01-07-13, 04:06 PM
I believe you would classify this as a shift flare; however, if I have the wrong terminology, I apologize.
Every now and then when turning at a slow speed and lightly accelerating, the engine will take off almost as though the transmission has downshifted and then it quickly upshifts a moment later. Usually I experience this when making a turn from a stop sign or a very slow (~2 or 3 mph) slow roll turn. I've never noticed it when going straight.
Any theories on what this is? I've seen transmissions have fluid issues on turns when they are close to low due to fluid being moved away from the pump; however, I can't believe I'm moving fast enough to push fluid away from the pump. Other theory perhaps is that RPMs are pulling a bit low from power steering or something and transmission is downshifted to get RPM's back up?
Anyone else experience this or just me?
01-07-13, 05:39 PM
Mine kinda jumps ay low speed. Feels like my old outlaws when the pump was going.
It's a flare. A good tune will take care of that. While running through the gears you will also notice it feels like the car has "1/2" gears where it will kind of shift and then fully shift.
01-22-13, 10:20 PM
Mine does the "1/2" gear shifting. PGA2B, What do you mean by "tune"?
An aftermarket calibration that will address the short comings of GM. Can be loaded with either a handheld device or a programmer from HP Tuners or EFI Live. Can also be from a tuning shop done on a dyno.
01-23-13, 12:06 PM
It's like a temporary spike in RPM between gears, namely the 1 -2 shift, correct?
Mine has done this and I have had it tuned by someone who has done 1,000's of cars at a local speed shop and is nationally, heck world recongized in the LSx community (and has done all my LSx cars), on their DynoJet 248C. He has said this car is one of the more tempermental cars he's had to do, even the new CTS-V's are easier... Part of the issue for me is the Spectre CAI and it's nearly doubling of the intake size (and air volume and speed it provides vs. stock), around the MAF. It seems to do it more when it's cooler out too. I've just learned to live with it for the most part, but if it's happening often, I do an idle re-learn. Anyway, he explained alot to me about the MAF and the calculated torque torque tables it goes through based on it's readings. Now add in this larger Spectre intake, even sleeved, and makes it a bit more difficult to dial in as it relates to the tune. I'm not a tuner, I'm a mechanic, so I left it at that.
However, the key thing to know, is that your PCM, learns and adapts to your driving style, environmental conditions, etc. So over time, it builds up all these learned habits and environmental conditions, and sometimes they have brain farts when presented with something out of the ordinary routine of things. Think of it as leaving your home PC on non-stop for 3 months without a reboot. It's buffer gets full, it slows down, and gets tempermental. Kinda the same thing.
So, if you're stock/stock intake, do a simple idle re-learn by disconnecting the negative side of the battery for a minute or two, then re-install. This will reset the PCM (like a reboot), to it's base learn parameters/tables and then follow as close as you can, the GM driving cycle here http://www.obdii.com/drivecycle.html to get the most out of the re-learn. It should do the the trick. I go 3 - 4 months between having to do this.
01-24-13, 06:47 AM
That seems like a pain in the butt to do every three months. Just IMO.