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  1. #31
    Junior Member Landrew's Avatar
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    Hi all - I have a manual 2015 C7 Z06 that has a throttle lag issue. It does not happen when accelerating through the gears, whether from a standing start or otherwise. It happens when going at a steady speed in OTHER than 1st gear, and mainly at lower rpm (under 3500). It is perhaps a half second lag and then power comes on strong. If I just feather the gas before standing on it, it does not seem too bad. OF course when the power does come on it's crazy fast and hard to keep the tires from getting loose. Could this be a TSB issue? It feels like a throttle response/drive by wire issue. Did not happen on any other car I have had including Vipers, a VW GTI with a turbo, 91 ZR1, etc. Any ideas? I have been living with it and have not asked the dealer yet. Do love the car otherwise. Thx.

  2. #32
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    Welcome to our forum Landrew. Here is where you will find info re TSB et al https://www.stingrayforums.com/forum/tsb-recalls/. Perhaps one of our Z06 owners will be able to chime in as well.
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  3. #33
    Member Guitar Man's Avatar
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    I wanted to chime in with my experience with my supercharged (Edelbrock E-Force) 2014 M7 base Stingray, so non-Z06, and the Vitesse throttle controller. This thing generates dramatic opinions with a lot of people, so please read what I have to say and keep calm....please. I love it. When I installed the Edelbrock E-Force the power was awesome, but modulating the throttle smoothly was close to impossible. Once you’re going 50-60 mph you can nail it and fly off, but trying to get a quick, smooth start without doing a 360 breaking the tires loose was nigh impossible. I experimented with all the various modes (Eco tended to be the smoothest), but nothing was great. Then I bought the Vitesse, not to get quicker response but to slow it down! Cutting to the chase I run it at Eco 4 with the Car mode in Sport (I don’t use the Vitesse’s Sport mode to sharpen response) and I can drive the car faster and smoother, and get 1-2 MPG better mileage as well. Of course it doesn’t make your car faster or fix dead spots (though I never noticed one in mine), but it does make the throttle more linear, more predictable, smoother. And that translates into faster driving....I hope this makes sense the way I laid it out.

    I know my car is not a Z06 so these comments aren’t completely apropos to this thread, but I wanted to share my experience, this has made a huge difference in my driving pleasure!

    Thanks for reading this far everyone!

    Steve
    Last edited by Guitar Man; 01-01-2019 at 05:11 PM.

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  5. #34
    Senior Member Fireeagle's Avatar
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    Steve, great job explaining what you did and how you have solved the problem.
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  6. #35
    Senior Member twowinns's Avatar
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    I don’t have a Z06, but the Vitesse and a ported throttle body combined has made a huge difference in my Stingray.
    2014 Stingray Coupe, Lime Rock Green, 3LT Brownstone, A6, NPP

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  7. #36
    Junior Member Landrew's Avatar
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    Thx guys I think I will check it out further when the weather is better up here in the NE. I went thru the TSBs and did not see anything. I will also see what happens if I go at a steady 4000 rpm and then accelerate. It almost seems like I need to make the supercharger boost begin to move from - to = or + by barely pressing throttle and then accelerate to get no lag. Maybe at 4k it's different. At worst a trip to the dealer is in order. The lag happens in all settings including track. May test drive a newer z06 to see if it occurs there too. Weird thing is that in frst gear there is never any lag and shifting thru gears results in 0 lag as well.

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    Senior Member Boomer's Avatar
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    Quote Originally Posted by Landrew View Post
    Thx guys I think I will check it out further when the weather is better up here in the NE. I went thru the TSBs and did not see anything. I will also see what happens if I go at a steady 4000 rpm and then accelerate. It almost seems like I need to make the supercharger boost begin to move from - to = or + by barely pressing throttle and then accelerate to get no lag. Maybe at 4k it's different. At worst a trip to the dealer is in order. The lag happens in all settings including track. May test drive a newer z06 to see if it occurs there too. Weird thing is that in frst gear there is never any lag and shifting thru gears results in 0 lag as well.
    I don't think your're gonna get it fixed by by seeing "what happens if I go at a steady 4000 rpm and then accelerate".


    "May test drive a newer z06 to see if it occurs there too."


    Sounds like some diagnostic needs to be done. If the problem compares to the other Z06s you drive, you should sell your car.
    Last edited by Boomer; 01-03-2019 at 05:58 PM.

  9. #38
    Senior Member STINGmole's Avatar
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    Is this in sport or track mode?

    I'm guessing it takes a second or two for stabilitrack to decide whether it wants to let you put the car in a ditch...or not.
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  10. #39
    Senior Member Manta-C7's Avatar
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    triplekg, that has been my issue w/ this car since test driving at the dealership. I've tried the Vitesse TC, diablosport tuner, and arguably the three most talked about ported throttle bodies out there. I have also combined some of the above w/ some success but still not enough. One just needs to hop into almost any other car to feel they respond better.

    After spending so much time/money, and being and engineer by trade I decided to take it upon myself to find out, I also have all the equipment needed at work (measuring, testing, simulating, machining etc.)

    Long story short; it is the throttle body. Between idle (~5 degree throttle) to ~30 deg throttle angle the amount of mass air flow (which is proportional to power) puts our C7 at a weigh to power ratio similar to that of trucks and SUV’s, both in terms of absolute value and rate of change. Not to be confused w/ the weight to power ratio that is usually published, which is calculated at WOT, above 35 deg throttle angle our C7’s shine. It is on the part throttle range (idle to 30 deg) that the issue exists.

    I’m not going to speculate on the reasons, but I can tell you that our throttle body p/n is used in many GM vehicles and that such throttle response helps w/ fuel economy. That helps to keep parts cost low and meet EPA requirements for the fleet. However, I do not think one size fits all and that a sports car needs to sacrifice performance for economy.

    The Vitesse TC and the tune improve response by making the throttle plate move faster between the 5-30 deg range. Faster, but it still needs to go through a tortuous path for the air flow, and the manifold pressure doesn’t recover as fast. It is a transient process, and it is from the intake manifold where the pistons suck the air from. Notice that this is not true throttle response, it is just tricking the ECM into thinking you have pushed the accelerator pedal harder. The actual throttle response is the same, only physical changes to the throttle can make for a true throttle response.

    The existing aftermarket ported throttle bodies also helped, they do change the throttle physically, but their effect only starts to take place at about 25 deg in what I thought was the best one of them. Definitely a step in the right direction, but I noticed they were not optimized and that more could be extracted from them, that is a throttle body that can increase the absolute value and rate of change of mass air flow right from idle and up to 35 degrees to achieve the same weight to power ratio (in that range) of similar sports cars that feel nimble and fun to drive at part throttle.

    Another long story short, I reversed engineered 10ea C7 OEM throttle bodies, 3ea C7 aftermarket ported throttle bodies, and a benchmark (competing make/model) OEM throttle body. Optimized/modified the C7 OEM throttle body to meet the benchmark throttle response as well as the goal stated above.

    The modified throttle body has been in my C7 since September, works beautifully, no codes, no issues. Driven in different conditions/modes for a few thousand miles now, just waiting for a hard freeze to see how it does on cold weather, it also needs to be tested at high altitude and in different C7 models to make sure it works in all cases.

    If you want, I can send you a modified throttle body for you to try at no charge (yours to keep) and at your own risk. It is made from a brand new OEM throttle body. Just need your feedback in exchange. I’m very interested to see how it does in a Z06. All I can say is that is works great on my C7-A8 and that you will be able to feel and measure the difference w/ a simple scan/stream data tool.

    I have attached a few pics of both the OEM and the modified throttle bodies, I cannot disclose much more at this point. Hope they help you understand what I’m talking about.

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    Last edited by Manta-C7; 01-07-2019 at 10:42 AM.

  11. #40
    Senior Member rdslon01's Avatar
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    I just got back from a trip to the Silicon Valley which started on Jan. 6. I can't say anymore that I haven't made a design mistake which required me to be in the lab since August 2015. Ugh... It is time to restart the clock.

    Anyway, while there I had a Nissan <whatever> rental car. I just Googled Nissan's website, and <whatever> must have been either an Altima, Maxima, or Sentra. I don't know, and don't really care which it was.

