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Thread: Gen4 idle tuning guide

  1. #241
    When people here talk about Base Airflow, do they mean the Airflow Final Minimum table? Base Airflow sounds like starter values the PCM works with to determine desired idle airflow, while Airflow Final Minimum just sounds like minimum values. Unfortunately I can't find the former table anywhere. Increasing minimum idle airflow could of course have the desired effect, but wouldn't adjust for things like weather or the air conditioning compressor kicking on.

    Thanks. I've got a heads/cam LS7 with a NW 102 and the crankcase vented to a catch can. The TB scalar is set properly but it doesn't want to idle with much MAP (i.e. it just stalls). Presumably this is because of the lack of a PCV system, and me not knowing how to increase base airflow (yes the ECT scalar is set to 7,190).
    Last edited by Grant; 11-22-2019 at 02:59 AM.

  2. #242
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    Base running airflow, idle airflow, final minimum airflow, RAF, BRAF, etc that people refer to are all different names for each other. the table name has changes in different generations of controllers but same concept.

    Is there an open vacuum line to the engine now with the catch can install? I see this mistake made often.
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  3. #243
    Quote Originally Posted by charcoal03silvy View Post
    Base running airflow, idle airflow, final minimum airflow, RAF, BRAF, etc that people refer to are all different names for each other. the table name has changes in different generations of controllers but same concept.

    Is there an open vacuum line to the engine now with the catch can install? I see this mistake made often.
    Thanks, that's very helpful. I wish the software described these tables better (or better yet published formulas); Final Airflow Minimum sounds like a floor, not the starting point, for desired airflow calculations.

    No there's no open vacuum lines anywhere. On LS7s, the intake manifold pulls air from the valley cover, which draws in air from the valve covers, which draw from the post-MAF intake. So I lost a source of intake air at idle.

    I increased the Final Airflow Minimum tables a lot and got the car to idle. It still stalls a lot due to the very light Tilton clutch/flywheel setup, but I think I've got a decent base to work from now. I'll go through the OP procedure now.
    Last edited by Grant; 11-28-2019 at 11:20 AM.

  4. #244
    I've gone through the OP procedure, and am not having any luck.

    Tune and logs are attached, but the pic summarizes what I'm seeing. Despite throttle position being fixed at 10.98% and timing at 22.00 degrees, it's very difficult to start it on a "stable" idle. Even then it oscillates from 950 to 1650 RPM over a period of about 2 seconds. Eventually it stalls. Decreasing Final Airflow Minimum, even by as little as 0.5 g/s, makes it stall much sooner. Increasing it makes it oscillate at a higher RPM. What I'm really having difficulty understanding is why the idle is sometimes more or less stable when throttle position and timing aren't changing.

    The car is an LS7 with Mast 305 heads, a Katech Torquer 110 cam, NW 102 TB, and Deatschwerks 65 lb injectors on E85. The tricky part is the Tilton carbon clutch, which is 17 lbs complete with flywheel. There's also no PCV system, which probably increases the necessary throttle angle.

    In this log I'm seeing significant negative fuel trims on bank 1, but that's not usually the case. The only other thing I can think to try is to lock it into open loop fueling, but I really doubt a few percent here or there will make much difference.

    Any suggestions? Thanks for any help.
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    Last edited by Grant; 12-19-2019 at 12:42 AM.

  5. #245
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    Have you tried running MAF only to see if it still behaves that way? From the picture, the MAF looks relatively consistent through the surge/stall scenario while the VE is jig sawing. It may be worth a try with MAF only by setting dynamic air low: disable=100, re-enable=50. If it smooths out, it would suggest the VE tables need work.

    Just another thought, I've had idle issues with the LS7 card MAF on turbo setups that have lots of bends in the charge pipe. I've had great results installing air straighteners inside the charge tube just before the card maf to reduce the turbulence it sees and that has greatly helped tune out the idle surges. (your mileage with this technique may vary)
    07 Silverado 4.8 Turbo 595hp/626ft-lb ET: 11.68@116
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  6. #246
    Thanks, that might have helped a bit. I can get it idling at a lower RPM with MAF only, but it still eventually oscillates and stalls. Fuel trims are similar.
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  7. #247
    Advanced Tuner jsllc's Avatar
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    you are missing these. There a some that help with predictive and TB changes

