Idle transition tuning
01-27-2005, 01:39 PM
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Idle transition tuning Idle (transition) tuning procedure for C5's (drive by wire).
A collaborative effort between Nick Williams and myself. A lot of testing on many cars has been done to ensure the process works. Besides it makes sense. There are pieces of information that have been stated by others, but seem to have been somewhat ignored. The MAPS in EFI have helped make the tuning process easier. We are very open to ideas,or the need for clarity. You can prove the process by logging the information suggested, from a stock car and you will see the results make sense.
The following assumes a reasonable tune has been done to the car. Here is a quick outline of my preferred method.
-Put back all stock airflow and timing values.
-Input the stock IFR values for stock injectors, or calculate new values for larger ones.
-Put in A/F multiplier values(PE RPM), calculated to your preference. (ex.14.7/12.8 = 1.15 mult.)
-Work on VE's with the MAF zeroed. (You can do speed density. I just don't feel it's worthwhile if you run an MAF. JMO. Others can do what's right for them.) Bring the MAF back on line and adjust it for ltrims.
-Then do Idle Transition Tuning.
Idle transition tuning:
-Start with Ltrims reasonably negative and your Standing Idle is set where you are happy with it at all temps.
-If your VE's are off by 20% or more they need to be set.
-Return all airflow tables to stock, except idle, idle airflow parked(IAC Park) and idle airflow(RAF). This is so the car will idle. If you can return all the airflow tables to stock, go ahead.
-Set up Maps for Maf gms/s and Desiac gms/s, by ECT. Use the format in the PCM.
-Log, IATc, ECTc, SAE MAF gms/s, GM DESIAC gms/s.
Since you are in open loop when you first start the car, watch for your trims to show(closed loop) and your idle to settle to where it's set and start the tuning log.
Log while parked, from the coldest engine temperature to fully warmed.
Log for at least five minutes after warm up to get better averages and since this is the temperarture where problems are noticed.
-If it's an a4, log in gear with the A/C on. You may want to repeat this process in neutral later or just check to see if your RPM's stay up when driving and you put the car in neutral.
-If it's an M6 log in neutral.
-Input the logged MAF values into the idle airflow (raf) table, by temperature.
-Raise or lower idle airflow parked (IAC park ) values.
You want to match logged desiac and maf values.
This is done within each IAT range. You will need to watch Desiac and Maf results in Dash f10.
Raising/lowering IAP raises/lowers desiac.
The idle airflow parked table is the difficult part for a number of reasons.
-The temperatures are IAT. Some think they are ECT.
-The temperature scale is in 20c increments.
-Raising the IAP values raises logged desiac, and raises expected airflow. The TB closes some and you could get stalling surging, etc., if your target is wrong. The opposite scenerio would be racing. This is important, since you are working with logged averages and may/probably need to make small adjustments and the affect is counter intuitive.
-This need to be done on different days in order to set within each IAT range as weather changes push your intake temperatures up or down.
-Finally, timing will help idle and flare at start up. If you have EFI Pro you
can use BI-D Controls to test(SOP)timing changes, otherwise program
timing changes a little at a time. Make the changes in Base Spark in
Gear and Base Spark in Park/Neutral.
-Check, ltrims, AFR and adjust.
-When you change IFR's, MAF #'s, timing and airflow table values, the
trims are affected
This process will help eliminate, stalling, surging, false idle learn and unlearn, colds, headaches, etc. My opinion is that many of the problems that occur after a cam are a result of not understanding the IAP table. You will notice that your ltrims and strims become flatter.
There are some situations that make perfection a little harder.(Maybe impossible). Don't have knowledge past a G5X3.
-Really big cam. ex. Mine is a 228/589/112 in an a4 and tuning is easy.
-Long tubes that place the 02 sensors far back, which allow them to cool fast and take longer to heat up.
-Cold air intake, which causes rapid IAT changes.
-Any throttle body with a ridge that's been worked.*
-Descreened MAF/ not properly calibrated.
-Low rear gears(3.73 and lower) and a stock or almost stock stall converter.
-The tuners ability.
