Disabling Proportional Idle

[TAQuickness]

I just received this from a guy at LS1Tech on how to disable your proportional Idle with BrandX

"In [BrandX] it is under Open/Closed Loop Fueling. There is a little button you can click to disable it. It is a different set of values for reacting to the O2 sensors for while your car is at idle"

Can any of you give me an idea of where this is in Flashscan?

[emarkay]

Would make it easier to look for things if [we all] posted what type of car, what model year, and maybe a bit more specifics - I don't recall proportional idle setting, but maybe with ETC it's in there somewhere...

[TAQuickness]

Not sure what difference it makes, but it's a '00 WS6 M6

I'm trying to dial in my LTFT SD tune. Everything is on par except for the idle range. No matter how much I take out of the VE table in the idle range, it still show's I'm running rich. I had leaned out the VE table to the point that I only had 16% as the value's in the idle range and that made the car sputter. I changed those values to 40% and the car idles better.

The only conclusion I could come to is that the PCM does something else during idle forcing it to draw more air in than it needs, or something else that skews the LTFT's.

When I presented this on LS1Tech, I was told to disable the proportional idle so I can dial in the VE table.

Unless someone know's of a better way for me to do this, this is what i'm doing:

SD tune based off LTFT's to dial in the VE table.
Rescale MAF table based off on the VE table being correct.
Idle tune based off VE and MAF tables being correct.

[jfpilla]

It could be something as simple as the RAF values, at warmed up idle, being a little off. I've been surprised at how a small change affects trims.

-Do your desiac g/s, maf g/s and dynair g/s log pretty close to each other?
-Are your trims neg. regardless of IAT while idling?
-How neg. are they at idle?

[TAQuickness]

It could be something as simple as the RAF values, at warmed up idle, being a little off. I've been surprised at how a small change affects trims.

-Do your desiac g/s, maf g/s and dynair g/s log pretty close to each other?
-Are your trims neg. regardless of IAT while idling?
-How neg. are they at idle?

These are my averages (1096 samples) from my last log.
Idle is at MAP 60 kPa & RPM @ 1200
MAF is currently disconected
Idle trims are negative regardless of IAT

average LTFT B1 % = -8.6
average LTFT B2 % = -8.2
average DESIAC = 5.59 g/s
average DYNAIR = 0.24 g/cyl
average RPM = 988.5 RPM
average iat = 14.26 *c
average map = 57.49 kPa

calculated average DYNAIR = 0.0037 g/s using this equation:

Massflow = (VE * MAP * RPM * Displacement) / IAT

Massflow: grams/sec
IAT: Degrees Kelvin
MAP: Bar
RPM: Duh!
Displacement: Cubic Meters
VE: g/cyl

Not sure if the equation is correct. I got it from NoGo at LS1Tech in the sticky "VE Table Cracked" post.


Thanks for the help guys!

[jfpilla]

It could be something as simple as the RAF values, at warmed up idle, being a little off. I've been surprised at how a small change affects trims.

-Do your desiac g/s, maf g/s and dynair g/s log pretty close to each other?
-Are your trims neg. regardless of IAT while idling?
-How neg. are they at idle?

These are my averages (1096 samples) from my last log.
Idle is at MAP 60 kPa & RPM @ 1200
MAF is currently disconected
Idle trims are negative regardless of IAT

average LTFT B1 % = -8.6
average LTFT B2 % = -8.2
average DESIAC = 5.59 g/s
average DYNAIR = 0.24 g/cyl
average RPM = 988.5 RPM
average iat = 14.26 *c
average map = 57.49 kPa

calculated average DYNAIR = 0.0037 g/s using this equation:

Massflow = (VE * MAP * RPM * Displacement) / IAT

Massflow: grams/sec
IAT: Degrees Kelvin
MAP: Bar
RPM: Duh!
Displacement: Cubic Meters
VE: g/cyl

Not sure if the equation is correct. I got it from NoGo at LS1Tech in the sticky "VE Table Cracked" post.


