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Thread: About to throw in the towel nailing down idle

  1. #81
    Senior Tuner 5_Liter_Eater's Avatar
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    Glad to hear it!
    Bill Winters

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  2. #82
    Did you use the stock coast down spark table?

  3. #83
    Senior Tuner 5_Liter_Eater's Avatar
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    Yes.
    Bill Winters

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    Out of the LSx tuning game

  4. #84
    Tuner TYRFRYR's Avatar
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    Quote Originally Posted by 5_Liter_Eater
    I'd really like it if someone were to try this. I've attached the config I used. histos 10 and 11 will do the job. Most of the other histos will be of no good to anyone as they utilize my user defined PIDs for my AEM through my AC pressure sensor.
    I was following the write up that 12secSS posted. This approach is a little easier for me to follow. I was able to dial in that little extra to get my 236/240 at 112 to idle like a baby at 800.

  5. #85
    Senior Tuner 5_Liter_Eater's Avatar
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    ***Updated for clarity and added CFCO recommendation 7/18/12***

    I just did this again and refined the process a little. As of 3/23/11 this is now updated for 2.23 and the config/histo changed to plot dynamic airflow. I have only ever done it on a manual car so the auto steps are SWAG's.

    - Set you're target idle speed to whatever you would like it to be (be reasonable based on your cam)

    - Set your idle speed minimum to the same as your lowest target idle speed. IE: I have 900 when cold ramping down to 750 when warm so I'd use 750 for idle speed minimum.

    - Make your idle spark table match the corresponding columns from your HO spark table. The reason for this is that the idle spark table is only referenced when the speed is 0 and the HO table is referenced when moving. I can't see a reason for wanting them to be different. If you make changes to one, make them to the other as well. You do want the advance in the idle cells to not be optimum. I suggest ~15-20 degrees. This is so the adaptive idle spark can add spark and actually have it do something. If you have your idle spark at the ideal then adding to it won't help.

    - Under Idle, Idle Airflow, Base Running Airflow, zero out the entire Airflow Final Minimum table. This prevents the PCM from predicting any minimum airflow which would prevent us from finding the real minimums.

    - I suggest leaving the idle adaptive spark control overspeed and underspeed tables and adaptive idle proportional and integral tables as they come stock. Since I can't find an empirical way to determine how much to edit these tables, i leave them alone and they seem to do a nice job even when I had my lopey big overlap cam. The other thing I'll say about these is the airflow tables under proportional and integral should remain stock, even on a scaled tune. I've tried cutting them in half along with all the other airflow/airmass related tables when I do a 50% scaled tune and it doesn't work out well.

    - Unlike gen 3 idle tuning, start with a warmed up engine. AC on. This is where idle airflow will be the smallest. While parked, start the motor and in VCM controls command the different RPM's in the airflow final minimum table; 650, 800, 1000, 1200, etc. As of 2.23 you cannot type in numbers into this field anymore. It stops at 1200 now. Leave it at each cell for at least 30 seconds, 60 is better so the values in each cell can stabilize. You may have a hard time staying in the 650 RPM cell until later when the numbers get more accurate or if you have a big cam you may not be able to get it to go that low at all. Automatic guys will want to do this in park and again in drive with the e-brake on and tire stops for safety. Use the park numbers for park and neutral and the drive numbers for all other gears, although in actuality you will probably only be able to get the 660 and 800 numbers while in drive. Manual guys use the neutral numbers for all gears.

    *Note that the histgrams are set up in g/sec, because thats what I like. The units in your tune for the final airflow min table may default to lb/min. Make sure they match before proceeding. Either change the histo to #/min or change the units in the tune to g/sec.*

    - Using histogram 10 on average (A), which plots dynamic airflow against the final idle airflow minimum table. The idea earlier was to command the lowest RPM in each field so we find the minimum flow for each cell. Simply using the "-" function (lowest value) of the histogram doesn't yield good results. Copy the numbers you got in histo 10.