* I continually read opinions that the 90mm TB is hard to tune. The N. Williams 90mm TB and stock TB's are not hard to tune. It's the cam.
Don't look for perfection in the numbers, they do bounce around. If after you do this it idles and transitions well, be happy.
A collaborative effort between Nick Williams and myself. A lot of testing on many cars has been done to ensure the process works. Besides it makes sense. There are pieces of information that have been stated by others, but seem to have been somewhat ignored. The MAPS in EFI have helped make the tuning process easier. We are very open to ideas,or the need for clarity. You can prove the process by logging the information suggested, from a stock car and you will see the results make sense.
The following assumes a reasonable tune has been done to the car. Here is a quick outline of my preferred method.
-Put back all stock airflow and timing values.
-Input the stock IFR values for stock injectors, or calculate new values for larger ones.
-Put in A/F multiplier values(PE RPM), calculated to your preference. (ex.14.7/12.8 = 1.15 mult.)
-Work on VE's with the MAF zeroed. (You can do speed density. I just don't feel it's worthwhile if you run an MAF. JMO. Others can do what's right for them.) Bring the MAF back on line and adjust it for ltrims.
-Then do Idle Transition Tuning.
Idle transition tuning:
-Start with Ltrims reasonably negative and your Standing Idle is set where you are happy with it at all temps.
-If your VE's are off by 20% or more they need to be set.
-Return all airflow tables to stock, except idle, idle airflow parked(IAC Park) and idle airflow(RAF). This is so the car will idle. If you can return all the airflow tables to stock, go ahead.
-Set up Maps for Maf gms/s and Desiac gms/s, by ECT. Use the format in the PCM.
-Log, IATc, ECTc, SAE MAF gms/s, GM DESIAC gms/s.
Since you are in open loop when you first start the car, watch for your trims to show(closed loop) and your idle to settle to where it's set and start the tuning log.
Log while parked, from the coldest engine temperature to fully warmed.
Log for at least five minutes after warm up to get better averages and since this is the temperarture where problems are noticed.
-If it's an a4, log in gear with the A/C on. You may want to repeat this process in neutral later or just check to see if your RPM's stay up when driving and you put the car in neutral.
-If it's an M6 log in neutral.
-Input the logged MAF values into the idle airflow (raf) table, by temperature.
-Raise or lower idle airflow parked (IAC park ) values.
You want to match logged desiac and maf values.
This is done within each IAT range. You will need to watch Desiac and Maf results in Dash f10.
Raising/lowering IAP raises/lowers desiac.
The idle airflow parked table is the difficult part for a number of reasons.
-The temperatures are IAT. Some think they are ECT.
-The temperature scale is in 20c increments.
-Raising the IAP values raises logged desiac, and raises expected airflow. The TB closes some and you could get stalling surging, etc., if your target is wrong. The opposite scenerio would be racing. This is important, since you are working with logged averages and may/probably need to make small adjustments and the affect is counter intuitive.
-This need to be done on different days in order to set within each IAT range as weather changes push your intake temperatures up or down.
-Finally, timing will help idle and flare at start up. If you have EFI Pro you
can use BI-D Controls to test(SOP)timing changes, otherwise program
timing changes a little at a time. Make the changes in Base Spark in
Gear and Base Spark in Park/Neutral.
-Check, ltrims, AFR and adjust.
-When you change IFR's, MAF #'s, timing and airflow table values, the
trims are affected
This process will help eliminate, stalling, surging, false idle learn and unlearn, colds, headaches, etc. My opinion is that many of the problems that occur after a cam are a result of not understanding the IAP table. You will notice that your ltrims and strims become flatter.
There are some situations that make perfection a little harder.(Maybe impossible). Don't have knowledge past a G5X3.
-Really big cam. ex. Mine is a 228/589/112 in an a4 and tuning is easy.
-Long tubes that place the 02 sensors far back, which allow them to cool fast and take longer to heat up.
-Cold air intake, which causes rapid IAT changes.
-Any throttle body with a ridge that's been worked.*
-Descreened MAF/ not properly calibrated.
-Low rear gears(3.73 and lower) and a stock or almost stock stall converter.
