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Thread: Cold Start almost stall

  1. #1
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    Cold Start almost stall

    Only on cold starts my 2013 Caprice PPV with mild cam has started to lean out and drop RPM to almost stalling out, but recovers. I changed the plugs and coils and still no luck. Can someone look at this log attached and tell me if you see anything screwy? I appreciate all the help.
    Attached Files Attached Files

  2. #2
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    Got a tune to go with that?

    From what I can see your EQ commanded is pretty jagged, that will need a tidy up.

    I don't know for sure but your O2 sensors could be getting enabled to early. It seems that once you start to get a bit of heat into things your trims go spot on. Just as a quick random idle in the driveway test copy over the following tables in my tune if you have an E38 or E67 PCM and are running on petrol (gasoline). My tune is not set up for ethanol.

    If it still does it revert back and hopefully someone else can chip in.

    12435 Open Loop Gas Gear
    12436 Open Loop Gas PN
    12441 Open Loop IVT Gains
    12461 Closed Loop Enable ECT vs. Startup ECT
    12462 Closed Loop Enable Delay

    8-6-3_In Car.hpt

  3. #3
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    Yes, here is the current tune that is loaded to my E38. Thanks for taking time to look at the log!
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  4. #4
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    I appreciate the help, but that tune did not help with my problem. I want to rule out anything else before I start buying replacement parts, like my coils. I don't know if that is the culprit or not.

  5. #5
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    Has anyone else had trouble after Cold starting and have the RPMs drop significantly and the fuel leaning out like I am? It does this rpm drop fuel cut around 80-85 degrees of Engine Coolant temp. Can anyone look at my tune and log and let me know where to start fixing this gremlin?
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  6. #6
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    You have some very lean numbers commanded in your open loop charts. You copied the charts that hjtrbo supplied? Fixing the open loop charts, and delaying closed loop a bit?

  7. #7
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    Quote Originally Posted by NotSure View Post
    You have some very lean numbers commanded in your open loop charts. You copied the charts that hjtrbo supplied? Fixing the open loop charts, and delaying closed loop a bit?
    Yep, second that. What happened there?

    Can you please flash the attached tune (modified from your last post) and run an idle log for me please? I still strongly think it is something to do with your closed loop settings.

    Also include the following channels:
    Dynamic air flow
    Volumetric Efficiency (mg K/kPa)
    Manifold air temp

    Graczyk Caprice Tune 28 DEC 20 (1).hpt

  8. #8
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    I will get a log to you ASAP. for reference here is a video of a cold start with the dip happening around 80 degrees F on the coolant temperature. this video is not with the modified tune you sent. Its on the current tune I originally posted.

  9. #9
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    Quote Originally Posted by hjtrbo View Post
    Yep, second that. What happened there?

    Can you please flash the attached tune (modified from your last post) and run an idle log for me please? I still strongly think it is something to do with your closed loop settings.

    Also include the following channels:
    Dynamic air flow
    Volumetric Efficiency (mg K/kPa)
    Manifold air temp

    Graczyk Caprice Tune 28 DEC 20 (1).hpt
    Here is a 5min idle log after flashing the modified tune you sent. Thank you so much for taking time to help me!
    Attached Files Attached Files

  10. #10
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    That's a good video. You can tell your setup likes it a little rich. Mine used to do a similar thing.

    I cannot see any rpm dip in your last log. Does that sound right from what you see / feel at your end???

    When you have time please do another log from cold with the tune I attached. I'm tipping that your sensors will need even more time. Just curious, how far back are they installed from where the factory had them?

    Please add the following channels to your scanner list as your fuelling could do with some work. Especially your VVE at idle, its about 50% out!!!
    Mass air flow Frequency (Hz)
    Volumetric efficiency (mg K/kPa)
    Manifold air temp
    Engine run time

    Do you have a wideband?

  11. #11
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    The log I sent was when warm. I will send a cold start log tomorrow for you.

    The O2s are about 5 months old. I am only running the upstreams because I am no longer running Cats.

    For the other channels, I am not finding Manifold Air temp when searching for that sensor. The others should be no problem to get for you.

    I do have a wideband, but not wired into the MPVI2. I can send a video of the Wideband when I do the next cold start for you too. How long do you want the log to be, is 5 min long enough of an idle or would you prefer a longer duration?

    Again, Thank you for your time and effort!!! If I make it down there for Summernats '22 I owe you a shoey and case!

  12. #12
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    Lol, not out of your shoe haha, How Lewis Hamilton could take one out of Daniel Riccardo's sweaty juice boot I have no idea!

    That's ok about manifold air temp. With a cold start intake air temp will get ball park on the VVE. You'll have to dial that in later using the traditional MAF disable method.

    We can leave the wideband for now just to make it easier on you. Not a deal breaker for idle tuning.

    Just get the engine from cold to an injector tip temp of about 45 degC will do it. (You'll probs have to add that channel too)

    Just so I know I am heading in the right direction, that warm log you sent me earlier, before the tune change would it have had an rpm dip?

  13. #13
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    Well I meant we can drink out of our own respectful shoes lol

    When the car coolant is over 77-80F (25-26C) there is no dip at all. So it's only at the initial cold start for the day in cold climate weather. During our spring and summer I did not have this problem because the ECT was consistently over 75F (25C).

    I will add the injector temp and still provide you a visual of the AFR gauge just to be thorough. Again, thanks brother!!!

  14. #14
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    Ok here is the latest cold start video of the wideband with the attached log using your modified test tune you sent. I started the video and log within 2 seconds of each other so they should sync up if you wanted to watch the wideband, hear the engine and follow the log in realtime playback. there were no dips during the cold start but a non start in the beginning. I apologize, But I did not have the channel option for injector tip temperature, so I ran for another 5 min at idle. I hope this helps. Have a great day and ill talk to you later.

    -Rich

  15. #15
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    Definitely lean at light off.

    Ok, here is a +7% air flow adjustment to MAF and a +10% guess on VVE (you didn't add the channel I wanted, naughty) around your idle area and blended out to what you already have.

    There will be back and forwards with logs and tunes over the next few days getting your initial cold start right so please be patient as we get things dialled in.

    You must add this channel if you have it available:
    Volumetric efficiency (mg K/kPa)

    Graczyk Caprice Tune 28 DEC 20 (1) (2).hpt

  16. #16
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    Awesome! thank you for checking into this tune. I thought the VVE channel was in there, I am sorry if it wasn't, I will double check and get all the info you need in order to help me out. When I get this tune flashed, I will get another log to you with the wideband video supplementing the log. I understand there will be a back and forth process and I am not bothered at all. Cheers!

  17. #17
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    I looked through my channels and the only VE channel i have an option for is this one that is added to the log file. is this the correct one?
    IMG_4695.jpg

  18. #18
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    Good Morning,

    Here is the new log and video for the Caprice. It was a little rough for a cold start. I hope the data works for you. Thank you again for your time.

  19. #19
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    Started first time (just lol), nice.

    You don't have the channel I need available. Not to worry.

    MAF is good now, VVE is closer. This new tune has just a small tweak to the VVE to get it inline with the MAF just after the initial start. Have also reverted I change I made with the first tune I gave you which is the High DI Enrich switch. Have put this back to yes.

    Good luck and till tomorrow!

    Graczyk Caprice Tune 28 DEC 20 (1) (3).hpt

  20. #20
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    Sounds good! When I get home from work and the engine is cold ill get a cold start log tonight for you. I hope the wideband videos are helping out as well. Talk to you later.