MAF disabled.
Also noted my EGR has nothing to do with my extra knock at half throttle 1400-1800rpm range. While not exactly a good indicator, it used to be that in first I could hammer it off a roll and break loose the tires, now I can break loose from a roll in 2nd... HP Tuners is fun. I'll play with some WOT tuning later on a dyno with AFR and wideband.
08-20-2008, 01:03 PM
#3
Do you have updated knock sensors? I had similar trouble. From 99 on, GM used different knock sensors & modified the the knock software. The upgraded software is less sensative. Once I replaced the 98 knock software w/ a modified version of the 99+ knock software, the "false knock" went away. You could also try to desensitize the knock sensors by changing the sensativity value, but, it won't make much difference. So, my suggestion is to upgrade the knock sensors & to download the 99+ knock software.
08-20-2008, 05:04 PM
#5
I set MAF failure to 0 HZ while keeping it connected then lowered the High RPM disable to 500 to allow readings from the MAF. I then made sure I was in SD mode and shut off LTFT and basically mapped the frequencies up to 8000hz taking 150 cell hits roughly per cell.
08-20-2008, 06:35 PM
#7
ughhh... I was typing in quick, but basically I was following a MAF procedure outlined on the HP Tuner's website.
In the past few days so much info so I got my tune for this and that crap all confused. Wrote what I did for SD tuning in previous post. So much stuff you can do, but after following this procedure, I found my MAF to be way off so I just went along the lines of raising my MAF calibration up by 3% until I got the LTFT to be within +-5%. My SD VE Tables are already within +-5% based on a LTFT Tuning Guide found here on LS1Tech.
1. Open your file in the editor and turn off the LTFT's in the Engine > Open/Closed Loop tab. Either select the Enable/Disable switch or set the Min Temp to Enable to 283F or do both if you wish.
A. Save this file as Rev 1x.hpt or whatever you like. Just make sure it's a different file name and don't write over your stock file!!!
2. Program the cal to the PCM using "Write Calibration Only"
3. Turn on the key, open the scanner, start scanning and open the "VCM Controls"
A. Go to the "Fuel & Spark" tab and press "Reset Fuel Trims" to clear out any LTFT's that were stored.
B. stop scanning - no point in logging a non-running engine.
C. Go to the MAF - STFT histogram(s) and then click on the [C] for cell counts.
D. Restart scanning.
4. Start the car & drive. Try to overlap MAF regions with different RPM's so that you get a very good average with different RPMs.
5. When you have at least 100+ hits (I shoot for 150+) in all of the lower Hz (below 4500 Hz) and tapering down in hit counts above 4500 Hz. I generally don't like hit counts with STFT's below 20.
Note: You can usually get to 6600 Hz without tripping PE fueling but my config filters out those PE fueling hits anyway.
6. Once the data is aquired, click the [A] for [A]verage STFT, select the entire MAF -STFT Filt5 histogram and copy all the data from there (Control - C).
7. Open the editor with your current file and go to the MAF table under Engine > Airflow.
8. Select the entire MAF table and right click, Paste - Special Multiply %
9. Save as a new file (Rev 1b.hpt etc...)
10. Write to the PCM with a Write Calibration Only.
11. Repeat as necessary until the error is in the +/- 1-2% range.
In the past few days so much info so I got my tune for this and that crap all confused. Wrote what I did for SD tuning in previous post. So much stuff you can do, but after following this procedure, I found my MAF to be way off so I just went along the lines of raising my MAF calibration up by 3% until I got the LTFT to be within +-5%. My SD VE Tables are already within +-5% based on a LTFT Tuning Guide found here on LS1Tech.
1. Open your file in the editor and turn off the LTFT's in the Engine > Open/Closed Loop tab. Either select the Enable/Disable switch or set the Min Temp to Enable to 283F or do both if you wish.
A. Save this file as Rev 1x.hpt or whatever you like. Just make sure it's a different file name and don't write over your stock file!!!
2. Program the cal to the PCM using "Write Calibration Only"
3. Turn on the key, open the scanner, start scanning and open the "VCM Controls"
A. Go to the "Fuel & Spark" tab and press "Reset Fuel Trims" to clear out any LTFT's that were stored.
B. stop scanning - no point in logging a non-running engine.
C. Go to the MAF - STFT histogram(s) and then click on the [C] for cell counts.
D. Restart scanning.
4. Start the car & drive. Try to overlap MAF regions with different RPM's so that you get a very good average with different RPMs.
5. When you have at least 100+ hits (I shoot for 150+) in all of the lower Hz (below 4500 Hz) and tapering down in hit counts above 4500 Hz. I generally don't like hit counts with STFT's below 20.
Note: You can usually get to 6600 Hz without tripping PE fueling but my config filters out those PE fueling hits anyway.
6. Once the data is aquired, click the [A] for [A]verage STFT, select the entire MAF -STFT Filt5 histogram and copy all the data from there (Control - C).
7. Open the editor with your current file and go to the MAF table under Engine > Airflow.
8. Select the entire MAF table and right click, Paste - Special Multiply %
9. Save as a new file (Rev 1b.hpt etc...)
10. Write to the PCM with a Write Calibration Only.
11. Repeat as necessary until the error is in the +/- 1-2% range.
