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Thread: 2015 Cruze 1.4t. Hard boost cut, what tables control that?

  1. #1
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    2015 Cruze 1.4t. Hard boost cut, what tables control that?

    I realize ideally I should be posting up at tuning a log I just don't have my computer handy at the moment be able to do so. The issue that I'm having is after to my car recently I seem to be hitting a hard boost cut. Most of the time it happens around 3,600 to 4000 RPM and it feels like I just let my foot completely off the gas. But say in 1st gear I'll go to part throttle it it ramps up and then cuts out at like three thousand so it seems to be either an air mass based cut off or a boost based cut off at least as far as I can tell. I'm not sure what else would cause it. For a cruise I'm fairly heavily modified but haven't had a problem with these mods before so I'm thinking it has something to do with the way my tune is but I'm just not sure what it is I have no internals and the stock Turbo and no methanol injection but I have pretty much everything else you can get for the car. 60lb injectors catless downpipe catless midpipe ported intake manifold intake zzp aftermarket intercooler and charge piping hptuners obviously and I've also played with the cam timing quite a bit which normally hasn't affected anything but I'm thinking it may be a mechanical issue as far as the Boost cut going where I don't know maybe I'm having a boost leak faulty wastegate I'm just not sure where to start looking so if anybody can point me in the right direction I'm just at a loss at the moment

  2. #2
    Quote Originally Posted by RoninDusette View Post
    I realize ideally I should be posting up at tuning a log I just don't have my computer handy at the moment be able to do so. The issue that I'm having is after to my car recently I seem to be hitting a hard boost cut. Most of the time it happens around 3,600 to 4000 RPM and it feels like I just let my foot completely off the gas. But say in 1st gear I'll go to part throttle it it ramps up and then cuts out at like three thousand so it seems to be either an air mass based cut off or a boost based cut off at least as far as I can tell. I'm not sure what else would cause it. For a cruise I'm fairly heavily modified but haven't had a problem with these mods before so I'm thinking it has something to do with the way my tune is but I'm just not sure what it is I have no internals and the stock Turbo and no methanol injection but I have pretty much everything else you can get for the car. 60lb injectors catless downpipe catless midpipe ported intake manifold intake zzp aftermarket intercooler and charge piping hptuners obviously and I've also played with the cam timing quite a bit which normally hasn't affected anything but I'm thinking it may be a mechanical issue as far as the Boost cut going where I don't know maybe I'm having a boost leak faulty wastegate I'm just not sure where to start looking so if anybody can point me in the right direction I'm just at a loss at the moment

    Can you post your tune. I have pretty much the exact same setup as you.

  3. #3
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    Quote Originally Posted by Jeff7577 View Post
    Can you post your tune. I have pretty much the exact same setup as you.
    With the injectors too? Do you have the same problem?

  4. #4
    Yeah I?m using 60lb injectors and it?s working good.

  5. #5
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    Quote Originally Posted by Jeff7577 View Post
    Yeah I?m using 60lb injectors and it?s working good.
    here ya go.**deleted**
    Last edited by RoninDusette; 07-17-2020 at 06:17 PM.

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    Quote Originally Posted by Jeff7577 View Post
    Yeah I?m using 60lb injectors and it?s working good.
    Hoping you can answer back fairly quickly. This has been a thorn in my side for a minute. It has a hard start issue where it like, sputters and is undrivable until it idles for a few minutes, then it's fine. Then there is the boost cut issue. I never had that up until recently, and I am thinking it's my cam timing, but its just a flat out hard cut (and the only place I messed with the cam timing was at wot, so that wouldn't mess with the cold start.). I am just tired of logging and tuning it for now. I want to turn my fuel savers back on (dfco, cfco, etc). Currently running e85 as well (79.9%, to quote my ff sensor).

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    Great. Finally get someone to respond and then they duck out. lol

  8. #8
    I'm going to look at your tune today.

  9. #9
    You have changed a lot, probably more than necessary. Try increasing Overspeed limit minimum. Are you hitting your boost targets? I'm running 25 psi atm and had to greatly increase my wastegate DC to get there. On the scanner is the throttle actually closing with the pedal at WOT?

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    Well a lot of what I changed I have been working in for a year. It's the culmination of many months using it, going back to stock, taking the good stuff from the other tunes and applying it there and starting off at that point. The torque and DD swttings I have been using almost exactly like that for a long time with no issues. Though, I haven't aged with the waste gate DC (I don't fully understand it so anything you can explain would greatly help). I don't have my computer in front of my to check logs so I'll post again in a few after I check a log where it happens, but it sure as hell feels like it's closing. In first gearnit will do it at a lower rpm if I romp on it and second and third and up it does it higher rpms so I'm pretty sure it's somethibg torque it airmass relates that is just saying 'nyyyoooooope! '. Just not sure what would be causing that at this point. How does my fuel settings look for these injectors? I've gotten it right a few times using this spreadsheet I found that a lot of people swear by. Somewhere along the line I'm changing something that ends up making it fall in its face from like 2600 to 3200. It doesn't do that right now but I'm still wondering what causes it.

