Startup Frictional Airflow? Decay? Delay?
Startup Frictional Airflow? Decay? Delay? Alright, so I am having issues with startups both cold and hot. It starts and grabs 1000 rpms for about 5 seconds and then hunts wildly(4-600 rpms hills) for about 2-3 minutes and then gets smooth and runs great after that. RAF is in-line, I have changed the overspeed/underspeed but they didnt help, I have increased spark tables and nothing changes.
I was told that maybe the Friction Airflow Initial, Delay, and Decay (also startup initial airflow/delay) may be to blame but I cant figure out what the heck they actually mean. Once I got the RAF inline, I logged startup airflow. The car ran smooth (first five seconds) while the startup airflow was decaying and then once it hit zero the hunting began. Although I still cant figure out what changes to make it become smooth again after the hunting is done.
I was told that maybe the Friction Airflow Initial, Delay, and Decay (also startup initial airflow/delay) may be to blame but I cant figure out what the heck they actually mean. Once I got the RAF inline, I logged startup airflow. The car ran smooth (first five seconds) while the startup airflow was decaying and then once it hit zero the hunting began. Although I still cant figure out what changes to make it become smooth again after the hunting is done.
Last edited by 99whitews6; May 8, 2006 at 05:55 PM.
Originally Posted by TAQuickness
Might help if you increase the values in the startup friction, and lower the values in the startup friction decay table.
Idle Startup Friction Airflow Initial(I assume you mean this one): Is this g/sec added to the RAF or does it take place of the RAF? Or what does the value mean?
Idle Startup Friction Airflow Decay( i assume you mean this one as well): What the heck do these values do? It says this value is subtracted from the initial value, what initial value? What is the point of this table?
Originally Posted by 99whitews6
Can you explain what these mean?
Idle Startup Friction Airflow Initial(I assume you mean this one): Is this g/sec added to the RAF or does it take place of the RAF? Or what does the value mean?
Idle Startup Friction Airflow Initial(I assume you mean this one): Is this g/sec added to the RAF or does it take place of the RAF? Or what does the value mean?
Originally Posted by 99whitews6
Idle Startup Friction Airflow Decay( i assume you mean this one as well): What the heck do these values do? It says this value is subtracted from the initial value, what initial value? What is the point of this table?
For instance, assume you are starting the car and the ECT is 68*C. The PCM looks up the the initial SUFC value (in my case 3.990) and adds 3.990 to the RAF value.
The PCM then waits 5 camshaft revolutions (startup friction decay delay)before it starts to decay the SUFC (3.990).
After 5 camshaft revolutions, the pcm will look up the decay rate from the startup friction decay table. This number on my tune is ~0.037109. Every time the crank shaft rotates 90 degrees, 0.037109 will be subtracted from 3.990 until the SUFC = 0.
Make sense?
If you want to send it over I'll take a look at it. I have been able to perfect idle tuning on many cars locally. prostreetmotorsports@comcast.net
Last edited by Phil99vette; May 8, 2006 at 06:26 PM.
Originally Posted by Phil99vette
If you want to send it over I'll take a look at it. I have been able to perfect idle tuning on many cars locally. prostreetmotorsports@comcast.net
Originally Posted by TAQuickness
When you start the engine, the PCM samples the coolant temp. It then looks up the corresponding value from this table and adds it to the RAF value. When you start the engine, it needs more air until the rotating componets warm up.
These values determine how long it will take to decay the initial value.
For instance, assume you are starting the car and the ECT is 68*C. The PCM looks up the the initial SUFC value (in my case 3.990) and adds 3.990 to the RAF value.
The PCM then waits 5 camshaft revolutions (startup friction decay delay)before it starts to decay the SUFC (3.990).
After 5 camshaft revolutions, the pcm will look up the decay rate from the startup friction decay table. This number on my tune is ~0.037109. Every time the crank shaft rotates 90 degrees, 0.037109 will be subtracted from 3.990 until the SUFC = 0.
Make sense?
These values determine how long it will take to decay the initial value.
For instance, assume you are starting the car and the ECT is 68*C. The PCM looks up the the initial SUFC value (in my case 3.990) and adds 3.990 to the RAF value.
The PCM then waits 5 camshaft revolutions (startup friction decay delay)before it starts to decay the SUFC (3.990).
After 5 camshaft revolutions, the pcm will look up the decay rate from the startup friction decay table. This number on my tune is ~0.037109. Every time the crank shaft rotates 90 degrees, 0.037109 will be subtracted from 3.990 until the SUFC = 0.
Make sense?
But would it be appropriate to decrease the decay enough to make it add air for 2-3 minutes? Last edited by 99whitews6; May 8, 2006 at 06:43 PM.
Trending Topics
i have been having the same exact prob. i have got my RAFs in line for the most part and i have jacked with start up air flow and frictional air flow and the delays and decays and still cant get it to do well for me. if someone would look at it for me also i would really appericate it.
* sorry not trying to hijack but i cant get it to work and am getting flustered
* sorry not trying to hijack but i cant get it to work and am getting flustered
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Originally Posted by SUTTERERMAN85
* sorry not trying to hijack but i cant get it to work and am getting flustered
Just kidding! As long as we can get this figured out!
ok sweet well i just messed a little more with it and it seemed to have helped. i had the frictional airflow decay at .5 not .05 thats a big difference. that was contributing to the prob. i have a post on the HPTuners site about my prob and a guy named ECTune and a couple others are helping me out. i have my delay set at 60 cam revs and its a bit much but it has helped it from surging after a few seconds. i have also messed with the deacy some and have made it decay slower and that has seemed to help quite a bit also. if you want to send me you tune i would like to look at it if you dont mind. i am curious about your AC offsets and a few other things. havent seen much in the bin repository about this stuff being changed and wonder if you had. if you dont mind sending it send it to me at nicksutterer@sbcglobal.net. thanks
nick
nick
Originally Posted by SUTTERERMAN85
ok sweet well i just messed a little more with it and it seemed to have helped. i had the frictional airflow decay at .5 not .05 thats a big difference. that was contributing to the prob. i have a post on the HPTuners site about my prob and a guy named ECTune and a couple others are helping me out. i have my delay set at 60 cam revs and its a bit much but it has helped it from surging after a few seconds. i have also messed with the deacy some and have made it decay slower and that has seemed to help quite a bit also. if you want to send me you tune i would like to look at it if you dont mind. i am curious about your AC offsets and a few other things. havent seen much in the bin repository about this stuff being changed and wonder if you had. if you dont mind sending it send it to me at nicksutterer@sbcglobal.net. thanks
nick
nick
Right now mine takes 20 seconds and its WAY to short.
not realy sure on how long it takes to finally decay all the way. i have the delay at 60 revs and that equates to about8 seconds or so and then i have slowed my decay down and its really much slower than it was before. its prob close to 20 seconds before it was about 3 seconds. send me your bin file and would like to look at it.
