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Thread: Explain throttle cracker and follower..again!

  1. #1

    Default Explain throttle cracker and follower..again!

    The hardest part of tuning is just understanding what each table is doing. I find that some of the descriptions in EFI Live don't really answer what the table is doing but rather what that table ties into. The throttle cracker and follower are two that I keep getting mixed up and I'm not afraid to admit it!

    Growing up with tuning carb's I can see some of the similarities. If I am not mistaken, the TC is what controls the return to idle once the throttle is lifted. If you have a car that the rpms hang after pushing in the clutch I assume you reduce the grams/sec of air that the IAC allows into the motor. One question I have is how much of a change is significant?

    I see that this is also based upon MPH. I again assume that those MPH limits control the window in which the TC is active and adding air to the motor.

    Are these values added to the desired air flow table? Is this the base table? This now leads to the proper way to dial in the desired air. I have done maps to log grams/sec vs. coolant from a cold start. Once these values are logged I assume this is the actual grams/sec that the motor is ingesting at that rpm and coolant temp. Should these value match the B4307 table? What if the throttle blade has been cracked?? Doesn't this skew the numbers? I am on a big rant with this but know that all these tables interact. I just need a better explaination of the overall big picture.

    Oh yeah.............how does the throttle follower work?

    I am having some issues with a 02 A4 F-body with a H/C setup that is pushing me to throughly comprehend this.

    One last thing is what table controls air on cranking/startup? Airflow Parked?

    All this after a couple glass's of Grey Goose!

    Howard
    Last edited by Redline Motorsports; October 6th, 2006 at 04:25 PM.

    www.redline-motorsports.net

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    2006 ZO6 895/866 with APS TT
    2010 SSRS Camaro HTR-900TT (798/801)
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  2. #2
    Lifetime Member TAQuickness's Avatar
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    Start up airflow: B4303, B4343.

    Airflow parked I believe to be a reference value for the PCM. I have not found a way to tune this table that I'm comfortable with.

    TC engages after the car is rolling and disengauges just before the car comes to a stop - mostly effects your rolling idle and transitions from rolling idle to stationary idle.

    TF is always working and I've found it to have more of an effect on stationary idle.


  3. #3

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    What is the difference between "adding" air by raising the IAC effective area vs. desired airflow? If I understand it correctly, the IAC des air is internal PCM conversion to change the grams/sec values into steps. Seems to me we should leave IAC effective area alone and only change the desired. I am also trying to confirm that the desired is the root base air flow that is leaked into the TB and that many other tables contribute to that value. If the the throttle blade is not touched from the factory, then the ONLY place more air can come from is through the IAC. Now the trick is to add, or delete air for the variety of conditions the engine sees. Another question I have is; once the IAC moves off the seat,at some point it has to be at its limit. I know as a rule of thumb that 60-90 IAC counts at idle gives the IAC enough range to have the ability to shut air off and add more air quickly. I noticed on this A4 car that it idles at 56 in P/N but as soon as it goes in gear it jumps to 160's. This is clearly too much air as the car wants to pull. I played with the bidi controls and the car feels real good in gear at 100-115 counts. What is the proper way to calculate the air requirements to reduce the counts in gear by 50 counts? Desired airflow in gear? I am also trying to smooth the transition from in gear to out of gear.

    Finally, I got the car idling decent and starts up great cold. Warm startup is rough for the first 10 seconds and then stabilizes. Could this be from the start up friction airflow? Seems to be the car needs more air on warm start.

    Thanks

    Howard

    www.redline-motorsports.net

    1-954-703-5560

    2006 ZO6 895/866 with APS TT
    2010 SSRS Camaro HTR-900TT (798/801)
    2011 HTR-850R Camaro
    2012 ZL1 Auto (10.33@135 MPH) Video Here!

