IAC position vs effective area
04-24-2005, 09:18 AM
#81
now back to the airflow table for idle, like i said the difference in my numbers is -0.20 lb/hr
once i get all my dynamic airflow values right, do i convert to gms/sec and subtract this number out of the table? it looks like the LTIT stays the same number all the time and then the STIT is the one that changes after i tried to make an adjustment
once i get all my dynamic airflow values right, do i convert to gms/sec and subtract this number out of the table? it looks like the LTIT stays the same number all the time and then the STIT is the one that changes after i tried to make an adjustment
04-24-2005, 10:00 AM
#82
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P Mack - You are the man...
My IACDES_B and Dynair finaly match, the MAF is close enough for government work and my idle LTFT's and STFT's are spot on.
Now all I need to do is take the test drive.
FWIW, I ended up shifting the cells 8 positions to the left so my effective area starts at 28.
ScreenShot:
My IACDES_B and Dynair finaly match, the MAF is close enough for government work and my idle LTFT's and STFT's are spot on.
Now all I need to do is take the test drive.
FWIW, I ended up shifting the cells 8 positions to the left so my effective area starts at 28.
ScreenShot:
04-24-2005, 12:34 PM
#83
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Originally Posted by TAQuickness
My IACDES_B and Dynair finaly match, the MAF is close enough for government work...
04-24-2005, 01:04 PM
#84
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Ok, reverting back to RAF (yes it means running airflow from the Edit days) and this Des vs. Dyn IAC. Is it better to adjust the RAF back to stock and do this D&D IAC Cells adjustment, or do the adjustment with the RAFs as is? Kind of confused on this one. Sounding like a way to get the IACs in line, stop the surging and not have any cruise control effect....which is the same reason I changed all the RAFs and such before. I havent logged or even looked at the IAC info, so not sure where its all at.
Charlie
Charlie
04-24-2005, 01:10 PM
#85
Originally Posted by Another_User
You have a few choices for MAF table changes:
2) cell shift (I think I am the only person that does this, affects low airflow more than high airflow, can be mixed with scaling with pretty good results)
2) cell shift (I think I am the only person that does this, affects low airflow more than high airflow, can be mixed with scaling with pretty good results)
04-24-2005, 02:02 PM
#87
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WS6... so are your RAFs stock and you just simply modified the Dyn to Desired IAC by shifting cells as described? That would be cool. Now to order a new IAC Valve.
04-24-2005, 02:19 PM
#88
when i just shifted it worked no problem and the RAF numbers didnt seem to change much
once i get my VE table dialed in better im going to mess with the numbers some more. im gonna make a spread sheet that calcualates the opening based on known good numbers and dynamic air flow. but like i said i have to have accurate dynamic airflow numbers first (gettin my fuel trims in line)
i did notice however, that if you dont just shift and actually change certain cells and not the whole table that you will have to modify the RAF tables for this, it threw those numbers off a good bit and made the idle a little more harsh, so for right now i just shifted that table, and that did make a big difference in the way the car got back to idle and everything.
once i get my VE table dialed in better im going to mess with the numbers some more. im gonna make a spread sheet that calcualates the opening based on known good numbers and dynamic air flow. but like i said i have to have accurate dynamic airflow numbers first (gettin my fuel trims in line)
i did notice however, that if you dont just shift and actually change certain cells and not the whole table that you will have to modify the RAF tables for this, it threw those numbers off a good bit and made the idle a little more harsh, so for right now i just shifted that table, and that did make a big difference in the way the car got back to idle and everything.
04-24-2005, 03:26 PM
#89
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Originally Posted by 405HP_Z06
How exactly do you use this method? Sounds very interesting and sounds like it could be helpful for some air intakes because of unmetered air passing through the MAF sensor.
04-24-2005, 05:28 PM
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Originally Posted by WS6FirebirdTA00
another user, adjusting the RAF table using the proper trims, do you do it just like ve tuning?
04-24-2005, 05:47 PM
#92
Originally Posted by Another_User
No, I have tried that before, it didn't work out. I use what I like to call....fudge factor. Each cell shift left or right is good for about 10% fts on the low end of the scale, and multiplying the entire table is usually good for 10% fts on the high end. If you don't mind screwing around for a day or so you can usually get your trims pretty close without any crazy calculations. Not saying the other ways are worse, it is just an easier option for a complicated issue. I haven't broken out the MAF table spreadsheets and calculated a new one from anyone elses. I had made my own spreadsheet, but the results didn't seem good to me. The trims on the low end get a little too crazy for me. I might try their spreadsheet out though. There isn't much HPTuners has offered us that I have not tinkered with yet.
05-25-2005, 10:54 AM
#93
This is a great thread.... something that is very important for those of us with after-market throttle bodies.
My IAC seems to have an enormous, high flowing port. I have been trying to live with a 2500 rpm moving idle for a couple days and I think I really need to start working with the IAC effective area. I may need to do things like actually altering the effective area equal to a specific IAC postion, in other words, do more than moving the table up and down. I'll need to log derired airflow and actual at a few IAC positions (thanks HPT for giving me the ability to stick my IAC wherever I want) and then see what kind of airflow I get. Now... changing that to effective area is going to be.... more challenging. Also, the 2d curve isnt exactly a simple low polynomial function. Interpolation is going to be tricky, but I suspect required.