    - Paste the numbers you get directly into the Airflow Final Minimum table for all gears (auto guys use the numbers for park and neutral and re-do in gear and paste those values in all other gears). Leave the values above the RPM's you stopped at as zeros and make up some numbers for the 450 and 250 RPM cells that follow the trend of the line. Then sutract 20% from the whole table (select all and multiply by .8). Don't ask, just do it.

    - Flash and restart the engine. Use histo 11 to plot the idle adapt advance spark against the final idle airflow minimum table using the average (A). Command the RPM's again, just like before. Copy and paste these numbers (paste special, multiply by %) into the appropriate cells in the tune. (again, auto guys will need to do this in park and drive) Raise or lower the lower RPM cells that are toolow to idle in accordingly to make a straight line. Lather, rinse, repeat until the adaptive spark numbers are +-1 degree. I realize we're taking the number of degrees that the adaptive idle control is having to add or remove and pasting that into the tune as a percentage of airflow and that doesnt make any sense, but it works. With each iteration you will see the adaptive idle spark getting closer to zero. The less the adaptive idle spark has to work the closer we are to the real idle airflow minimum. Even though the adaptive idle spark does not come into play when moving, since the airflow numbers are correct there should be no dipping, hanging or flaring when returning to idle.

    Lastly for the manual guys, I recommend disabling CFCO. I was still having some flaring/dipping when I was in traffic at low RPMs and pushed the clutch in. Disabling CFCO cleared this right up.
    Last edited by 5_Liter_Eater; 07-16-2015 at 03:09 PM.
    Bill Winters

    Former owner/builder/tuner of the FarmVette
    Out of the LSx tuning game

  6. #86
    Senior Tuner 5_Liter_Eater's Avatar
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    Learned some things tonight. I was wrong about my low idle timing coming from adaptive spark pulling it. Took a look at my idle spark table and it was really low. Once I made it match my HO spark table (idling ~28*) it raised the RPM dramatically. I used histo 11 a few times and was able to get the 800+ cells dialed in but it would not idle down to 650 where I was commanding, when I was running 13* at idle it would. So the adaptive idle proportional and integral and the idle adaptive spark control seem to have their limits. Ran out of time to finish testing but if you are having trouble with the idle not going as low as you'd like even with a zero'ed RAF then take some out of your idle spark table.
    Bill Winters

    Former owner/builder/tuner of the FarmVette
    Out of the LSx tuning game

  7. #87
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    Thats really interesting 5L. I'll play around with that when I get a chance.

  8. #88
    Just so I understand this correctly:


    We determine the TRUE air flow min by ZERO out the table then taking whatever number comes up in histogram 10 and paste it in as now a Airflow Min number -%10?

    During the process we keep the idle control to ON (which really means adaptive idle ISN'T working)? So we use the error reports of adaptive idle to dial the air flow in to the earlier HO/base spark (they now match).

    How do you know you have the right spark table to being with?

  9. #89
    Senior Tuner 5_Liter_Eater's Avatar
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    Correct. Zero the RAF and use VCM controls to set the adaptive idle to "ON", which really turns it off for the first part so there is nothing affecting the idle. Then plug in the numbers you get into the RAF.

    A change I'm suggesting is to not go past 1200. Keep everything past 1000 or 1200 as 0's.

    Then for the second part you're seeing how much adaptive timing is being added or subtracted and using it as a reference for how far off the numbers are.

    I wouldn't worry so much how much spark is in the table at idle.
    Bill Winters

    Former owner/builder/tuner of the FarmVette
    Out of the LSx tuning game

  10. #90
    Tried it this weekend and failed. For some reason it got worse. I got my adpative idle down to within +/-1.5

    This car is possesed so I've put it up for sale:

    http://washingtondc.craigslist.org/n...301246299.html

    I'm going to take the car to a tuner in the area and have them do it. I hate to give up so fast, but I need this car to run well enough to daily drive. As it is right now - I just can't "deal" with its idle problems. If after I have it tuned its 100% then I may rethink it.

    Not sure what I'm going wrong, but it sure as hell isn't running right.

  11. #91
    The numbers I got on the RAF were 3.6 across the board. That doesn't seem right at all.