Thanks for the help guys!


Are you using EFI? If you are, you shouldn't have to calculate Dynair.
I have no confidence in my tuning with the MAF disconnected. I've done it, but have not had much luck.

[GMPX]

"In [BrandX] it is under Open/Closed Loop Fueling. There is a little button you can click to disable it. It is a different set of values for reacting to the O2 sensors for while your car is at idle"

Can any of you give me an idea of where this is in Flashscan?

Yes, in Development testing.......it will be out soon, we just need to finalise labels, descriptions, confirmation across all O.S's.

Cheers,
Ross

P.S - You can mention brand 'x', we won't get mad :) , cause there is more than one brand 'x' now.

[TAQuickness]

"In [BrandX] it is under Open/Closed Loop Fueling. There is a little button you can click to disable it. It is a different set of values for reacting to the O2 sensors for while your car is at idle"

Can any of you give me an idea of where this is in Flashscan?

Yes, in Development testing.......it will be out soon, we just need to finalise labels, descriptions, confirmation across all O.S's.

Cheers,
Ross

P.S - You can mention brand 'x', we won't get mad :) , cause there is more than one brand 'x' now.

Brand X is Brand X is Brand X... :lol:

You guys never cease to amaze me! Do you know what the ETA of this new feature hitting the shelves?

I went back into the PID selection and selected the appropriate DYNAIR in g/s and logged 40 miles of data this morning.

Again, these are my averages (3195 samples) @ MAP 60 kPa & RPM 1200:

Average LTFT B1 = -10.6%
Average LTFT B2 = -10.7 %
Average DESIAC = 4.94 G/S
Average DYNAIR = 15.86 G/S
Average IAT = 14.19 *C

MAF is still disconnected. Current BACKUP VE table value @ MAP 60 kPa & RPM 1200 = 44.19

[jfpilla]

Okay, this makes sense to me.
Log the same information, but, in gear for an A4 and in Neutral if M6, standing. Log from cold to totally warmed up. You're lookin to compare Desiac and Dynair and ultimately match those values. When Desiac is right it represents actual airflow at idle. If the VE's are right, matching will flatten the trims so that you can adjust them across the board.
After done and you log, include STFT's. You will get faster feedback on how you're doing.

I tuned mine with MAF zeroed and could see Dynair change with VE changes. It would seem the same thing occurs Mafless. That's why it's important that the VE's are close. If the VE's are too far off so will Dynair and then Desiac will be wrong after matching.

[TAQuickness]

Okay, this makes sense to me.
Log the same information, but, in gear for an A4 and in Neutral if M6, standing. Log from cold to totally warmed up. You're lookin to compare Desiac and Dynair and ultimately match those values. When Desiac is right it represents actual airflow at idle. If the VE's are right, matching will flatten the trims so that you can adjust them across the board.
After done and you log, include STFT's. You will get faster feedback on how you're doing.

I tuned mine with MAF zeroed and could see Dynair change with VE changes. It would seem the same thing occurs Mafless. That's why it's important that the VE's are close. If the VE's are too far off so will Dynair and then Desiac will be wrong after matching.

I'm not sure I follow you 100%. If I understood your correctly, I need to log a cold start to warm idle (in neutral, M6), including LTFT, STFT, Desiac, and Dynair. From the results of this log, I will need to match dynair to desiac?

Not trying to be hard headed here, but sometimes I need someone to spell it out to a T for me so I can grasp the concept. :oops:


I had been adjusting the VE table based on the LTFT'S to get the LTFT's at idle between -4 and 0. I had the VE value as low as 16.something% and my LTFT avg was still -8. When the Ve table value was at 16.x%, the car sputtered like a misfiring 4 banger. The surrounding VE table cells were all in the 40-60 range (from lower kPa to higher or left to right).

When I presented this on LS1Tech, Another_User suggested the proportional idle was helping to skew my LTFT's at Idle.