    12940 - Requested Airflow Low Barometric
    12941 - Requested Airflow Medium Barometric
    12942 - Requested Airflow High Barometric

    Also [ECM] 2154 should be 6553 for your ECM and NW102. [ECM] 12087 is not right needs to trend not step. Your chances of getting idles with zero on adaptives are well zero. Your mods are too radical especially with no flywheel weight. My clutch assembly is 25 lbs and it is very difficult to get going without lurch and jerk in 1st and even some in 2nd.


    https://forum.hptuners.com/showthrea...l=1#post531912
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  8. #248
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    Quote Originally Posted by jsllc View Post
    you are missing these. There a some that help with predictive and TB changes

    12940 - Requested Airflow Low Barometric
    12941 - Requested Airflow Medium Barometric
    12942 - Requested Airflow High Barometric

    Also [ECM] 2154 should be 6553 for your ECM and NW102. [ECM] 12087 is not right needs to trend not step. Your chances of getting idles with zero on adaptives are well zero. Your mods are too radical especially with no flywheel weight. My clutch assembly is 25 lbs and it is very difficult to get going without lurch and jerk in 1st and even some in 2nd.


    https://forum.hptuners.com/showthrea...l=1#post531912
    I had to spend two hours reading through this whole thread and hours trying to tune my idle today to come to this conclusion. My setup is way to radical to turn all adaptives off and expect an idle. I've bit off a little more than I can chew. I have been researching for years, but just now getting my feet wet in tuning. I tried to add a bunch of extreme modifications and start from scratch due to a botched tune. I wanted to have an SD only tune. Easier said than done. After forcing closed loop in the scanner I noticed a lot of improvement. I think I'll concentrate on a MAF only tune and fix my VE table later. I did learn that I needed to modify my [ECM] 2154 and [ECM] 2174 to account for my 102mm tb, so that should help a little with tuning tomorrow. I also need to look into modifying my EIOT due to my cam I think.

    Oh, my car was idling between 1500-1700rpm and I couldn't figure it out. Adjusting "Airflow Final Minimum" and timing wouldn't bring my rpm down. It would make it harder to start or to keep running though.

    '09 G8 GT
    SBE, MAD ported LSA 2.38/10, 210lb inj, 102tb, 238/242 112, ls7 maf, SD 2-bar.

  9. #249
    That doesn't necessarily seem like the best cam for an LSA blower based on the specs in your signature, but you should be able to get it to idle with the adaptives off. It sounds like you fixed your TB scalar, but I'd also go hit the basics again just to make sure you didn't miss anything: make sure your injector data is correct and get the air/fuel dialed in pretty closely at idle before you start fine-tuning it, etc.

    This idle tuning procedure is actually the last thing to do in my book. It will put the final polish on idle quality and get the airflow and spark corrections to stop fighting each other, but I wouldn't bother with it until the rest of the tune is good.

  10. #250
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    Hello All, there is so much good information in this thread! But being that Im so green at this, the more I read the more confused I get. I have been taken shots at trying to get my idle dialed in after upgrading my camshaft and lifters. It starts and idles on its own, but it has a shake or shutter when it sits at idle. I was wondering if anyone can take a look at my latest adjustments and see if you could tell me if for one, I am heading in the right direction, and if you have any suggestions how to get this shutter to smooth out?
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  11. #251
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    Tagged for future reference.
    Tuned a 6.2 with a cam last night. Then found this just now. Wish I'd read this before starting.

  12. #252
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    Does this method work with a SD tune also

  13. #253
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    Quote Originally Posted by Race gto View Post
    Does this method work with a SD tune also
    when maf is failed the effective area max fail comes into play so set it to like 200 but aside from that is all the same method

  14. #254
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    Awesome info in this thread!!

    I picked up a '13 CTSV that made its way from Denver to Houston and has the Lingenfelter 700+ package and the dealership couldn't find record of the actual cam spec's. It does have a noticeable lope. My MPVI2 arrived on Monday so I'm picking up where the other tuner left off.

    The idle is relatively stable but hunts a little after rev up or coming to a stop.This is my first attempt to retune it, as it's very rich and the fumes are not just from exhaust (longtubes with cats) but also there's noticeable stumbles on quick acceleration, and very lazy startup after warmup. I've followed the procedure Mike put together and I have the idle stable now, whereas it was dying and wouldn't idle without partial throttle, but I'm having a massive amount of frustration of getting it to stabilize the idle after reving up or coming to stop on coast down. Even when I pull in my garage, it will stall with partial throttle.