  11. #11
    Quote Originally Posted by RoninDusette View Post
    Well a lot of what I changed I have been working in for a year. It's the culmination of many months using it, going back to stock, taking the good stuff from the other tunes and applying it there and starting off at that point. The torque and DD swttings I have been using almost exactly like that for a long time with no issues. Though, I haven't aged with the waste gate DC (I don't fully understand it so anything you can explain would greatly help). I don't have my computer in front of my to check logs so I'll post again in a few after I check a log where it happens, but it sure as hell feels like it's closing. In first gearnit will do it at a lower rpm if I romp on it and second and third and up it does it higher rpms so I'm pretty sure it's somethibg torque it airmass relates that is just saying 'nyyyoooooope! '. Just not sure what would be causing that at this point. How does my fuel settings look for these injectors? I've gotten it right a few times using this spreadsheet I found that a lot of people swear by. Somewhere along the line I'm changing something that ends up making it fall in its face from like 2600 to 3200. It doesn't do that right now but I'm still wondering what causes it.
    What injectors are you using specifically? If you post your stock tune I will make a tune using some of my settings as a starting point and you can see how that works.

  12. #12
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    So, I am almost positive I know what it is. My boost is waaaayyy above where it should be. I have it set for 240 kpa, where it usually is, and it's regularly hitting 260 kpa and higher. You can see in this picture where I let my foot off just after this because I hit this wall. I am also running e85 and not getting any kr whatsoever, and the throttle stays open completely until I let my foot off, so I am thinking it's some sort of overboost protection maybe? I also have a forge wga (which I am going to inspect in a bit. I also heard a fast clicking coming from under my hood when I am getting ready to start the car, and I am willing to bet it's my boost controller. I don't know why, but I feel like out of control boost, and that clicking are related.


    and here is the log from it.

    Also, yes. I would love it if you can give me the correct injector/fuel settings for my ride. That would help a lot. I have the siemens deka 60# injectors and am running e85. Rest of the fuel system is stock (well besides the obvious FF sensor). Here is my stock calibration.

    Thanks again for your help
    Attached Images Attached Images
    Last edited by RoninDusette; 07-21-2020 at 01:26 PM.

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    Quote Originally Posted by Jeff7577 View Post
    What injectors are you using specifically? If you post your stock tune I will make a tune using some of my settings as a starting point and you can see how that works.
    I mean, when I first plugged in the data for this tune everything was fine. I was just gradually trying to add a little more power and get my idle straight. Whatever you got for fueling with those injectors I will try

  14. #14
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    When looking at that screen shot again it's hitting a fuel cut. Right before I let off the gas there is a hard fuel cut (check the idc). I immediately let off the pedal after it happened. I must be running way too rich or something as I have never ran out of fuel this low of torque with these injectors. Probably the over boosting

  15. #15
    I haven?t looked at your log yet but I?m guessing it?s boost pressure. I have the forge wastegate actuator but I?m using the stock atm. Because of the spring pressure in the forge unit you actually need to lower wastegate dc to prevent overboost. I log Desired and Actual pressure ratio against RPM and raise/lower the Base DC table in that area as necessary.

  16. #16
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    Quote Originally Posted by Jeff7577 View Post
    I haven?t looked at your log yet but I?m guessing it?s boost pressure. I have the forge wastegate actuator but I?m using the stock atm. Because of the spring pressure in the forge unit you actually need to lower wastegate dc to prevent overboost. I log Desired and Actual pressure ratio against RPM and raise/lower the Base DC table in that area as necessary.
    Tghat is what I am thinking too. Do you think I could borrow your graph for it? Lol. That is probably the cause of all of these issues except the cold start one. I still cannot figure that one out. That log should actually have my cold start, too.

  17. #17
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    Quote Originally Posted by RoninDusette View Post
    Tghat is what I am thinking too. Do you think I could borrow your graph for it? Lol. That is probably the cause of all of these issues except the cold start one. I still cannot figure that one out. That log should actually have my cold start, too.
    If you look at that log, the beginning is me starting the car. I am thinking I need more spark advance in the cold cranking area. If that is the case, where would I actually add that?

  18. #18
    This is your tune with my injectors settings. Some times it sputters a little after starting, especially hot restarts but only for a few seconds. They run at such a low PW at idle.
    Last edited by schpenxel; 07-21-2020 at 05:00 PM.

  19. #19
    Your wastegate DC is going to be a lot different from mine. I will make a tune for you later but I have tried to change as little as possible on mine. Try my injector settings and let me know how they work.

  20. #20
    Keep in mind that will mess up any VVE tuning you have done. I still have mine stock and it fuels accurately.