  12. #92
    Senior Tuner DSteck's Avatar
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    Vald, you have a QM600 car right? Want me to send you my tune file?

    DSX Tuning - Authorized HP Tuners Dealer
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  13. #93
    By QM600 you mean cam - nope. I'll list the specs as this should help. Maybe your tune would have some good starting points for me. I'd appreciate you emailing it to me:

    juan.barnett@gmail.com


    CNC'ed L92 heads, flowing 360cfm intake and 280 cfm exhaust.
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    motor was built and speed density tuned by Charlie Williams @RPM motors

    Really wished I could get in touch with Charlie - but he is impossible to reach out to. Who knows, the previous owner might have changed something from what Charlie had originally set up.

  14. #94
    Senior Tuner 5_Liter_Eater's Avatar
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    Why don't you go back to those numbers that worked well before and decrease the #'s in in the areas its hanging at to give you the cruise control?
    Bill Winters

    Former owner/builder/tuner of the FarmVette
    Out of the LSx tuning game

  15. #95
    Quote Originally Posted by 5_Liter_Eater View Post
    Why don't you go back to those numbers that worked well before and decrease the #'s in in the areas its hanging at to give you the cruise control?
    thats the plan for now. you got me that far

  16. #96
    Got a response back from the actual builder of the engine:

    I looked the file over, located the vin, and know it came from an engine build I did several years ago. The file does not match any changes/updates I have on record for the vin and in fact, the system has been switched to a speed density calibration from a MAF based calibration.

    My advice is to have a good local tuner start from scratch and straighten it out. I might need only a minor value change but let the tuner decide what his best course is

    Let me know if I can help.

  17. #97
    Tuner in Training
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    5LE: What cam did you have in the GTO you were tuning?

    I'm trying to figure out the idle for my 05 GTO with a 238/242 112LSA cam. I can get it to idle stably but it's not "smooth". It's not exactly a paint shaker, but it doesn't have a consistent lope or rhythm. I wonder if the AFR is off? Should my WB read stoich at 1000 rpm idle? Scanner shows stoich, and about 62kpa on the MAP.

    I haven't found any idle timing that works better than the stock table so for now it is stock.

  18. #98
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    Also: Zero'ing the final idle airflow table is something that might lead you to expect the engine wouldn't run. My guess is that because the proportional/integrative tables work by adding or subtracting airflow, the engine still gets enough airflow to run.

    In my case desired idle rpm is 950. If I zero the final idle airflow (why do people call it RAF?) table the engine will run and I can command rpms down to around 750 before the VCM falls into "safe" mode for reasons I still don't understand.

    Also .. if you have no MAF, can you log "dynamic airflow" and use that instead?

  19. #99
    Senior Tuner 5_Liter_Eater's Avatar
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    I have never owned a Goat. I've tuned my friend's but it is bone stock with a CAI. Before I had my blower I had a 238/242 .605/.610 112 cam which is what prompted me to create a procedure for gen 4 idle airflow tuing.

    It know its not intuatuve that it still runs with the final airflwo min zero'ed out but it does...

    It's referred to commonly as RAF because on the gen 3's the table was called base Running Air Flow.

    If you don't have a MAF or you are in SD you should be logging and using VE airflow instead of Mass Air Flow.
    Bill Winters

    Former owner/builder/tuner of the FarmVette
    Out of the LSx tuning game

  20. #100
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    How do I know where to start on the idle timing map? My cam is 238/242, 112 LSA, 10 degrees overlap.

    Right now my idle airflow table is set to 9.5 everywhere 1200rpm and below, idle spark is stock, and all other idle tables are stock. Desired idle is 950, actual is usually around 1025.

    If I add more advance, it speeds up. If I start cutting down the airflow it runs worse. Oftentimes it gets really touchy and wants to drop into safe mode, especially if the rpm gets too low when I'm engaging the clutch.

    In other words the idle at present is a lot more acceptable than anything else I've come up with. I also don't really know what my expectations should be. I'd love for it to idle with a consistent lope, right now it's just a bunch of random stumbling and vibration.