More idle table questions (answer and win a smiley)

[QUICKSILVER2002]

I have a slightly annoying idle problem from time to time and I want to finally understand how all the idle tables work.

I think most of my confusion is caused by the adaptive idle routines (I sure hope someone put PIDS for this in the scanner soon, hint hint hint... we could really use this)

Ok, so is it true that the adaptive idle routines stop working when the throttle cracker is enabled {B4311}? I've read somewhere that the long term idle correction is still in effect, but I'm just not sure.

Also, what does {B0107},{B0108} really do. (Max TP/Speed for idle mode) The documentation says all airflow calcs will be done in non-idle if conditions are above these parameter values. I think these values are both 0 from the factory, so it is pretty confusing. I think idle is the most confusing term when it comes to tuning an ls1. It is used all over the place, but means many different things.

I still don't have a clear understanding of the IAP table. Can anyone explain how it works under the covers? I've heard vary conflicting info about this table. The stock values are also pretty crazy (19 g/s with a 104*F/40*C IAT). Is parked all the way open? So is it the amount of airflow based on {B2201} - Default IAC parked Position (usually 310/320 steps). That would make sense, but how is it used (if at all).

I have a final question about the idle fuel trim cells 19... (What triggers those cells?). Is there something that says x TP% and RPM = idle FTC... Is there a parameter somewhere? The other FTCs are easy to see in the RPM and MAP boundaries, but the idle thing has always thrown me off.

It is amazing how complex something as simple as idle is. All the other tuning seems so simple to me, but this stuff is tricky.

[Dirk Diggler]

I am with you on idle giving me the most problems but i think i have figured most of it out hopefully

[SSpdDmon]

I have a final question about the idle fuel trim cells 19... (What triggers those cells?). Is there something that says x TP% and RPM = idle FTC... Is there a parameter somewhere? The other FTCs are easy to see in the RPM and MAP boundaries, but the idle thing has always thrown me off.

I think I remember seeing this part in the Engine>Fuel>Trim>Parameters menu. Can't be sure though...at work right now.

[QUICKSILVER2002]

I have a final question about the idle fuel trim cells 19... (What triggers those cells?). Is there something that says x TP% and RPM = idle FTC... Is there a parameter somewhere? The other FTCs are easy to see in the RPM and MAP boundaries, but the idle thing has always thrown me off.

I think I remember seeing this part in the Engine>Fuel>Trim>Parameters menu. Can't be sure though...at work right now.

There is {B4103 - closed loop idle TP} in the 02 section, but I think that is just related to how the STFT work at idle.

[QUICKSILVER2002]

Ok, still no answers. I've been trying some things and so far I have concluded that the IAP table does nothing while the car is stitting at idle If someone has had other results and can explain that would be great.

The car did seem to run a bit worse on trasitions as I played with the table, but nothing was clear.

[bink]

Ok, still no answers. I've been trying some things and so far I have concluded that the IAP table does nothing while the car is stitting at idle If someone has had other results and can explain that would be great.

The car did seem to run a bit worse on trasitions as I played with the table, but nothing was clear.

IAP- The amount of air the IAC flows maximally for a given IAT range (310 steps for me).
Increasing the IAP value indicates more airflow and thus PCM will reduce in it's compensation. Like IFR table.

The closer the IAP/IAC values are to MAF/Dynamic Airflow the better idle and idle transitions will be (as a consequence idle spark also). A "good" VE table is critical.

There is an IAC/IAP value that is added to the Idle routine.

FWIW.

[QUICKSILVER2002]

Ok, still no answers. I've been trying some things and so far I have concluded that the IAP table does nothing while the car is stitting at idle If someone has had other results and can explain that would be great.

The car did seem to run a bit worse on trasitions as I played with the table, but nothing was clear.

IAP- The amount of air the IAC flows maximally for a given IAT range (310 steps for me).
Increasing the IAP value indicates more airflow and thus PCM will reduce in it's compensation. Like IFR table.

The closer the IAP/IAC values are to MAF/Dynamic Airflow the better idle and idle transitions will be (as a consequence idle spark also). A "good" VE table is critical.

There is an IAC/IAP value that is added to the Idle routine.

FWIW.

Bink, this is the best info that I have seen so far. You win the smiley. :) :) :)

So the table defines the amount of airflow at the default parked position of the IAC (310 steps for me also). I suspected this, but was not sure.

I’m still a little confused about some of your statements. When you refer to “IAC” do you mean the IAC effective area table, dle Air Control in general, or the Idle Airflow(RAF) table?

I’m trying to understand what increasing/decreasing the value would do with all other things being constant and close to realistic. What should happen if I raise the IAP? You mention that it will reduce its compensation. So does this mean that the desired IAC airflow will reduce overall?