-The tuners ability.
* I continually read opinions that the 90mm TB is hard to tune. The N. Williams 90mm TB and stock TB's are not hard to tune. It's the cam.
Don't look for perfection in the numbers, they do bounce around. If after you do this it idles and transitions well, be happy.
Last edited by gojo; 02-15-2005 at 12:17 PM.
01-27-2005, 08:55 PM
#2
This should be a sticky!! 
I don't understand why there hasn't been much response?This was posted over 7 hrs. ago?
Guys, the airflow values set from these tables effects your Tune globally.
If these are right, along with the VE as gojo states, most of the surging, bucking and hanging are eliminated.
This is as "cookbook" as you can get.
Thanks gojo and Nick!!
I don't understand why there hasn't been much response?This was posted over 7 hrs. ago?
Guys, the airflow values set from these tables effects your Tune globally.
If these are right, along with the VE as gojo states, most of the surging, bucking and hanging are eliminated.
This is as "cookbook" as you can get.
Thanks gojo and Nick!!
01-27-2005, 09:08 PM
#3
Originally Posted by Bink
This should be a sticky!!
I don't understand why there hasn't been much response?This was posted over 7 hrs. ago?
Guys, the airflow values set from these tables effects your Tune globally.
If these are right, along with the VE as gojo states, most of the surging, bucking and hanging are eliminated.
This is as "cookbook" as you can get.
Thanks gojo and Nick!!
I don't understand why there hasn't been much response?This was posted over 7 hrs. ago?
Guys, the airflow values set from these tables effects your Tune globally.
If these are right, along with the VE as gojo states, most of the surging, bucking and hanging are eliminated.
This is as "cookbook" as you can get.
Thanks gojo and Nick!!
01-27-2005, 10:14 PM
#4
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Originally Posted by Bink
This should be a sticky!!
I don't understand why there hasn't been much response?This was posted over 7 hrs. ago?
Guys, the airflow values set from these tables effects your Tune globally.
If these are right, along with the VE as gojo states, most of the surging, bucking and hanging are eliminated.
This is as "cookbook" as you can get.
Thanks gojo and Nick!!
I don't understand why there hasn't been much response?This was posted over 7 hrs. ago?
Guys, the airflow values set from these tables effects your Tune globally.
If these are right, along with the VE as gojo states, most of the surging, bucking and hanging are eliminated.
This is as "cookbook" as you can get.
Thanks gojo and Nick!!
01-27-2005, 10:54 PM
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What is dashF10
What is IAP
-Raise or lower idle airflow parked (IAC park ) values.
You want to match logged desiac and maf values.
This is done within each IAT range. You will need to watch Desiac and Maf results in Dash f10.
Raising/lowering IAP raises/lowers desiac
What is IAP
-Raise or lower idle airflow parked (IAC park ) values.
You want to match logged desiac and maf values.
This is done within each IAT range. You will need to watch Desiac and Maf results in Dash f10.
Raising/lowering IAP raises/lowers desiac
Last edited by Closer_2001; 01-28-2005 at 12:00 AM.
01-28-2005, 11:22 AM
#7
Originally Posted by Closer_2001
What is dashF10
What is IAP
-Raise or lower idle airflow parked (IAC park ) values.
You want to match logged desiac and maf values.
This is done within each IAT range. You will need to watch Desiac and Maf results in Dash f10.
Raising/lowering IAP raises/lowers desiac
What is IAP
-Raise or lower idle airflow parked (IAC park ) values.
You want to match logged desiac and maf values.
This is done within each IAT range. You will need to watch Desiac and Maf results in Dash f10.
Raising/lowering IAP raises/lowers desiac
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01-28-2005, 11:27 AM
#8
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Originally Posted by Closer_2001
What is dashF10
What is IAP
-Raise or lower idle airflow parked (IAC park ) values.
You want to match logged desiac and maf values.
This is done within each IAT range. You will need to watch Desiac and Maf results in Dash f10.
Raising/lowering IAP raises/lowers desiac
What is IAP
-Raise or lower idle airflow parked (IAC park ) values.
You want to match logged desiac and maf values.
