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Thread: Cold Start almost stall

  1. #21
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    Here is the latest log and AFR Video for you.

  2. #22
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    I can see you put your open loop fuelling back in. You need to work on that as you have a large dip around 42 seconds into the log. Also you ask for less fuel during the first few seconds after cranking then richen it up. It needs to be a lot smoother is all. I've put my settings back in and changed them a bit. See what you think on the log...

    I've added a little more to the VVE. It is very close to been in line with the MAF now. I have changed the open loop tables get you more fuel at initial start. I have added a little more to your startup air as well.

    I reckon this one will be the ticket (I probably shouldn't have said that lol)

    Graczyk Caprice Tune 28 DEC 20 (1) (4).hpt

    Edit:
    Now that your rpm dip is fixed, and we are working just on the cold start up now, feel free to shorten the logs down to about 30s after it goes into closed loop.
    Last edited by hjtrbo; 01-25-2021 at 12:21 PM.

  3. #23
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    I haven't touched any settings with open fueling during this back and forth with you. can you provide a screenshot where you are talking about?

  4. #24
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    Darn it. Egg on my face. I'm the one that needs to throw away my own tune. Please forgive me...

    Your climate is much colder than mine so you are entering areas of open loop tables that I will never get to hit. Sorry about this, my bad. Easy fix...

    Can you please add intake valve temp to your channel list. I'll need this to fix up the EQ commanded dip and at start.

    Regardless, please continue with my attached tune and get the next log when you get a chance.

  5. #25
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    its all good. I dont have IVT channel with the E38 on this car. I have intake air temp in the log. I wish i had the valve temp to help you out. The car is still "warm" so i will get you a log later tonight or in the morning (my time, EST).

  6. #26
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    Gee, your missing a couple of handy channels. Are you running the latest scanner version? If yes, can you please get an info log and send it to support and ask them to see if they have those channels mapped out.

  7. #27
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    I am running 4.8.7. for the software.

    The Offset vs Injector tip temp wont be viable due to the offset select set to vacuum, correct? I haven't got this deep into tuning, i have only done base tuning to get new engines started. Please pardon my ignorance.

  8. #28
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    That's the latest.

    Mine is set to vacuum and I have used the ITT offset to help with levelling out the fuel trims on start up.

    I'm not using it on yours. Generally it is something that I'd do right at then end when everything is running good.

    If i can point you to your last log; once the idle speed reaches its final set point, the air flow remains relatively constant. The fuel trims though still move on a bit of slope until they finally settle out once everything is nice and hot. I use the colder cells of the ITT offset table to correct that slope. To do it properly you would need the wideband hooked up as you will be analysing the open loop part too. It's not necessary to do it, it's just another cure for OCD.

  9. #29
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    Ahhh, I understand your method now. Thank you for taking time to teach me and not just shut me out. Do you think this may have something to do with our two countries have different parameters for pollution standards?

  10. #30
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    Not sure man.

    For example what I would do with your tune, is once your fully warmed up you can see I've got you a little on the rich side. I would then take a bit of fuel out to get it reading 0 to -2% on the trims. This will create a leaner condition when cold and on the journey to warming up. In the scanner I would create a chart with ITT vs fuel trims and another one ITT vs OL EQ error and then combine the two to guide me which ITT offset cells need adding to.

    My tune for example has adjustment added in ITT cells from freezing up to about 30 degC. My fuel trims and open EQ error are pretty flat from cold to hot on a long idle log.

    Hope this makes sense and you can put it in your bag of tricks.

  11. #31
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    Just a note, here. It is very bad ( like drinking Jobu's rum ) to start an engine, with the sensor already heated up. If you MUST do that, to get startup data, you should use a wideband with an NTK sensor, like the Ballenger AFR500v2. The NTK sensors, while MUCH slower than the Bosch sensors, are harder to kill via thermal shock.

    The wideband sensors CERAMIC elements "warm up" to about 1450?F ( glowing orange hot ). When hit with a rush of relatively cold/wet startup exhaust, they crack, Just like throwing cold water on a hot windshield, in the sun, in summer, in Arizona. The cracks form and spread with each heat cycle. Initially, they just ruin the calibration. But, eventually, they hit something important, and the sensor flakes out, or dies, completely

    The NTK sensor elements are bigger hunks of ceramic than the Bosch units. So, they are more resistant to cracks. And it takes longer for cracks, that do form, to find something important to hit.

    The down side is that the NTK sensors are VERY slow. Thus, are not really useful for transition events; just steady-state AFR. But, usually, that is all you need for startup AFR.

  12. #32
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    Quote Originally Posted by 13capriceNC View Post
    its all good. I dont have IVT channel with the E38 on this car. I have intake air temp in the log. I wish i had the valve temp to help you out. The car is still "warm" so i will get you a log later tonight or in the morning (my time, EST).
    have u tried the latest Beta ? there was a heap of channels added i noticed in my e38 a while back, yours seems to have even less for some reason

  13. #33
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    I downloaded the Beta with no luck to find any other channels such as the IVT. Here is the latest cold start with that tune you sent.

  14. #34
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    I compared this start to your first log and the start up rpm profiles look very close.

    Based on your original post and complaint (rpm dip) can we call it good?

    Next thing, do you want to try and get rid of the start up stutter?

    You can do this yourself or I can help.
    Add another 1 gram at a time to the start-up airflow. Then try a couple of iterations.
    Or revert start up air back and take cranking VE to 80 and try
    Or a mix of both table adjustments

  15. #35
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    I can try the start up issue, you have done a lot for me the past couple days and I really appreciate your help!!! if I run into a problem with it, ill let you know what I have done, but I think I can figure it out. Have to learn somehow lol. Thank you again!

  16. #36
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    Too easy man. Been good working with you.

    You definitely need to hit up HPT support to see if those extra channels can be added. Weird that they're not as a the Caprice PPV is not a unicorn.

  17. #37
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    Will do, brother. The same ECU is on the Pontiac G8s back in 2009 so I don't know why they aren't sharing same channels. Cheers!