    Should I continue to work on the Airflow Minimum table or work on the Spark base table? Attached is idle and drive log, along with the current tune.
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    Last edited by all_b00sted; 3 Days Ago at 11:09 PM.

  15. #255
    Tuning Addict 5FDP's Avatar
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    Fix the fueling before you worry too much about tons of idle changes. If the fueling is all wrong, so will your idle airflow adjustments.

    That tune needs some help for sure. Look at how stupid rich they setup power enrichment. It floods the engine with fuel and I have no doubt that is part of your bogging problem.

    14.68/1.500 = 9.78 AFR. This massive dump of fuel can cause some of your knock retard as well. No idea what the hell this previous tuner was thinking. For now just change the whole table to 1.300 (11.2 AFR), that is nice and safe while you fix other issues.


    Invest in a wideband 02 sensor, this is a must for tuning. You'll want to go over the MAF curve and VVE to get fueling squared away. Things tend to go smoother or fix underlying issues when it's not overly lean or rich.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  16. #256
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    Quote Originally Posted by 5FDP View Post
    Fix the fueling before you worry too much about tons of idle changes. If the fueling is all wrong, so will your idle airflow adjustments.

    That tune needs some help for sure. Look at how stupid rich they setup power enrichment. It floods the engine with fuel and I have no doubt that is part of your bogging problem.

    14.68/1.500 = 9.78 AFR. This massive dump of fuel can cause some of your knock retard as well. No idea what the hell this previous tuner was thinking. For now just change the whole table to 1.300 (11.2 AFR), that is nice and safe while you fix other issues.


    Invest in a wideband 02 sensor, this is a must for tuning. You'll want to go over the MAF curve and VVE to get fueling squared away. Things tend to go smoother or fix underlying issues when it's not overly lean or rich.
    Absolutely investing in a wideband. I just ordered, tonight in fact, the AEM x-series controller w/ gauge; will take full advantage of the Pro input. What is the path to the table you're referring to for making the change?
    Fuel.png

    I can only imagine the previous tuner, who is in Colorado was doing something for the change in DA up there, but I've also found that certain things were let the same as the stock tune when I compared them, such as final air, startup air and ETC area scalar.

    It does have ID 850's and a Nick Williams 102mm TB, but it seems they just made adjustments on the Injector Controls and Flex Fuel. It does have a AEM flex fuel sensor but I'm also going to replace that with the GM model since it will report PID to the instrument panel.

    Thank you for the input.
    Last edited by all_b00sted; 3 Days Ago at 12:28 AM.

  17. #257
    Tuning Addict 5FDP's Avatar
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    Engine > fuel > power enrichment and then EQ ratio. That is the commanded fueling value for power enrichment.

    Being Colorado doesn't really matter, the car has enough sensors for MAP/Baro, IAT, ECT etc etc to help figure out what to do. They don't make different calibrations for stock vehicles for the people that live in Arizona, the Canadian Yukon or pikes peak type of thing. I just don't think they understood what PE does and how to use it. Power enrichment EQ ratio is a set and forget table. You are making a request and the goal is to match that request by getting the data correct in the MAF/VVE. If you ask for 11.2 AFR but see 10.5 or 12.0, that just means there is large error between what is commanded and what is coming out the tail pipe. Adding or removing "fuel" from the airflow model is how things get fixed.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  18. #258
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    Quote Originally Posted by 5FDP View Post
    Engine > fuel > power enrichment and then EQ ratio. That is the commanded fueling value for power enrichment.

    Being Colorado doesn't really matter, the car has enough sensors for MAP/Baro, IAT, ECT etc etc to help figure out what to do. They don't make different calibrations for stock vehicles for the people that live in Arizona, the Canadian Yukon or pikes peak type of thing. I just don't think they understood what PE does and how to use it. Power enrichment EQ ratio is a set and forget table. You are making a request and the goal is to match that request by getting the data correct in the MAF/VVE. If you ask for 11.2 AFR but see 10.5 or 12.0, that just means there is large error between what is commanded and what is coming out the tail pipe. Adding or removing "fuel" from the airflow model is how things get fixed.
    Totally understand what you're saying, appreciate the insight.

    I'm going to set the EQ to the value you recommended and see how it reacts.