You also mention, "There is an IAC/IAP value that is added to the Idle routine". Do you literally mean IAC divided by IAP. If so, what is IAC. Sorry for being so confused, but all these acronyms are throwing me off.

Again, I think all the confusion surrounds the adaptive stuff that we cannot see with EFI Live. I change the table and see no running impact in my scans, but that is most likely because the adaptive stuff is taking over and covering up my changes in the majority of conditions.

[hpcubed]

While we are on the subject, the corvette has no IAC valve, so what are those values controlling?

[QUICKSILVER2002]

The idle routines come up with a desired airflow. This is then traslated to mm squared. This value is then sent to the Electronic Throttle Contol routines on corvettes (IAC motor routines on F-bodies...). The effective area table is used on cars with an IAC to convert the area into IAC steps. ETC has a single value conversion from area to TP.

I got most of the above info from a collection of info I have been collecting from different posts. I think it came from someone at HP tuners.

[hpcubed]

The idle routines come up with a desired airflow. This is then traslated to mm squared. This value is then sent to the Electronic Throttle Contol routines on corvettes (IAC motor routines on F-bodies...). The effective area table is used on cars with an IAC to convert the area into IAC steps. ETC has a single value conversion from area to TP.

I got most of the above info from a collection of info I have been collecting from different posts. I think it came from someone at HP tuners.

Ok, I am still a bit confused. First, from your above statement, it would seem that the IAC effective area table is not used on corvettes since there is no IAC motor to step?

Second, how does the idle airflow effect the idle speed (or quality). You can set the desired idle speed to a certain value, the computer tries to maintain that idle speed. I have changed the idle air control values in the bi-directional controls and did not see any effect on idle quality or rpm. Is the idle air flow (or idle air control) doing anything on a corvette?

[QUICKSILVER2002]

Ok, I am still a bit confused. First, from your above statement, it would seem that the IAC effective area table is not used on corvettes since there is no IAC motor to step?

Second, how does the idle airflow effect the idle speed (or quality). You can set the desired idle speed to a certain value, the computer tries to maintain that idle speed. I have changed the idle air control values in the bi-directional controls and did not see any effect on idle quality or rpm. Is
the idle air flow (or idle air control) doing anything on a corvette?


Right, the IAC effective area is not used on corvettes (from what I can tell - but I have not verified this).

Bi-directional does not work on the corvette because there is no IAC motor to control. It would work if it changed the desired airflow inside the PCM code, but it does not seem to work that way. It just sends/overrides the IAC value directly to the IAC part of the code (which does nothing on the corvette).

Idle airflow still has a big impact on idle quality, speed... but it just uses the Electronic throttle blade instead of an IAC motor/stepper. So the part of the code that deals with IAC steps is not active on corvettes, but all the other idle air related stuff that comes up with the desired airflow values is still used and is critical to idle quality.

I have found it to be very tricky to work with. Mainly because there are all these idle air trims that modify the desired idle airflow in a closed loop fashion to hit the targeted RPM. So, it is very hard to see the impact of the changes you make to the idle tables. The trims only work up to a point and that is why you can often get oddball behavior on idle transitions. Again, its unclear as to when the trims are actually working.

I would encourage everyone to ask the EFI-Live folks to get the idle airflow trims into the scanner ASAP. I’m not sure if it will clear up everything, but it sure seems like it would help those of us with strange idle problems.

[bink]

Effective Area does apply to Corvettes. There is a conversion to TPS%.

BiDi control does work with ETC - at least V6 BiDi worked with mine.

There are Learned Idle Airflow values retained in RAM. Pull both PCM fuses for greater than 3 minutes to erase. Flashing a tune does not erase these values. FWIW.

Cheers,
joel

[bink]

Ok, still no answers. I've been trying some things and so far I have concluded that the IAP table does nothing while the car is stitting at idle If someone has had other results and can explain that would be great.

The car did seem to run a bit worse on trasitions as I played with the table, but nothing was clear.

IAP- The amount of air the IAC flows maximally for a given IAT range (310 steps for me).
Increasing the IAP value indicates more airflow and thus PCM will reduce in it's compensation. Like IFR table.

The closer the IAP/IAC values are to MAF/Dynamic Airflow the better idle and idle transitions will be (as a consequence idle spark also). A "good" VE table is critical.

There is an IAC/IAP value that is added to the Idle routine.

FWIW.

Bink, this is the best info that I have seen so far. You win the smiley. :) :) :)

So the table defines the amount of airflow at the default parked position of the IAC (310 steps for me also). I suspected this, but was not sure.