[jfpilla]

"I'm not sure I follow you 100%. If I understood your correctly, I need to log a cold start to warm idle (in neutral, M6), including LTFT, STFT, Desiac, and Dynair. From the results of this log, I will need to match dynair to desiac? "

Anytime you adjust any of the airflow tables you affect the trims also.
What could be happening in your case, is that the aiflow at idle might be a little high. If that's the case, when you match Dynair and Iacdes, you should see your trims go closer to 0. Are you getting any idle hanging or surging, at all?

"I had been adjusting the VE table based on the LTFT'S to get the LTFT's at idle between -4 and 0. I had the VE value as low as 16.something% and my LTFT avg was still -8. When the Ve table value was at 16.x%, the car sputtered like a misfiring 4 banger. The surrounding VE table cells were all in the 40-60 range (from lower kPa to higher or left to right)."

I had the same problems mafless and decided to just do it by zeroing the MAF and not try for perfection.

"When I presented this on LS1Tech, Another_User suggested the
proportional idle was helping to skew my LTFT's at Idle."

When Nick and I developed the tuning procedure I described in Idle Transition Tuning, we found that we could return all the airflow tables to stock. The only table we have used on both f-bodies and C5's are, idle airflow, idle airflow parked, VE, MAF and timing. I'm guessing, but it seems that if these tables are right then the remaining tables are in correct proportions.

If you want to see my logs send me your e-mail address.

[TAQuickness]

The only undesired idle trait at the moment is dip's. Seems like when I return to idle coming off a load (no problem if i just sit in the drive way and rev it), it will dip and occasionally die. if it doesn't die, it hunts for about 10-30 seconds, finds the idle then everything is smooth.

My VE table is just about dead on, except for idle and 2 or 3 other cells. I was thinking to call it good enough, dial in the MAF table (GM 85mm MAF should be here today), then proceed with the idle transistion tuning you wrote.

I'll get back to this in about a week. The car is going back in the air tonight for the 12 bolt and 373's...

[jfpilla]

The only undesired idle trait at the moment is dip's. Seems like when I return to idle coming off a load (no problem if i just sit in the drive way and rev it), it will dip and occasionally die. if it doesn't die, it hunts for about 10-30 seconds, finds the idle then everything is smooth.

My VE table is just about dead on, except for idle and 2 or 3 other cells. I was thinking to call it good enough, dial in the MAF table (GM 85mm MAF should be here today), then proceed with the idle transistion tuning you wrote.

I'll get back to this in about a week. The car is going back in the air tonight for the 12 bolt and 373's...

The hunting is a good indicator that the Airflow Park and Idle Airflow need to be adjusted. I think you will be pleasantly surprised.
Good luck with the gears. I love low gears, they really transform a car.. My first car had a 4:11. A 55' chevy.

[Dirk Diggler]

Thanks GMPX I LOVE NEW FEATURES

[TAQuickness]

The hunting is a good indicator that the Airflow Park and Idle Airflow need to be adjusted. I think you will be pleasantly surprised.
Good luck with the gears. I love low gears, they really transform a car.. My first car had a 4:11. A 55' chevy.

I decided to hold off on the 12 bolt install until I get the tune worked out (I'm so close I can taste it!)

Any how, I logged a cold start and was watching a modified dash to see how the IACDES_B and DYNAIR compared, both in g/s.

Seems the DYNAIR likes to be right at 20 g/s, regardless of temp, and the IACDES_B on initial start up is ~20 g/s then starts to drop off (over the course of 1 minute) to ~5 g/s. While both are around 20 g/s, the car purs like a kitten. But, as soon as the IACDES_B drops down to about 16 g/s, the idle gets rough.

I have not reduced my VE table in the idle range any further. My LTFT's in the idle range are still ~ -10 - everything else is between -2 and 0.5.

For the time being, the MAF will remain disconnected (waiting on a new stocker to show up).

So, where do I start. Do I need to adjust the VE table so my DYNAIR matches IACDES_B, or do I need to adjust the idle tables so IACDES_B matches DYNAIR?

