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So I took the car for a long spirited drive to ensure the tires were as warm as I can get them without doing a burn out. It feels completely normal to me again. The day all this came about it was 46 degrees, the tires were cold the roads were cold and the only explanation I can muster is that it was going in and out of traction control so swiftly and quickly back to back the only thing I noticed was there was somewhat of a power surge. Haven't changed gas, haven't changed modes or settings either....
On a side note, anyone have simple steps how to access the horsepower display? I've cycled through everything and can't seem to find it.
There's a HUGE difference in this car between rolling on the gas hard and flat out FLOORING it. Even with my MPSS nice and warm after a 50+ mile drive on a 60 degree day and having "gotten on it" a bunch, if you really flat out floor it and the supercharger gets spooled and you get the torque...it will get loose. 60mph in 2nd for me the first time. If you roll into the gas smoothly and not as hard or don't reach full throttle, I've found I can keep traction really well...something I learned with an 80s turbocharged Porsche which is really on/off with boost if you aren't smooth with the throttle. It would mean possibly slightly slower acceleration, possibly depending on how long your roll into the power was. But 80% throttle and full throttle in this car are very different.
If your tires are that old and it's a 2015 on Cup 2s, they are due for replacement as has been mentioned. Over time tires lose what makes them soft and pliable as it outgasses. It's why older tires show dry rot eventually. For best traction, you should replace them. If you want to drive year round, the AS3+ is available and you can enjoy the cold dry weather days even more. I have a second set of wheels inbound for mine and the tires waiting for them. Then summer one set and winter another.
If you think it's the supercharger coolant you should check for the air bubble. My new 2019 has no discernible air bubble in the tank and from reading others finding air above that in the supercharger itself, if you drive on the track you can get cavitation which can lead to overheating. Never heard that with mine. I do agree it's got a tiny bit of lumpy at idle, but outside of some really luxo cars with mid sized engines, most vehicles I've been in experience a little bit of that.
Front tires, ESPECIALLY in cold and with your older tires, you'll get LOTS of hopping in low speed tight turns. Ackerman effect. Never felt the rear doing it, but if you are, definitely check that out. Mine does it coming out of my driveway onto the street and I can tell it gets better with warmer tires, but never goes away. As old as your tires are, it might not go away.
Originally Posted by dxbtune
Thanks for the input, Dave. I rolled on the gas pretty hard but certainly not mashing the gas. I felt as though there was a small surge and it led me to believe the traction control was kicking in. Seeing it was cold and I am doubting my tires at that point. Turning off traction control and giving it a go was not the right approach.
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Like anything new, you notice everything on a vehicle and wonder if it is normal or not. It's a learning curve, have 100,000 warranty on the car with 3 years drivetrain left and I purchased the extended 150,000 mile warranty so I'm covered but still, it's interesting to learn what's actually going on...
Here are a few to share that I've noticed in the past 2 weeks of owning the car:
*Engine vibrates at idle (apparently GM tuned it that way to represent the homage of the earlier corvettes) oh ok.. well I would rather bump it up 200 RPM at idle and have it smoother.
*Eco mode in the auto jerks the car unless in paddle shift, M7 like mine only if in eco so I won't be going there nor do i want to.
*Heard swashing sounds behind the dash when starting it up (apparently, that's water going into the supercharger cooling channels and another version is that it's the oil going back into the tank since it is dry sump) normal sounds.
*Car takes time to fire up when cold. ( fuel lines pressuring up needs a few revolutions to get it right then you get a spark) normal delay
*Car makes popping sounds/jolts on tight turns (rear end needs oil with a synthetic blend increase lubricity etcetc) normal and is actually in the owners manual to not bring it in for service....
This is great information and makes a whole lot of sense. Confirmed nothing from the rear, only the front. Car pulls strong no issues. The water sound I was hearing is definitely the oil tank front right of the car. Found information on the tank filling up after sitting for a while or while cold. I am confident that everything is as should be. Appreciate the tire recommendation.
The car is at the dealer getting the high pressure fuel pump changed.
Put the car on the dyno and did some diagnostics assuming they did a pull too. Found that the pressure was only 2000psi. Power curve was not smooth (see picture) fuel pressure regulator code popped up. Tech told me the car was not getting much boost either...