I’m still a little confused about some of your statements. When you refer to “IAC” do you mean the IAC effective area table, dle Air Control in general, or the Idle Airflow(RAF) table?

I’m trying to understand what increasing/decreasing the value would do with all other things being constant and close to realistic. What should happen if I raise the IAP? You mention that it will reduce its compensation. So does this mean that the desired IAC airflow will reduce overall?

You also mention, "There is an IAC/IAP value that is added to the Idle routine". Do you literally mean IAC divided by IAP. If so, what is IAC. Sorry for being so confused, but all these acronyms are throwing me off.

Again, I think all the confusion surrounds the adaptive stuff that we cannot see with EFI Live. I change the table and see no running impact in my scans, but that is most likely because the adaptive stuff is taking over and covering up my changes in the majority of conditions.

I'm sorry I missed this.
gojo and Nick Williams deserve the smiley - not me.

IAP - Idle Air Parked.

IAC - since a vette doesn't have a true IAC the IAC is a value related to TPS%. The main point is it is a value which can be scanned and adjusted. The PID for the IAC with ETC is DESIAC (Desired IAC) .There is one PID for Desired IAC steps and one for g/sec. Increasing the Idle Air Parked {B4308} value increases the Desired IAC (DESIAC). See the Idle Tuning Sticky .

There is a maximum amount of idle airflow which is added to the TPS% (see Commercial Version ETC parameters). This can be seen scanning for "ETC IDLE_A" and "ETCIDLE_B". These are Desired Idle AirFlow with and without Idle contribution. My point here is the IAP (4308) is important in idle transitioning - contrary to many statements that it only positions the blade when the ignition is off.

I agree once the adaptive idle routines are available this will seem much easier.


Cheers,
joel

[QUICKSILVER2002]

Effective Area does apply to Corvettes. There is a conversion to TPS%.

BiDi control does work with ETC - at least V6 BiDi worked with mine.

There are Learned Idle Airflow values retained in RAM. Pull both PCM fuses for greater than 3 minutes to erase. Flashing a tune does not erase these values. FWIW.

Cheers,
joel

So it converts mm sq to steps and then steps into TPS%. I had heard that it went directly from mm sq to tps%, but I can't find any more info on that.

I can't seem to get BiDi to work with the IAC on a corvette. Everything seems to stay the same as I change values (again, I've only tired this while sitting at idle and the trims may be fooling with me).

I'll be trying some more things this weekend and will report back.

I'll have to remember to pull the fuses/batt. I think that would help clarify a few things.

[QUICKSILVER2002]

I did some more playing around today. Bi-directional control of the IAC/ETC does not seem to work on my car. I’m running 7.2.2 build 236 and the car is a 2002 c5 with the stock os.

Not sure what is going on, but nothing changes as I move the values(ETC or IAC) up and down. All the other stuff RPM, Spark.. work.

I did however seem to get lucky with some of the changes I tried. I decided to increase the idle learn limits and see what that would do. I had read a post in the idle transition thread where someone said this resolved a problem for them.

I set:
Idle learn drive High/low to 4.0,-4.0
Idle learn drive A/C High/low to 1.5,-1.5
ETC Max Idle Contribution to 4.0
(these were all increases to the stock values)

I then set my IAP.. tables back to where they were before I started trying crazy stuff. I disconnected the batt for 10 minutes.

The idle transitions are great now. I'm not sure why, the data I logged looks the same, but the behavior seems to be totally different. I'm not going to declare victory yet though, I have had it work this well before and then it would eventually learn its way back to running like crap. I hope that does not happen this time.

[bink]

QUICKSILVER2002 -What are your mods?

Cheers,
joel

[QUICKSILVER2002]

QUICKSILVER2002 -What are your mods?

Cheers,
joel

Pretty much everything
+ a blower. It is 650-700RWHP setup. The cam is pretty mild though 224ish on 115. The blower also probably puts a slight load on the crank at idle.

I think I may have figured out one additional thing that is screwing up my idle learns... I have a high speed fan override switch that I operate from the ash tray area. I often flip it on when I plan on running the car hard (it helps bring my IAT and ETC down at low speeds since my intercooler sits in front of the radiator). I think this may cause some issues for the idle learn. The PCM does not realize the high speed fans are on, yet the added load from the alternator is there. Then I flip the switch off and it has learned too much air...

I'm going to stop using that switch (on the street) and just program the fans on a little earlier. The car ran good all day yesterday, but I did get a stumble and a misfire code set right when I flipped that switch on. You would think that it would adjust for it pretty quickly, but it seems like the short term idle trims are pretty slow to react. Again, I sure wish we could scan that stuff.

I’m going to send a PM to Paul now and try to find out when those will show up.