Can you define these idle parameters?

[Redline Motorsports]

As nice as the parameter descriptions are, there are some they just don't describe enough for novices. The following are a few that I am just not exactly understand what they are controlling.

{B4307} Desired Airflow

This parameter is based upon ECT. As the engine warms up this table appears to let more air during idle into the engine and decrease it as it warms up. On a C5 this is based upon the throttle blade angle being dercreased....right? Also once this parameter is fully warmed up what controls that final throttle blade opening?

{B4308} Airflow Parked

When the IAC motor is in the park position this is the required airflow.
The IAC will be moved to the park position in situations like engine shutdown and key on. What determines the "park position? No IAC on a C5......why is it still referenced as such in the software? I guess the throttle blade has a tough job to control idle and not let the motor get too much air and raise the rpms.

{B4309} Throttle cracker air flow in gear

What is the throttle cracker function? When does it kick in and when should be adjusted?

{B4313} Throttle cracker decay rate

Does this control the rate in which at throttle returns back to idle after the throttle is released? For example; if you had a car that when you pushed the clutch in,after cruising, the idle would hang for a bit before returning to idle. Does this work for this?

{B4315} Throttle follower airflow as well as the decay for the same.

:nixweiss:

Any insight would be appreciated!

Thanks

Howard

[TAQuickness]

The 4307 is the required airflow to maintain idle. for non ETC's this table will adjust the IAC valve, for ETC, it will adjust the TB blade position.

not sure how to relate 4308 to an ETC car, but I believe this table represents how much air can flow thru the IAC in the park position at different IAT's. IMO, there is no reason for this table to change.

Cracker and Follower are used to help idle transitions, low speed drivability. The descriptions for these tables appear to be fairly accurate and you can see them in action by logging the respective PIDs.

[Redline Motorsports]

Is the throttle cracker only MPH controlled? By setting the values in 4311 and 4312 is this the only parameters to activate and deactivate this mode? I would assume that the rest of the related TC parameters only appliy during the activation window set between 4311 and 4312. Correct?

When does the throttle follower apply?

Seems like the ETC cars are a bit more confusing because many parameters refer to the IAC which doesn't exist.

What does the stall saver one do?

Thanks

Howard

[Blacky]

Is the throttle cracker only MPH controlled? By RPM and MPH. You need to be careful when adjusting the {B4309} table. If you increase the desired airflow too much it will increase the idle speed (and thus the RPM) pushing the PCM into the next rpm row of the table which may increase the airflow again (and thus the RPM) and push the PCM into the next rpm row and so on.
This table appers to have more influence on hanging idle speeds than the small amount of airflow that it commands, seems to suggest.


By setting the values in 4311 and 4312 is this the only parameters to activate and deactivate this mode? I would assume that the rest of the related TC parameters only appliy during the activation window set between 4311 and 4312. Correct?
Correct.
I recommend leaving these set very low <5mph because the throttle follower is not active it the throttle cracker is not active.
So if you disable the throttle cracker by setting {B4311} and {B4312} too high then the throttle follower will not be active either.


When does the throttle follower apply?
See above. Throttle follower is to help with smoothing out the jerk that would otherwise occur when you lift off or get on the throttle quickly. It also prevents the rpms dropping too quickly in between manual gear changes.


Seems like the ETC cars are a bit more confusing because many parameters refer to the IAC which doesn't exist.
Most IAC parameters and calibrations do not refer to the IAC valve. They just happen to have the same name. IAC parameters and calibrations refer to the Idle Air Control that the PCM performs. The Idle Air Control can be accomplished either using the IAC valve (non ETC) or using the throttle (ETC). Most idle air control settings are specified in grams/second which can be applied through the throttle or IAC valve.


What does the stall saver one do?
The stall saver mode is supposed to kick into action to prevent the engine stalling when the RPM drops below a certain threshold. We have yet to successfully demonstrate that it has any effect at all.

Regards
Paul

[Black02SS]

I have seen Follower active at idle with the car not moving Paul. The only thing I can see on the follower to activate/deactive is it is based on TPA%. Correct me if I am wrong.

If the Cracker enable/disable is partly activating the follower, then you need to change the description of the Cracker settings to include that it enables/disables the follower, but I don't see the MPH being part of it. Not on a C5 anyway. I have sat at a dead idle with the car not moving and see follower being applied.

[Blacky]

Correct.
I recommend leaving these set very low <5mph because the throttle follower is not active it the throttle cracker is not active.
So if you disable the throttle cracker by setting {B4311} and {B4312} too high then the throttle follower will not be active either.


I have seen Follower active at idle with the car not moving Paul.
Chad, I stand corrected on that. I confused adding the cracker and follower airflows to mean one requires the other. It appears that they are both added, independantly of the other's value. Obviously if one evaluates to zero then it will have no effect in the sum.

Regards
Paul

[Blacky]

When does the throttle follower apply?
I'll try this one again (after a little research).

Throttle follower applies when the throttle is opening at a rate of more than {B4321} each 12.5ms.
The throttle follower is decayed when the throttle is closing or closed after a delay and at a rate determined by {B4317}..{B4320}.

Regards
Paul

[TAQuickness]

I'll try this one again (after a little research).

Throttle follower applies when the throttle is opening at a rate of more than {B4321} each 12.5ms.
The throttle follower is decayed when the throttle is closing or closed after a delay and at a rate determined by {B4317}..{B4320}.

Regards
Paul


+ $0.02. The follower activates via rate of change, or when TPS is greater than {b4321}. The follower was key to my being able to transition back to an idle state.

[jfpilla]

I would not describe B4307 as controlling idle. It's confusing. That's what B4603 does. B4307 Desired Airflow (aka Running Airflow) controls RPMs when the car is moving. This enables us to have idle RPMs when standing at various ECTs and to increase airflow, with B4307, in order to cruise some as the car moves at colder temps. The ideal would be to have, at full operating temps, idle RPMs meet DAF RPMs when coming to a stop.

[joecar]

Can this thread be made sticky, please.

[Redline Motorsports]

Yeah sticky it!

Needless to say my topics, which seem basic, seem to bring out the best in everyones view. I always seem to second guess what I want to post about but who cares.................this is what the forum is about.

Personally I appreciate the opinions and information that comes from these threads!

Thanks

Howard

[SSbaby]

Yeah sticky it!

Needless to say my topics, which seem basic, seem to bring out the best in everyones view. I always seem to second guess what I want to post about but who cares.................this is what the forum is about.

Personally I appreciate the opinions and information that comes from these threads!

Thanks

Howard
That's a healthy attitude! :exactly:

Your 'basic' questions help to give people a better perspective! :beer:

[joecar]

Yes, I learn alot from your questions, Howard.
:cheers:

[jfpilla]

Yeah sticky it!

Needless to say my topics, which seem basic, seem to bring out the best in everyones view. I always seem to second guess what I want to post about but who cares.................this is what the forum is about.

Personally I appreciate the opinions and information that comes from these threads!

Thanks

Howard

Howard,
Your questions are timeless. The answers today are not the same as they were 3 years ago and some will change again.
Joe:beer: