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Possibly yes at lower openings there could be more loads on the blade...but then at lower blade openings there would also usually be less boost and airflow in general because of that smaller opening ?
Either way, log the raw voltages of both tracks and see exactly what the blade is doing. As long as you can log it fast enough, any wobbling or similar behaviour should be apparent on the logs. If the blade is moving about too much, then that could well be part of the cause.
HPTuners didn't want to do anything about this issue. I hope none of you ever get Bill Henn as the person that decides whether or not something gets modified in their software. I'm not totally sure who is in charge of the group over there but it's not what it used to be. I'm not impressed and as you pursue more power, you will find they don't offer a complete package and/or total control.
After thinking it over and discussing it with some knowledgeable friends, I decided it was time to make a change. I'll be switching to other means of tuning the car at some point but I didn't have time to make that change before the weekend.
Here's how the LS2 throttle body is typically installed because the power steering reservoir is in the way.
Here's the stock LS6 throttle body oriented in the stock direction and the LS2 throttle body installed to match.
As Jon said,"Reason #1,000,001 for owning a welding machine."
Last edited by Turbo-Geist; 04-11-2017 at 06:30 PM.
I went to the track on Sunday and made 6 passes and HPTuners REP didn't occur one time. There was even one pass where the car spun hard and I was on and off the throttle and REP wasn't triggered.
I didn't get a chance to really turn the boost up on the launch but the boost controller was set to the same settings that caused issues a couple of weeks ago when testing on the street.
I plan to go back soon and get really aggressive with the boost ramp during launch to see if this has solved the issue 100%.
Possibly yes at lower openings there could be more loads on the blade...but then at lower blade openings there would also usually be less boost and airflow in general because of that smaller opening ?
Either way, log the raw voltages of both tracks and see exactly what the blade is doing. As long as you can log it fast enough, any wobbling or similar behaviour should be apparent on the logs. If the blade is moving about too much, then that could well be part of the cause.
I am able to build boost very quickly with the current turbo kit. We are talking about issues with milliseconds here.
Example:
Blade is at WOT, full boost during the launch and then the tires start to spin. You pedal the throttle and because of the factory programming, the computer decides to go to 25% even though you commanded 75% with your left foot.
In that brief moment, the blade is at 25% and pressure forces are high enough to get it going towards the closed position. Your foot is commanding more, but the computer sees the blade is closing and says party over. REDUCED ENGINE POWER MODE
When you flip the throttle back to the stock orientation and the airflow is biased above the centerline of the pipe, it naturally wants to flow over the top of the throttle blade. There isn't the sharp angle of attack that is similar to wind pushing on a sail.
Your REP mode is more than likely restricting blade to 25% max though.
It isnt that the blade is going to 25% prior to REP occuring. The 25% is because of REP
If everything is working correctly, the blade can only go where the ecu has been programmed to move it to. I assume HPT does allow the user to define blade position vs pedal position ?
And things like HPT can never give total control, they can never give a complete package. Simply because the hardware was never designed for what everyone is doing, so the software will always be restricted by what the hardware can allow and what the coders can actually make it do.
In many ways for those choosing that route, you are lucky it is coping with as much as it does.
And to now...the only change you made was flipping the TB over ? Same TB ?
No, the blade actually closes more than you want it to based on some logging that I did. It seems the ECM is trying to predict where it thinks the throttle needs to be. A feedback/predictive loop if you will. The problem is it's conservative and doesn't fit what a performance enthusiast would want.
It will go to 25% throttle when the pedal is at 75% just sitting in the car with key on engine off
HPT doesn't give the end user access to all of the throttle parameters to specify blade position vs. pedal position. This is what I wanted. They said NO.
Yes, the only change was flipping the throttle body. I'm still using the same one. It didn't make sense to introduce another variable.
Sooooo then I was right about boost pressure and the throttle blade?,Is that what your saying?????? Have a nice day
I think we had similar messages. You were saying the boost was moving the throttle blade past 100%? The stock LS2 throttle body won't physically go beyond 100% open unless it is damaged. My thoughts were that it was being forced toward a closed position at part throttle conditions when the driver is trying to quickly recover from tire spin.
Either way, I'm glad you provided input and there might finally be a solution. I won't consider it 100% solved till I turn up the launch CO2 pressure and really test it out.
Originally Posted by DRIVER456
Also before yesterday,Did you mention the TB was mounted upside down? I don't feel like reading everything again.
I posted a video showing the blade opening from the top outward. It may be a stretch, but I thought most C5 owners mounted the LS2 throttle body with the motor pointing towards the passenger side. This is the way it was mounted on a stock LS2 corvette, also.
I rotated it to where the blade opening direction now matches the stock LS1 and LS6 throttle body. I never paid attention to the way either throttle body opened until this issue surfaced. The computational flow dynamic model examples posted above seem to support what could be occurring.
No, the blade actually closes more than you want it to based on some logging that I did. It seems the ECM is trying to predict where it thinks the throttle needs to be. A feedback/predictive loop if you will. The problem is it's conservative and doesn't fit what a performance enthusiast would want.
It will go to 25% throttle when the pedal is at 75% just sitting in the car with key on engine off
HPT doesn't give the end user access to all of the throttle parameters to specify blade position vs. pedal position. This is what I wanted. They said NO.
Yes, the only change was flipping the throttle body. I'm still using the same one. It didn't make sense to introduce another variable.
But again, under many conditions that could be normal. The whole point of DBW is that the "tuner", in this case GM etc can make the blade do things other than simply mirror the pedal.
Lots of OEM cars with that setup have a torque demand map, which then relates to a blade position map based around torque requested by the driver...ie pedal position.
So just because you have your foot at 50%, doesnt mean the blade will always be at 50%, likewise for almost any throttle opening.
You might go 100% WOT at say 3000rpm...but GM knows the engine makes more torque at say 50% blade opening, so it will only open it that far, gradually ramping it up as rpm's rise. Which makes sense, as by putting your foot down 100%, you have asked the engine to pull it's hardest so the programming will do that, even if the blade isnt doing what your foot says.
And Key on engine off, there is no real need for the blade to ever go 100% so it wouldnt be unusual for blade movements to be restricted until the engine is actually running
It can all result in some very complicated mapping ! Hence you cannot really compare pedal position vs blade position and say one is wrong, without actually knowing requested blade position vs actual blade position.
Whilst you may not have access to those tables, I'd be surprised if you did not have access to log the data necessary to see if things are working as expected, as that would be fairly routine for diagnosing such faults via OBD or whatever live data is available.
Last edited by stevieturbo; 04-12-2017 at 03:09 PM.
This is all getting crazy off topic. The point to get across here is that even with same throttle, air mass flow biases to the top of the throttle opening. So if throttle is positioned for blade to open towards flow on top then it tries to close and successfully overcomes torque being applied by throttle. When flipped, the pressure may try to keep the throttle further open than commanded, but doesn't appear to cause REP.
04-11-2017, 06:04 PM