[jfpilla]

(Average DYNAIR = 15.86 G/S) This was your avg. the last time you logged and now it is at 20C regardless of ECT? That makes no sense.
You should be inputting to the idle airflow table, the dynair values, by ECT. There is no point to putting in 20C across the board.
If you want, send me your PCM file and EFI log to: jfpilla @triad.rr.com.

[TAQuickness]

It's gonna take me a while. On the log home last night, My left bank LTFT's shot way positive while the right bank looked perfect. As soon as I find the problem and get it fixed, I'll send you the log and tune.

I appreciate you help

[TAQuickness]

Found the problem... 4 of the left bank header bolts had come loose.

Back to the tuning.

I stopped by a buddies house last night and logged a cold start to warm Idle on his '99 SS. It makes perfect sense now why my car idles like crap. His dynamic air vs desired air tracks each other within < 1 g/s where as mine is off by by ~ 11 g/s (dynamic over desired).

Buddy's Car:

40 kPa @ 1200 RPM
AVG DES Air = 7.3 g/s
AVG Dyn Air = 7.1 g/s

My Car:
70 kPa @ 1200 RPM
AVG DES Air = 6.1 g/s
AVG Dyn Air = 17.2 g/s

So I take a look at our tunes:

Buddy's car:
40 kPa @ 1200 RPM = 57.7 % (VE table Value)

LABELS Idle Airflow
°C In Gear
-40 22.000000
-20 19.000000
0 15.200195
20 12.200195
40 10.400391
60 8.599609
80 7.400391
100 7.099609
120 7.099609
140 7.099609

LABELS Idle Aiflow Parked
°C Value
-40 33.000000
-20 28.000000
0 23.000000
20 21.000000
40 19.000000
60 14.000000
80 10.000000
100 9.000000
120 9.000000
140 9.000000

My car:
70 kPa @ 1200 RPM = 51.5 % (VE table Value)

LABELS Idle Airflow
°C In Gear
-40 34.000000
-20 31.000000
0 27.200195
20 24.200195
40 22.400391
60 20.599609
80 19.400391
100 19.099609
120 19.099609
140 19.099609

LABELS Idle Aiflow Parked
°C Value
-40 45.000000
-20 40.000000
0 35.000000
20 33.000000
40 31.000000
60 26.000000
80 22.000000
100 21.000000
120 21.000000
140 21.000000

So at the moment, I have no idea where to start in my tune to get this idle a little more desirable.

[jfpilla]

Glad you found the source of the problem. What you found on your friends car is what lead to the tuning procedure suggested. Go to the thread, Idle (Transition) Tuning and do it step by step. Now that you've seen what the result is like you have a head start.

[TAQuickness]

I'm getting a bit confused as to how the car is deriving it's desired airflow rate.

The IAF table represents the desired airflow based on ECT.

The IAFP table represents the required air flow based on IAT.

How is the PCM calculating how much air it needs to idle?

[Dirk Diggler]

I'm getting a bit confused as to how the car is deriving it's desired airflow rate.

The IAF table represents the desired airflow based on ECT.

The IAFP table represents the required air flow based on IAT.

How is the PCM calculating how much air it needs to idle?


I may be wrong but i think this is figured out by the PCM based on the ve table, map sensor and IAT sensor. This may be the reason why jpfilla suggested the ve table needing to be correct

[jfpilla]

I'm getting a bit confused as to how the car is deriving it's desired airflow rate.

The IAF table represents the desired airflow based on ECT.

The IAFP table represents the required air flow based on IAT.

How is the PCM calculating how much air it needs to idle?

I don't think you're asking for engine theory. If so, someone might want to do it.
I'll answer what I think is confusing you.
When you log Dynair g/s or Maf g/s you are getting the actual airflow at various ECT's. You then need to program those values to the Idle airflow table by ECT. This will make this table correct.
You then need to match the logged Iacdes g/s to the logged Dynair or Maf g/s numbers, by IAT. You change your logged Iacdes values by use of the Idle Airflow Parked table. When the Iacdes values are correct they represent actual airflow. When all three table are logging about the same numbers, they are properly set. Surging is eliminated because the TB comes to rest at the right place and doesn' need to hunt. Since a mod like a cam makes the logged numbers jump some, it might not be perfect. That's when slight SOP adjustments may be needed.
Did you do what Nick suggested, for F-bodies, at the end of the Idle Tansition Thread?

[TAQuickness]

OK, if I had hair, I'd pull it out. What you are saying makes perfect sense, but after several attempts, my logged values are still the same. My logged dynamic air is very close to the values in my idle air flow table. From your previous post, this is the goal, then the Idle Airflow Parked table gets adjusted to make the desiac_b match the dynamic airflow. I got as far as scaling the entire IAFP table by 125% and it still makes no difference.

The only thing I can think of at this point is that the desired air flow is somehow affected by the MAF - and mine is not available to be connected at the moment.

[jfpilla]

It sounds like your IAC is maxed.
This is what Nick suggests, after that, I'm guessing, because I have not tuned an f-body. I will see if I can get someone to chime in.

"Process is the same for the F-body. You just have to make sure the IAC motor is within range to give the motor the air it wants. With a big cam car the IAC uses up alot of its range or all of it just to get enough air thru for idle on a cold start. Two ways to fix this. You can drill the hole in the blade out bigger or you can adjust the closed position set screw to open the blade more. Adjusting the screw will require a reset on the TPS to get it to read 0% at idle. The stock camaro that I have idles around 65 steps when hot. Use that as a target to determine how big of an adjustment to make. Once you have the IAC motor within range, then start trying to get the DESIAC gms/sec to match close to the MAF gms/sec."

[TAQuickness]

Here are the IAC steps through a cold start:

LABELS ECT °C IAC Steps (Average)
ECT 140
-40
-20
0
20
40 120.011468
60 42.475177
80 20.040307
100 18.943318
120
140


Those numbers actually look a little low to me after the car warms up

[jfpilla]

Here are the IAC steps through a cold start:

LABELS ECT °C IAC Steps (Average)
ECT 140
-40
-20
0
20
40 120.011468
60 42.475177
80 20.040307
100 18.943318
120
140


Those numbers actually look a little low to me after the car warms up

Your steps are in range enough not to create the problem.

Do an idle reset. Turn on key, pull fuse, wait 10 sec. turn off key, replace fuse.

Is your throttle blade drilled out(too much)?
Your VE's could be too high?
I have heard that in some unusual cases the logged IAC values don't respond, but the car runs fine?
After this I'm lost and would suggest LS1 Tech.

[TAQuickness]

I'm lost too! But on the other hand, I have different fingers :lol:

I'm picking up the pig tail connector tonight so I can run the new 85mm MAF.

I'm starting to think the PCM needs the MAF for the idle process.

Have you performed the idle transition tuning on a !MAF car?

[jfpilla]

I'm lost too! But on the other hand, I have different finger :lol:

I'm picking up the pig tail connector tonight so I can run the new 85mm MAF.

I'm starting to think the PCM needs the MAF for the idle process.

Have you performed the idle transition tuning on a !MAF car?

I've done it on C5's only. My f-body info is second hand at best. FWIW I'm not a fan of Mafless. I've done the Mafless and 0'd Maf, on my car. I just don't think it's likely that we can accurately tune and not have an MAF sensor to take up for varing conditions and minor tuning errors. Here's how my C5 has been tuned. The injector flow rate and PE rpm were calculated, first. Then the VE's were set with the MAF 0'd. Mafless might be better but my car's IAT sensor is part of the MAF and I think we should let the GM multi million $ system do it's job. I then got my trims in line by way of the MAF table. Then did the idle transition tuning. My ltrims and strims became flat and are now -2 to 0. It makes sense since anything that changes airflow should affect trims. What remains is checking the Idle Airflow Parked over 40C as the weather warms.

[TAQuickness]

The MAF is going back in 20 minutes :D

I'll post my results tomorrow afternoon