  4. #4
    Lifetime Member TAQuickness's Avatar
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    IACEA is another reference value used to conver airflow to steps. At one point I liked this method to dial in the idle, but have since found it better to leave this table alone (for cable driven TB's anyway, can't speak for ETC).

    Desired airflow, B4307, is the base air flow and all other tables will add or subtract from this value. RAFIG and RAFPN will give you the data you need to adjust B4307.

    will get back to you with more info later.


  5. #5

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    Is there a way to accurately monitor all the tables that add/subtract. It would be cool to see the PCM going threw its motions to see when air is being added to the DAF. Can FS derive a total?

    Thanks

    Howard

    www.redline-motorsports.net

    1-954-703-5560

    2006 ZO6 895/866 with APS TT
    2010 SSRS Camaro HTR-900TT (798/801)
    2011 HTR-850R Camaro
    2012 ZL1 Auto (10.33@135 MPH) Video Here!

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    Quote Originally Posted by Redline Motorsports
    Is there a way to accurately monitor all the tables that add/subtract. It would be cool to see the PCM going threw its motions to see when air is being added to the DAF. Can FS derive a total?

    Thanks

    Howard
    Log the IAC - xxx (airflow) DMAs - especially the short and long term corrections. You can watch the PCM go through it's routines from startup via the Data (F9) Tab.
    You will need to separate them into groups due to the their "Channel" consumption. I separated them into Startup, Sitting and Running. That way you can select the unique PIDS for each group along with RPM, MAP, IAT, ECT , VSS etc.
    FWIW.

    joel

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    Quote Originally Posted by Redline Motorsports
    . Warm startup is rough for the first 10 seconds and then stabilizes. Could this be from the start up friction airflow? Seems to be the car needs more air on warm start.

    Thanks

    Howard
    Mine needed LESS fuel at warm startup (cold startup was very good). I scaled the cranking VE to match the Percentage reduction of my EFILive Main VE versus my Stock Main VE table in the Idle RPM range. Big help.

    FWIW.

    joel

  8. #8

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    Joel,

    Good pointers! I only assumed that it wanted more air as when I crack the TB a bit a try to start it, it starts decent.

    When you say to separate them are you logging these "groups" one at a time?

    www.redline-motorsports.net

    1-954-703-5560

    2006 ZO6 895/866 with APS TT
    2010 SSRS Camaro HTR-900TT (798/801)
    2011 HTR-850R Camaro
    2012 ZL1 Auto (10.33@135 MPH) Video Here!

  9. #9

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    Noticed a pid named IAC Final Airflow Sum................hmmmmm. Actually I found all kinds of neat pids!

    I just went and reviewed a log from this car.

    Based on a coolant temp of 90 degrees F;

    DAF 1.456
    Startup Friction Airflow Correction 2.500
    Engine Speed Compensation 6.666 with a .50 multiplier so its 3.333

    All other air adder tables where 0.

    Based upon a coolant temp of 131 degrees F;

    DAF 1.029
    Startup Friction Airflow Correction 2.500
    Engine Speed Compensation 6.666 with a .50 multiplier so its 3.333


    Since the TC and TF are speed based air adders, I don't see how they effect startup and idle in and out of gear.

    I can see once you break the mph values that those parameters will add additional air. How much air is a significant amount?
    Howard
    Last edited by Redline Motorsports; October 9th, 2006 at 03:05 PM.

    www.redline-motorsports.net

    1-954-703-5560

    2006 ZO6 895/866 with APS TT
    2010 SSRS Camaro HTR-900TT (798/801)
    2011 HTR-850R Camaro
    2012 ZL1 Auto (10.33@135 MPH) Video Here!

  10. #10
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    Yes, I logged them separately so I could correlate with the other non-IAC parameters.

    I think TF is applied to all throttle Deltas (non idle).

    0.2 g/sec TC deficiency will cause my car to surge at 2000 RPM - and slightly below 2000. It's "significant"
    to a passenger -> "WTF was that?!!".

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