    The point is that while driving it I thought of this thread. You see, that silly little Nissan was blazing fast on initial start from a stop (like when pulling out from a red light). It was so quick and nimble; I am just not used to that coming from the agonizingly slow starts with Caroline.

    What a shame.
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    Rodney and C.A.R.O.L.I.N.E. (Candy Apple Red, Outrageously Lovely, Incredibly Nimble Entertainment)

    C.A.R.O.L.I.N.E. is a 2016 Long Beach Red, 3LZ, Stage 1, Z06 Coupe with an Automatic 8-speed transmission, the Spice Red Design Package, Competition Seats, a Carbon Flash Hood Stinger, and a Body-Colored Dual Roof Package. She has SunTek paint protective film installed on every painted surface other than on some of the vents' and grille's slats, G3 Carbon's "G3-O7" side skirts, GM StingRay Red Tail Lights, GM Rear Splash Guards from Trunk Monkey, ACS Composite Enhanced Front Wheel Mudflaps from West Coast Corvette, and her mufflers painted with POR15 Aluminum high temperature paint.

  12. #41
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    Quote Originally Posted by rdslon01 View Post
    I just got back from a trip to the Silicon Valley which started on Jan. 6. I can't say anymore that I haven't made a design mistake which required me to be in the lab since August 2015. Ugh... It is time to restart the clock.

    Anyway, while there I had a Nissan <whatever> rental car. I just Googled Nissan's website, and <whatever> must have been either an Altima, Maxima, or Sentra. I don't know, and don't really care which it was.

    The point is that while driving it I thought of this thread. You see, that silly little Nissan was blazing fast on initial start from a stop (like when pulling out from a red light). It was so quick and nimble; I am just not used to that coming from the agonizingly slow starts with Caroline.

    What a shame.
    Wow, really hard to believe that with all the power in your Z06, your perception is that the Nissan was 'blazing fast' from a stop. I have never driven a rental Nissan that was faster from a stop than RedHot. Having not stomped on a Z06 accelerator pedal I don't have a first hand comparison. I certainly would be disappointed and want my Z06 checked out. Please note: I am not doubting you, just amazed at this.
    Last edited by jsvette; 01-14-2019 at 04:59 PM.
    aka Jeff
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  13. #42
    Senior Member rdslon01's Avatar
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    Quote Originally Posted by jsvette View Post
    Wow, really hard to believe that with all the power in your Z06, your perception is that the Nissan was 'blazing fast' from a stop. I have never driven a rental Nissan that was faster from a stop than RedHot. Having not stomped on a Z06 accelerator pedal I don't have a first hand comparison. I certainly would be disappointed and want my Z06 checked out. Please note: I am not doubting you, just amazed at this.
    I am pretty sure, based on other Z06+A8 owners' responses in this and other similar threads, that it is functioning as designed. Also, for me, the lag goes away in Sport and Track modes. It is just that I want the smoother ride provided by Tour, so, most of the time, I just deal with the horrible lag that goes with Tour mode. Also, after my Z06 gets going, it is SCREAMING FAST if above about 15 MPH and 3000 RPMs (I am approximating). It is just getting it going from a dead stop at idle RPMs that is the problem. I suspect it is the nannies in Tour trying to eliminate wheel spin, and the engineers who programmed it went much too far with reigning it in. They could have numbed it down tremendously, and still not gone nearly as far as they did.

    I wonder if GM fixed this in the 2018s and/or the 2019s. I don't think I have heard of anyone with those model years complaining...
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    Rodney and C.A.R.O.L.I.N.E. (Candy Apple Red, Outrageously Lovely, Incredibly Nimble Entertainment)

    C.A.R.O.L.I.N.E. is a 2016 Long Beach Red, 3LZ, Stage 1, Z06 Coupe with an Automatic 8-speed transmission, the Spice Red Design Package, Competition Seats, a Carbon Flash Hood Stinger, and a Body-Colored Dual Roof Package. She has SunTek paint protective film installed on every painted surface other than on some of the vents' and grille's slats, G3 Carbon's "G3-O7" side skirts, GM StingRay Red Tail Lights, GM Rear Splash Guards from Trunk Monkey, ACS Composite Enhanced Front Wheel Mudflaps from West Coast Corvette, and her mufflers painted with POR15 Aluminum high temperature paint.