This is done within each IAT range. You will need to watch Desiac and Maf results in Dash f10.
Raising/lowering IAP raises/lowers desiac
With EFI V7, Maps(pivot tables?) can be created. Dash F10 references which dash to watch in EFI. With other scanners just watch your logging or export to Excel.
BTW, I've had a couple of emails and the reply addresses were rejected.
02-02-2005, 12:07 PM
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Originally Posted by gojo
Closer, I use EFI so I probably have HPT's terminology wrong. Hopefully we will get HPT users helping. I cross referenced Edit above. I am familiar with it.
With EFI V7, Maps(pivot tables?) can be created. Dash F10 references which dash to watch in EFI. With other scanners just watch your logging or export to Excel.
BTW, I've had a couple of emails and the reply addresses were rejected.
With EFI V7, Maps(pivot tables?) can be created. Dash F10 references which dash to watch in EFI. With other scanners just watch your logging or export to Excel.
BTW, I've had a couple of emails and the reply addresses were rejected.
Here it is.
02-02-2005, 04:46 PM
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You can also try using the new idle MPIDs we added in 1.6.0 i think they will remove a lot of steps from the process Imho, they are much more useful for tuning than the spark PIDs everyone is making a lot of noise about during the "who's catching up to who" threads 
Not to mention VCM Editor now includes just about *every* idle parameter in the PCM, and the help file has some info there too.
Long Term and Short Term Idle trims are where the action is, and also boundary checking the adaptive limits removes any mystery about idle transitions.
New Idle Airflow MPIDs (vehicle dependant):
- Startup Airflow
- Throttle Cracker Airflow
- Throttle Follower Airflow
- Fans Airflow
- Startup Retard Airflow
- AC Airflow
- Base In Gear Airflow
- Long Term Idle Trim Airflow In Gear
- Base PN Airflow
- Long Term Idle Trim Airflow PN
- Short Term Idle Trim Airflow
- Park Position Airflow
Imho, they are much more useful for tuning than the spark PIDs everyone is making a lot of noise about during the "who's catching up to who" threads Not to mention VCM Editor now includes just about *every* idle parameter in the PCM, and the help file has some info there too.
Long Term and Short Term Idle trims are where the action is, and also boundary checking the adaptive limits removes any mystery about idle transitions.
New Idle Airflow MPIDs (vehicle dependant):
- Startup Airflow
- Throttle Cracker Airflow
- Throttle Follower Airflow
- Fans Airflow
- Startup Retard Airflow
- AC Airflow
- Base In Gear Airflow
- Long Term Idle Trim Airflow In Gear
- Base PN Airflow
- Long Term Idle Trim Airflow PN
- Short Term Idle Trim Airflow
- Park Position Airflow
05-03-2005, 01:28 PM
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Originally Posted by gameover
You can also try using the new idle MPIDs we added in 1.6.0 i think they will remove a lot of steps from the process Imho, they are much more useful for tuning than the spark PIDs everyone is making a lot of noise about during the "who's catching up to who" threads
Not to mention VCM Editor now includes just about *every* idle parameter in the PCM, and the help file has some info there too.
Long Term and Short Term Idle trims are where the action is, and also boundary checking the adaptive limits removes any mystery about idle transitions.
New Idle Airflow MPIDs (vehicle dependant):
- Startup Airflow
- Throttle Cracker Airflow
- Throttle Follower Airflow
- Fans Airflow
- Startup Retard Airflow
- AC Airflow
- Base In Gear Airflow
- Long Term Idle Trim Airflow In Gear
- Base PN Airflow
- Long Term Idle Trim Airflow PN
- Short Term Idle Trim Airflow
- Park Position Airflow
Imho, they are much more useful for tuning than the spark PIDs everyone is making a lot of noise about during the "who's catching up to who" threads Not to mention VCM Editor now includes just about *every* idle parameter in the PCM, and the help file has some info there too.
Long Term and Short Term Idle trims are where the action is, and also boundary checking the adaptive limits removes any mystery about idle transitions.
