I just FREAKING love Idle tuning.....
12-09-2008, 09:47 PM
#12
The damn truck did want to idle after flashing in a new tune. I have almost got it, it took awhile... I followed the Idle tuning tutorial on EFI Live website and this is what I did: I added 2* of timing at idle, increased the Startup Friction Airflow Correction, lowered overspeed spark, raised underspeed spark, increased the Airflow Learning Control Delay and did the RAFPN/RAFGR thing.... Now it will actually run after loading tune!!!
12-09-2008, 09:52 PM
#14
damn, i never had a problem until i added the converter.... For some reason it just screwed everything up.... The strange thing is that the previous owner had the same problem, and the only other person I have seen with the same converter had the same problem too
12-09-2008, 11:07 PM
#18
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I can post here, it is just easier to talk in person. One hint is,
In tuning for idle,
The Computer uses SPARK before it will use the iac valve. It is faster than a physical motor movement. That is why there are spark correction values we put into efilive that are for the idle. Well, What that sets you up to do is :
Watch your commanded spark / actual spark being applied while idleing. if the number is higher or lower means that you need to modify the desired airflow up or down in that coolant temp to make it so the computer no longer adds or subtracts timing.
I set up a roadrunner pid on it so it does it for me, but you can do it manually.
Say the timing is higher than what you are asking for. So that means you need to add to the iac.
The computer also has a MASSIVE ability to learn itself. ON ANYTHING. You just have to turn on that ablility or add in values.
One thing people dont understand is, it is a computer, you can change the rules.
Spark for example. Alot of people dont understand how to change the way it works to make it better for you. You can change it so it can adjust itself alot faster between the high and low octane and how frequently it will try to go back to 100% high.
Back to the idle...
After you have changed that, usually it makes several other systems in the background you cant see useless as they are only there to prevent a stall condition. The desired airflow tab is pretty much the lowest most important value as it modifies all the other tables with it. If you change that you change all the adders as well. They become out of whack and usually over aggressive now..
The throttle cracker is usually the cause for alot of issues after you have a cam. It is what makes your car/truck hang idle as you are comming to a stop. then 3,2, 1 back down to your desired idle you are requesting. If you zero that out, since you dont need it anymore fixes that issue.
As for the issues after a torque converter, That is because you have changed ROTATING mass. So you need to correct your Airflow based on that, which would be the THROTTLE FOLLOWER tables. If you have a quicker reving motor you need to compensate in those tables so it wont allow it to drop off to quickly.. Alot of people confuse that function with just a heavy drivetrain. You can make it rev VERY fast comming down if you modify those values. It will make the engine SEEM faster and more responsive. You can however modify those to help make a car not come down so fast and create a surge.
ONE main thing that makes a surge is that the Commanded/actual idle the car wants to be is HIGHER than your actual rpm are.. So, you need to make sure your Actual idle at that point is less. For example, you are driving at 42mph the rpms are at 1100. if you put your foot in the clutch and it raises to 1400 then that means you have your tables wrong and that is the reason why you feel a jerk or a buck. If you lower that to say 900, then you will not see that issue.
Obviously there are other things that can attribute to the bucking like too much timing or invalid airfuel ratio but if those things are right, then the idle is the only thing left..
On the learning thing for the ecm. You can turn on things that will allow the pcm full control to tune itself. That is IF all your sensors are working like they should and there are no physical issues with your vehicle.
In tuning for idle,
The Computer uses SPARK before it will use the iac valve. It is faster than a physical motor movement. That is why there are spark correction values we put into efilive that are for the idle. Well, What that sets you up to do is :
Watch your commanded spark / actual spark being applied while idleing. if the number is higher or lower means that you need to modify the desired airflow up or down in that coolant temp to make it so the computer no longer adds or subtracts timing.
I set up a roadrunner pid on it so it does it for me, but you can do it manually.
Say the timing is higher than what you are asking for. So that means you need to add to the iac.
The computer also has a MASSIVE ability to learn itself. ON ANYTHING. You just have to turn on that ablility or add in values.
One thing people dont understand is, it is a computer, you can change the rules.
Spark for example. Alot of people dont understand how to change the way it works to make it better for you. You can change it so it can adjust itself alot faster between the high and low octane and how frequently it will try to go back to 100% high.
Back to the idle...
After you have changed that, usually it makes several other systems in the background you cant see useless as they are only there to prevent a stall condition. The desired airflow tab is pretty much the lowest most important value as it modifies all the other tables with it. If you change that you change all the adders as well. They become out of whack and usually over aggressive now..
The throttle cracker is usually the cause for alot of issues after you have a cam. It is what makes your car/truck hang idle as you are comming to a stop. then 3,2, 1 back down to your desired idle you are requesting. If you zero that out, since you dont need it anymore fixes that issue.
As for the issues after a torque converter, That is because you have changed ROTATING mass. So you need to correct your Airflow based on that, which would be the THROTTLE FOLLOWER tables. If you have a quicker reving motor you need to compensate in those tables so it wont allow it to drop off to quickly.. Alot of people confuse that function with just a heavy drivetrain. You can make it rev VERY fast comming down if you modify those values. It will make the engine SEEM faster and more responsive. You can however modify those to help make a car not come down so fast and create a surge.
ONE main thing that makes a surge is that the Commanded/actual idle the car wants to be is HIGHER than your actual rpm are.. So, you need to make sure your Actual idle at that point is less. For example, you are driving at 42mph the rpms are at 1100. if you put your foot in the clutch and it raises to 1400 then that means you have your tables wrong and that is the reason why you feel a jerk or a buck. If you lower that to say 900, then you will not see that issue.
Obviously there are other things that can attribute to the bucking like too much timing or invalid airfuel ratio but if those things are right, then the idle is the only thing left..
On the learning thing for the ecm. You can turn on things that will allow the pcm full control to tune itself. That is IF all your sensors are working like they should and there are no physical issues with your vehicle.
Last edited by trever1t; 12-10-2008 at 03:32 PM.
01-12-2009, 08:35 PM
#20
My idle is pretty good, my problem is cold start up. When i first start up (mostly when its cold outside more so than when its not) it doesnt want to come "up to speed"....it will just sort of buck a little and not fire right up. If i shut it down immediately then immediately fire it back up....it fires right up no problem. I didnt want to hijack this thread, but it looked like it had died off but your advise was intriging as i have never really understood idle tuning at all. The issue i have is the problem is almost impossible to monitor because it only lasts for about 10 seconds and it only happens on the first cold start. What do you think?