Brought the car to the dealer and going to fix it under warranty.
I knew something was up despite not getting a code...
Good you didn't believe that traction control is magical. It is not. Normally the car will step out quite a bit and you will notice it abruptly intervene. When you get the car back, if you want to see magic try the PTM modes.
posted this on another thread but just wanted to update for anyone following....
"I called the service advisor and gave him the TSB for the issue https://gm.oemdtc.com/TSB/SB-10059036-2458.pdf
He said that was the first thing the tech checked and it was fine. They ordered a new HPFP and some other miscellaneous parts including the supercharger gasket. Parts arrive Wednesday, hopefully, I will get the car back Friday. Since they took off the supercharger I hope they change everything associated with the fuel system such as the fuel pressure regulator and the fuel pressure sensor just to be safe. The last thing I need is to have the exact same issue and bringing it back. Service adviser stated the HPFP "just went bad"
If you want to see how well the traction control works, go out to the wet skid pad and turn the computer off and try a few donuts, it's great fun. Now turn it to WX mode and try it again.
T Changed the pressure sensor. Notes in pic.
I pushed the car a little today and felt a little hesitation. Released the throttle, will put on dyno and log the data. Curious on pressures on both the rail and the low pressure fuel pump.
Put the car on the dyno to datalog while I get the hesitation. lpfp pressure was low 59psi and the high pressure was around 2700psi. Took the car to the service department and provided them with the info. Hopefully replacing the lpfp will solve this problem. Attached the data and some screenshots.
They changed the LPFP and crossover pipe. Car runs smoother and much stronger/responsive. Haven't taken it up to high speeds as it was rush hour will report back if it's not solved.
Last edited by dxbtune; 01-23-2019 at 08:20 PM.
Reason: Edited picture
According to crazy Mike, maybe you saw his past posts on this topic, he will tell you it is not fixed. It will stop working again running hard under cold outside temperatures. If that happens he would like to hear about it. I will send you a PM. If he is right, dealer is just throwing parts at it. It will be interesting to see your results. If you ran it today its pretty cold where your at, but next few days looks like you warm up pretty good. Lucky you.
According to crazy Mike, maybe you saw his past posts on this topic, he will tell you it is not fixed. It will stop working again running hard under cold outside temperatures. If that happens he would like to hear about it. I will send you a PM. If he is right, dealer is just throwing parts at it. It will be interesting to see your results. If you ran it today its pretty cold where your at, but next few days looks like you warm up pretty good. Lucky you.
Does Crazy Mike know the fix because i'm about to go crazy myself if its not fixed...
How are you logging the data? Would be interesting if you try to run it in the 140 to 156 range while data logging, and see if it cuts out. If you get over 156 maybe its fixed.
Car got up to 148MPH today. Car is bucking, popping and just feels terrible from 125 onwards at WOT. Crazy Mike doesn't seem to be that crazy after all and might actually be onto something.....
When the traction light comes on you should let go of the gas, wait for it to go out, then step on the gas again right? Few videos I saw they floored it the whole time and TC eventually went out like somehow it fixed itself, or was I doing it wrong and you can just keep flooring it?
@djnice put me in touch with someone who was able to narrow down the issues I am facing. In fact, a few others have replicated the symptoms and won Lemon Law cases so I am glad I was not losing my mind with 3 visits to the dealer and no resolve....
Nothing related to traction control...the colder temperatures compounded with my elevation are causing the vehicle to fall on its face and act erratically at WOT above 120... I am taking the necessary steps to correct this with GM and will update as events unfold. I've documented all the series of events so this is a pretty clear cut case.
When the traction light comes on you should let go of the gas, wait for it to go out, then step on the gas again right? Few videos I saw they floored it the whole time and TC eventually went out like somehow it fixed itself, or was I doing it wrong and you can just keep flooring it?
How about stability light?
Most likely staying on the gas and letting the car control it will work better. Letting off abruptly confuses the controllers. Staying on it definitely works better in PTM modes. Find a safe place on slick roads and experiment with it.
12-12-2018, 06:13 PM