New Idle Airflow MPIDs (vehicle dependant):
- Startup Airflow
- Throttle Cracker Airflow
- Throttle Follower Airflow
- Fans Airflow
- Startup Retard Airflow
- AC Airflow
- Base In Gear Airflow
- Long Term Idle Trim Airflow In Gear
- Base PN Airflow
- Long Term Idle Trim Airflow PN
- Short Term Idle Trim Airflow
- Park Position Airflow
05-04-2005, 02:01 AM
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Originally Posted by SuperC1
Any info on exactly what changes should/should not be made on the adaptive idle limits?
05-04-2005, 04:29 AM
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the help file contains the info however here's what you can do.
Monitor your two LTIT's and STIT in the scanner. You will notice the LTIT should settle to a constant value after a few minutes (idle learn process) in PN and Gear for A4's and Gear for M6's. After the LTITs have settled take note of the following:
- the LTITs should be within the min/max limits shown in the editor (see the help file)
- the STIT should be close to 0
If the LTIT's are at either the min or max limit you have a problem with your base running airflow (if LTIT is max and the STIT is positive then your base running airflow is too low, if LTIT is min and the STIT is negative base running airflow is too high). Also it's good to watch your STIT when the fans come on so you can see if the correction is ok.
I tend to keep the limits at the factory settings and just change the base running airflow numbers and the various compensation factors.
The important thing to remember is the base running airflow is the starting point for the adpative idle routines. Most cruise control and rpm drop issues when coming to a stop are symptoms of the LTITs being at their limits due to base running airflow being out to much. This is most noticeable after a camshaft change.
Chris...
Monitor your two LTIT's and STIT in the scanner. You will notice the LTIT should settle to a constant value after a few minutes (idle learn process) in PN and Gear for A4's and Gear for M6's. After the LTITs have settled take note of the following:
- the LTITs should be within the min/max limits shown in the editor (see the help file)
- the STIT should be close to 0
If the LTIT's are at either the min or max limit you have a problem with your base running airflow (if LTIT is max and the STIT is positive then your base running airflow is too low, if LTIT is min and the STIT is negative base running airflow is too high). Also it's good to watch your STIT when the fans come on so you can see if the correction is ok.
I tend to keep the limits at the factory settings and just change the base running airflow numbers and the various compensation factors.
The important thing to remember is the base running airflow is the starting point for the adpative idle routines. Most cruise control and rpm drop issues when coming to a stop are symptoms of the LTITs being at their limits due to base running airflow being out to much. This is most noticeable after a camshaft change.
Chris...
05-04-2005, 12:34 PM
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Originally Posted by gameover
the help file contains the info however here's what you can do.
Monitor your two LTIT's and STIT in the scanner. You will notice the LTIT should settle to a constant value after a few minutes (idle learn process) in PN and Gear for A4's and Gear for M6's. After the LTITs have settled take note of the following:
- the LTITs should be within the min/max limits shown in the editor (see the help file)
- the STIT should be close to 0
If the LTIT's are at either the min or max limit you have a problem with your base running airflow (if LTIT is max and the STIT is positive then your base running airflow is too low, if LTIT is min and the STIT is negative base running airflow is too high). Also it's good to watch your STIT when the fans come on so you can see if the correction is ok.
I tend to keep the limits at the factory settings and just change the base running airflow numbers and the various compensation factors.
The important thing to remember is the base running airflow is the starting point for the adpative idle routines. Most cruise control and rpm drop issues when coming to a stop are symptoms of the LTITs being at their limits due to base running airflow being out to much. This is most noticeable after a camshaft change.
Chris...
Monitor your two LTIT's and STIT in the scanner. You will notice the LTIT should settle to a constant value after a few minutes (idle learn process) in PN and Gear for A4's and Gear for M6's. After the LTITs have settled take note of the following:
- the LTITs should be within the min/max limits shown in the editor (see the help file)
- the STIT should be close to 0
If the LTIT's are at either the min or max limit you have a problem with your base running airflow (if LTIT is max and the STIT is positive then your base running airflow is too low, if LTIT is min and the STIT is negative base running airflow is too high). Also it's good to watch your STIT when the fans come on so you can see if the correction is ok.