This should be a sticky of some kind for tuning idle with ported or aftermarket TBs.
My IAC seems to have an enormous, high flowing port. I have been trying to live with a 2500 rpm moving idle for a couple days and I think I really need to start working with the IAC effective area. I may need to do things like actually altering the effective area equal to a specific IAC postion, in other words, do more than moving the table up and down. I'll need to log derired airflow and actual at a few IAC positions (thanks HPT for giving me the ability to stick my IAC wherever I want) and then see what kind of airflow I get. Now... changing that to effective area is going to be.... more challenging. Also, the 2d curve isnt exactly a simple low polynomial function. Interpolation is going to be tricky, but I suspect required.
This should be a sticky of some kind for tuning idle with ported or aftermarket TBs.
10-12-2005, 05:13 PM
#98
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Bump.
This is great. Fixed my hanging rpms problem. I only had to move right two spaces.
Forget messing with Throttle Cracker. That made the idle drop, but it dropped to fast, then would search for idle. Now it's better.
Still fine tuning though. RAF is fine, timing fine, VE fine, IAC fine, but for some reason my rpms drop to about 500 when I start up, then go in reverse or forward the first couple times, sometimes stalls. GRR... Getting there though.
This is great. Fixed my hanging rpms problem. I only had to move right two spaces.
Forget messing with Throttle Cracker. That made the idle drop, but it dropped to fast, then would search for idle. Now it's better.
Still fine tuning though. RAF is fine, timing fine, VE fine, IAC fine, but for some reason my rpms drop to about 500 when I start up, then go in reverse or forward the first couple times, sometimes stalls. GRR... Getting there though.
05-15-2007, 09:35 PM
#99
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OK...I know this is an old thread but I wanted to throw a twist into it. My mods are in my sig and I'm using EFILive COS5 running in SD for clarifacation.
I played with idle, haunting and surging issues for a little while and reading the countless number of threads about each through many different forums, well, frustration set in. When I thought I had things nailed a new problem arose. Get rid of most surging, end up with hanging idle. Get rid of those and get a car that fires right up during the colder months then had to be cranked on once the weather warmed up. So here is what I did.
Pulled up a stock 2004 Z06 .bin and copied/pasted most idle tables into my tune. These included parameters, IAC Effective Area, Desired Airflow, Airflow Parked, Idle Spark Control Delay and Stall Saver RPM in the General Folder.
All Throttle Cracker, Throttle Follower and Rolling Idle tables.
I then moved to Spark and pasted High Octane, Low Octane, Base Spark in Gear and Base Spark in Park/Neutral tables over. I increased timing by 5* in the 400-1200rpm/.08-.36 cells and also in the 2000rpm/.08 cell.
I then set the throttle screw to obtain 35-40 IAC counts fully warm.
The car now starts right up cold or hot and hits desired idle right away and holds with slight rpm swings expected from a cam with overlap. It isn't much, maybe 20rpm either way. The surging has nearly disappeared and I have no hanging or dipping idle. I did try raising timing in those same areas a little more and did get a slight hang so I went back to the first setting.
Throttle is alot more crisp and the car drives a ton better.
After the changes I found this thread from a redirect from another site. When logging IACDES_B and DYNAIR they start cold with IACDES_B higher than DYNAIR and then as it warms they flop to DYNAIR higher than IACDES_B. Now these are reading in Lbs for some reason so maybe someone can shed light on that.
Now figuring all the above would shifting be a benefit and possibly make things even smoother running?
BTW. I actually had to close the throttle blade to get IAC counts in line after these changes.
I played with idle, haunting and surging issues for a little while and reading the countless number of threads about each through many different forums, well, frustration set in. When I thought I had things nailed a new problem arose. Get rid of most surging, end up with hanging idle. Get rid of those and get a car that fires right up during the colder months then had to be cranked on once the weather warmed up. So here is what I did.
Pulled up a stock 2004 Z06 .bin and copied/pasted most idle tables into my tune. These included parameters, IAC Effective Area, Desired Airflow, Airflow Parked, Idle Spark Control Delay and Stall Saver RPM in the General Folder.
All Throttle Cracker, Throttle Follower and Rolling Idle tables.
I then moved to Spark and pasted High Octane, Low Octane, Base Spark in Gear and Base Spark in Park/Neutral tables over. I increased timing by 5* in the 400-1200rpm/.08-.36 cells and also in the 2000rpm/.08 cell.
I then set the throttle screw to obtain 35-40 IAC counts fully warm.
The car now starts right up cold or hot and hits desired idle right away and holds with slight rpm swings expected from a cam with overlap. It isn't much, maybe 20rpm either way. The surging has nearly disappeared and I have no hanging or dipping idle. I did try raising timing in those same areas a little more and did get a slight hang so I went back to the first setting.
Throttle is alot more crisp and the car drives a ton better.
After the changes I found this thread from a redirect from another site. When logging IACDES_B and DYNAIR they start cold with IACDES_B higher than DYNAIR and then as it warms they flop to DYNAIR higher than IACDES_B. Now these are reading in Lbs for some reason so maybe someone can shed light on that.
Now figuring all the above would shifting be a benefit and possibly make things even smoother running?
BTW. I actually had to close the throttle blade to get IAC counts in line after these changes.