  14. #43
    Senior Member Manta-C7's Avatar
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    Before the C7 I had a Subaru BRZ, then a VW GTI and I felt the difference in throttle response since day one. Both the BRZ and the GTI felt smaller, nimbler. But; how come? The C7 has more than double the HP and it is lighter, not to mention the Z06. For years, I thought it was in my head, until I calculated ( from measured data) the weight to power ratio at part throttle of the C7, then went into a 375 HP/ 5700 lb SUV and did the same. The weight to power ratios were the comparable and felt comparable (200-300 lb/HP) at part throttle. Then, I knew it was real.

    All C7’s use the same TB (not sure about the ZR1), you would be amazed of how many GM models use this TB p/n. Yes, it is on purpose, and probably works as designed. I’m sure GM or Delco could have made a fun one specifically for the C7, but then the economy of scales and fuel economy ~30 mpg for a 6.2L V8 would not be there.

    Switch the nannies off and see if you feel any difference. At least I don’t.

    I’ve also added below a plot of the minimum measured performance of the modified throttle bodies. The fun factor seems to be on the rate of change (slope/gain of curve) from idle (5 deg) to 25 deg. The plots look very similar (a matter of scaling) but the mass air flow gains tell a different story:

    OEM: 1.2 grams/sec-Deg (Baseline)

    Best Aftermarket: 1.5 grams/sec-Deg (25% Increase)

    Modified/Optimized: 2.3 grams/sec-Deg (92% increase)

    BTW, after about 35 deg they all perform the same, I find the WOT HP gain claims from some aftermarket PTB’s hard to believe.

    Name:  8-Perf Plot.JPG
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    Last edited by Manta-C7; 01-15-2019 at 08:12 AM.

  15. #44
    Senior Member Henry427's Avatar
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    Quote Originally Posted by rdslon01 View Post
    I am pretty sure, based on other Z06+A8 owners' responses in this and other similar threads, that it is functioning as designed. Also, for me, the lag goes away in Sport and Track modes. It is just that I want the smoother ride provided by Tour, so, most of the time, I just deal with the horrible lag that goes with Tour mode. Also, after my Z06 gets going, it is SCREAMING FAST if above about 15 MPH and 3000 RPMs (I am approximating). It is just getting it going from a dead stop at idle RPMs that is the problem. I suspect it is the nannies in Tour trying to eliminate wheel spin, and the engineers who programmed it went much too far with reigning it in. They could have numbed it down tremendously, and still not gone nearly as far as they did.

    I wonder if GM fixed this in the 2018s and/or the 2019s. I don't think I have heard of anyone with those model years complaining...
    Rodney, I'm curious if you took your Z06 to the dealer for the suspension software upgrade. Those that did report a smoother ride in Sport mode. Of course it doesn't fix the lag problem but it might make it more comfortable to leave the suspension in Sport.
    rdslon01 likes this.
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  16. #45
    Senior Member rdslon01's Avatar
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    Quote Originally Posted by Henry427 View Post
    Rodney, I'm curious if you took your Z06 to the dealer for the suspension software upgrade. Those that did report a smoother ride in Sport mode. Of course it doesn't fix the lag problem but it might make it more comfortable to leave the suspension in Sport.
    No, I haven't done that yet, Paul.
    Rodney and C.A.R.O.L.I.N.E. (Candy Apple Red, Outrageously Lovely, Incredibly Nimble Entertainment)

    C.A.R.O.L.I.N.E. is a 2016 Long Beach Red, 3LZ, Stage 1, Z06 Coupe with an Automatic 8-speed transmission, the Spice Red Design Package, Competition Seats, a Carbon Flash Hood Stinger, and a Body-Colored Dual Roof Package. She has SunTek paint protective film installed on every painted surface other than on some of the vents' and grille's slats, G3 Carbon's "G3-O7" side skirts, GM StingRay Red Tail Lights, GM Rear Splash Guards from Trunk Monkey, ACS Composite Enhanced Front Wheel Mudflaps from West Coast Corvette, and her mufflers painted with POR15 Aluminum high temperature paint.

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