Anyone tune a MAF yet?
01-08-2007, 02:01 PM
#1
Anyone tune a MAF yet? I wanted to know If I can tune the VE table on one day and the MAF on another. Is this OK or will it not be accurate? It takes me 3 log sessions to tune the VE table and by the time I finish the VE table its getting dark and the temp is dropping throwing of the VE table in SD mode.
01-08-2007, 02:11 PM
#2
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Get the VE table close (+/- 2%), enable the MAF and tune for it. The VE table (or the tune for that matter) will never be perfect. You'll waste hours trying to get it that way. Closed-loop will keep the AFR at 14.7:1 once re-enabled. Keep it slightly on the rich side for part throttle. Then, focus on WOT. Again, it will vary from day to day. So target 12.8 instead of 13.0 to leave yourself a little wiggle room. Dial it in and call it quits. Don't sweat the small stuff...
01-08-2007, 05:52 PM
#3
Originally Posted by SSpdDmon
Get the VE table close (+/- 2%), enable the MAF and tune for it. The VE table (or the tune for that matter) will never be perfect. You'll waste hours trying to get it that way. Closed-loop will keep the AFR at 14.7:1 once re-enabled. Keep it slightly on the rich side for part throttle. Then, focus on WOT. Again, it will vary from day to day. So target 12.8 instead of 13.0 to leave yourself a little wiggle room. Dial it in and call it quits. Don't sweat the small stuff...
01-08-2007, 06:05 PM
#4
Originally Posted by WS6HUMMER
Thanks but setting the MAF fail back to 14000Hz & plugging up the MAF again on a SD tune wont make it go back into CL will it? I'm so dumb, please forgive my ignorance. If it does go back into CL then I can tune the MAF a week after tuning the VE table and it will be just fine right?
01-08-2007, 06:06 PM
#5
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Running a MAF or running MAF-less (speed density) has nothing to do with open or closed loop. That's simply the method the PCM uses to determine current airflow, which is then used to determine the amount of fuel required based on inputs from the other sensors (IAT, MAP, etc.).
Open loop means the O2 sensors are not being used. It's a linear fueling process. The numbers are calculated and that's the end of it. When the PCM starts adjusting fueling based on the O2 sensors, you're effectively bending that linear process into a loop (aka closed loop).
You don't go back to closed loop until you reset the temps in the Close Loop Temp Enable table....regardless of whether you're running a MAF or not.
Open loop means the O2 sensors are not being used. It's a linear fueling process. The numbers are calculated and that's the end of it. When the PCM starts adjusting fueling based on the O2 sensors, you're effectively bending that linear process into a loop (aka closed loop).
You don't go back to closed loop until you reset the temps in the Close Loop Temp Enable table....regardless of whether you're running a MAF or not.
01-09-2007, 08:17 AM
#6
Originally Posted by SmokingWS6
Closed loop will function with the maf on or off. If you did a standard ve tune, you were in closed loop. If your wanting true 'sd' mode then you'd have to disable closed loop by maxing out the CL enable temps. You'd then have to set your desired afr for all conditions.
01-09-2007, 12:27 PM
#7
Originally Posted by SSpdDmon
Open loop means the O2 sensors are not being used. It's a linear fueling process. The numbers are calculated and that's the end of it. When the PCM starts adjusting fueling based on the O2 sensors, you're effectively bending that linear process into a loop (aka closed loop).
Originally Posted by SSpdDmon
You don't go back to closed loop until you reset the temps in the Close Loop Temp Enable table....regardless of whether you're running a MAF or not.
Bottom line is, it would be better to tune the car's VE table and MAF on the same day in the same weather conditions. Otherwise it would be inaccurate..........Right?
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01-09-2007, 03:48 PM
#8
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Originally Posted by WS6HUMMER
Right but the numbers the PCM's using to calculate fueling are the numbers in the VE table cells based on the amount of incoming air. Right? If I understand this right then it would be best to tune the MAF the same day you tune the VE table because the miniute the air changes the VE table becomes less accurate throwing off the actual amount of MAF error % I log right?
It would be best, but not 100% required. Again, it needs to be close. Not dead-on ***** accurate....and yes, that's an industry term.
OK now that you posted this, I understand that even though I re-enable the MAF I still will be getting my fuel calculations from the VE table only and wont ever use the narrow band O2 sensors or fuel trim learn until I set all that stuff back.
No. Again, the MAF has nothing to do with open loop. The VE works alone in speed density (no MAF) to calculate airflow. If the MAF is enabled, you're not in speed density. You're using a combination of the MAF & VE below 4,000 RPMs and the MAF above 4,000 RPMs.
Bottom line is, it would be better to tune the car's VE table and MAF on the same day in the same weather conditions. Otherwise it would be inaccurate..........Right?
It would be best, but not 100% required. Again, it needs to be close. Not dead-on ***** accurate....and yes, that's an industry term.
OK now that you posted this, I understand that even though I re-enable the MAF I still will be getting my fuel calculations from the VE table only and wont ever use the narrow band O2 sensors or fuel trim learn until I set all that stuff back.
No. Again, the MAF has nothing to do with open loop. The VE works alone in speed density (no MAF) to calculate airflow. If the MAF is enabled, you're not in speed density. You're using a combination of the MAF & VE below 4,000 RPMs and the MAF above 4,000 RPMs.
Bottom line is, it would be better to tune the car's VE table and MAF on the same day in the same weather conditions. Otherwise it would be inaccurate..........Right?
............
01-09-2007, 04:47 PM
#9
Originally Posted by SSpdDmon
............
I did a VE SD tune and pasted the corrected VE tables to my old CL/OL MAF tune, commanded 12.8 AFR (1.14 on the EQ vs RPM table) and now @ WOT I'm seeing 13.4. That's why I'm so interested in tuning the MAF now, I'm thinking that's now what I need to tune. Am I right in assuming that the MAF is what needs to be tuned so that I will get the AFR I command?
