Redline=defuel?

[kanddr]

I was merging on a highway the other day and had to floor it in first gear to get around a car. I was looking in my mirror and didnt pay attention how close I was getting to redline until I suddenly lost power. I shifted to second and it was fine.
My question is, shouldnt it just bounced off redline instead of defueling? Is this normal?

[Goober]

No when you redline it shuts you down until you lower the RPMs.

[Green Machine]

Lol I did something similar yesterday and was like wtf at first

Sent from the road.

[Biscuitpie]

Yeah it's a little different than what you're probably used to. It honestly feels worse than just bouncing on the limiter.

[S3XPanther]

And here I was thinking I was making perfect redline shifts lmao. Damn, I really thought it was supposed to bounce off the limiter. Guess you learn something new everyday.

[not]

Yeah, go figure that if GM is giving a 5/100k powertrain warranty, all the idiot proofing plus will be in the works. Just downshifting with the paddles in sport mode and I have gotten a few "Shift Denied". Somehow, even alone in the car, I feel embarrassed....

[RubyCamaro]

The worst one was one time leaving a car show I had it in sport mode & decided to get on it a bit, but apparently when I hit a bump in the parking lot pulling out it bumped into "M" without me realizing it so I hit the rev limiter so loudly, my husband heard it in his Camaro in front of me with his windows up.

[fbodfather]

Originally Posted by kanddr

I was merging on a highway the other day and had to floor it in first gear to get around a car. I was looking in my mirror and didnt pay attention how close I was getting to redline until I suddenly lost power. I shifted to second and it was fine.
My question is, shouldnt it just bounced off redline instead of defueling? Is this normal?

bouncing off the rev-limiter with the car in neutral is one thing - doing it in gear (esp. manual trans) could damage the driveline by excessive force (...think about it...) that's why it will 'defuel' (interesting word, by the way..) for a moment until the revs drop below a certain level.......

[Biscuitpie]

Originally Posted by fbodfather

bouncing off the rev-limiter with the car in neutral is one thing - doing it in gear (esp. manual trans) could damage the driveline by excessive force (...think about it...) that's why it will 'defuel' (interesting word, by the way..) for a moment until the revs drop below a certain level.......

I've heard the opposite, that it's much worse to rev it unloaded.

[Trentin24]

Originally Posted by Biscuitpie

I've heard the opposite, that it's much worse to rev it unloaded.

Like dry-firing a bow

[OK2DRUL]

Running up to the redline without a load on the engine will destroy it faster than with the car in gear. The defueling system is similar to other GM products. It's like hitting the speed govenor in a truck, it turns the fuel off to the engine until the speed returns to what the computer deems "safe" and then it'll pick up speed again if you were to hold your foot to the floor.

[not]

L99 automatics will only go to 4,000rpm in park max. That is reason enough for a muffler delete, ha.

[kanddr]

Thanks for the input guys. I guess the only solution is to shift before it cuts off the fuel next time.

[christianchevell]

ideally shifting should be done in the power band which is the optimal amount of power the engine is creating before it begins to decline in power.......our power band for our engine makes its most power in the upper 4000 rpm range. I you shift making the most power the engine can make then go to that power again you are rowing through the gears to a better gear moving faster as fast as possible, going slightly over the power band makes it easier to hit the same amount of power band more instantly when going to the other gear if you let off the accelerator some as many do with shifting. This is why automatics are more a constant for shifting at the same rpm for bracket racing and can be built so well for drag racing as a trans can be programmed to make the same shifts time and time again if built that way.

Unfortunately the trans in the l99 has a weak shift change for the "sport mode", especially weak compared to a good old shift kitted th350 or 400 which would literally push you back in the seat as it hit every gear and you could feel them hit. Thus they have the pick your own shift point for the "paddle shift" which could be a real pain doing a corner..... Let alone they stuck the automatic with the AFM.

How long a car should stay in each gear in the power band and which gear accelerates the best at any given speed is dependent on how the automatic or manual transmission is made along with the cars weight and given traction and the driver especially if they are shifting the car, ( not a shift controlled by the auto transmission at its preset shift point). Seat of the pants is the way I always drove my old chevys and being able to tell when you hit a gear too soon or too late are hard to tell if your close to as fast every time...... But bouncing off the rev limiter yes .....I have done it when in a hurry a couple times as going fast in traffic with distractions and annoying motorists and just to see how it performs and believe as with any other car to shift in the peak area of the power band is the best to go the next gear to be the fastest as possible. If one gear has a performance advantage to make our manual trans make a little more time up to keep it in that gear longer is some thing I have not heard, and sensible lower than peak rpm of course has got to be easier on the transmission. And I was disappointed in the auto trans ss I owned for year especially compared to the manual I own now, and I understand a tune can make a hell of a difference, unfortunately it can also void a warranty just as fast.