I tend to keep the limits at the factory settings and just change the base running airflow numbers and the various compensation factors.
The important thing to remember is the base running airflow is the starting point for the adpative idle routines. Most cruise control and rpm drop issues when coming to a stop are symptoms of the LTITs being at their limits due to base running airflow being out to much. This is most noticeable after a camshaft change.
Chris...
Can we elaborate a little?
05-04-2005, 01:07 PM
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I believe he is talking about the Decay in PN & Gear, Delay in PN & Gear, Throttle Follower and Cracker, IAC vs. Effective Area and all those "other" tables in the one little screen.
Chris, thats a bunch for that quick tech tip.
Charlie
Chris, thats a bunch for that quick tech tip.
Charlie
05-04-2005, 06:04 PM
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Originally Posted by SuperC1
Various compensation factors?? Can we elaborate a little?
Can we elaborate a little?There is also the throttle cracker which opens the IAC based on RPM and mph, and the throttle follower which is a dampener/decay function for when you close the throttle suddenly.
The other is the AC. The AC is a little different as it is torque based, you'll need to head over to the Engine -> Torque Management -> Engine Torque section and look at the "AC Compressor Torque" tables. Again, watching your LTIT and STIT when the AC comes on will tell you which way you need to move things.
Chris...
05-11-2005, 07:25 PM
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Originally Posted by gameover
The main one is the "Cooling Fan Airflow" this is the extra IAC airflow required to compensate for the alternator load when either one or both fans are on.
There is also the throttle cracker which opens the IAC based on RPM and mph, and the throttle follower which is a dampener/decay function for when you close the throttle suddenly.
The other is the AC. The AC is a little different as it is torque based, you'll need to head over to the Engine -> Torque Management -> Engine Torque section and look at the "AC Compressor Torque" tables. Again, watching your LTIT and STIT when the AC comes on will tell you which way you need to move things.
Chris...
There is also the throttle cracker which opens the IAC based on RPM and mph, and the throttle follower which is a dampener/decay function for when you close the throttle suddenly.
The other is the AC. The AC is a little different as it is torque based, you'll need to head over to the Engine -> Torque Management -> Engine Torque section and look at the "AC Compressor Torque" tables. Again, watching your LTIT and STIT when the AC comes on will tell you which way you need to move things.
Chris...
Also, why do the FANS require a correction. More load on the alternator should not impact fueling, right? I can see some voltage issues, but that is what injector offset is all about, right? AC makes sense, but electric fans don't.
Maybe this will all be well understood some day.
05-11-2005, 07:44 PM
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The IAC airflows play no part in fueling calculations at all.
The PCM uses "airflow" as it's means of opening the IAC stepper (or ETC). It has no relation at all to fueling calculations at all.
The fan correction is used to provide a more seamless idle RPM transition for the increased alternator load. Rather than just wait for the adaptive idle routines to move. The AC is the same, it only controls the IAC and nothing to do with fueling.
The PCM uses "airflow" as it's means of opening the IAC stepper (or ETC). It has no relation at all to fueling calculations at all.
The fan correction is used to provide a more seamless idle RPM transition for the increased alternator load. Rather than just wait for the adaptive idle routines to move. The AC is the same, it only controls the IAC and nothing to do with fueling.
05-11-2005, 10:44 PM
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Originally Posted by gameover
The IAC airflows play no part in fueling calculations at all.
The PCM uses "airflow" as it's means of opening the IAC stepper (or ETC). It has no relation at all to fueling calculations at all.
The fan correction is used to provide a more seamless idle RPM transition for the increased alternator load. Rather than just wait for the adaptive idle routines to move. The AC is the same, it only controls the IAC and nothing to do with fueling.
The PCM uses "airflow" as it's means of opening the IAC stepper (or ETC). It has no relation at all to fueling calculations at all.
The fan correction is used to provide a more seamless idle RPM transition for the increased alternator load. Rather than just wait for the adaptive idle routines to move. The AC is the same, it only controls the IAC and nothing to do with fueling.
Also, do you think the IAP has impact on the IAC position while the motor is running? There seems to be no clear answer on that one. Some seem to be seeing some results from changing it.