[GtiGyver]

Hello everyone,
I have searched for this and found no answers.

Basically the problem I have is this:
At the track of course, I'd be at the top of third, hit the rev limiter, shift into 4th (having let off the gas during the shift), go back to WOT and all I get is an odd sound from under the hood, like a faint hum/buzz, and no power what-so-ever. In fact, the car slows down more than if I had the throttle closed.
If I wait even half a second and get back on the gas, the power is back. All of it.

No CEL, no codes.

The car does have a JB4 and an aftermarket midpipe, no other related mods.

I'll admit, I do not have any logs of this unfortunately as it does not happen every time, nor is it easy to legally get to the top of 3rd on public roads in order to try to reproduce.

Any ideas?

[GeorgiaTech335coupe]

Post shift bog. Pretty common in this car. Also, the dme will close throttle in anticipation of hitting the rev limiter. This will discharge all boost and more than likely cause a post shift bog. Logs would help to see exactly what is going on.

[JMARS]

Check for a humming bird under the hood... I heard they suck up power like no other. Good luck those suckers are QUICK! ;-)

[marcvtec]

Shift bog issue, happens to my car at the track almost every time.
I've heard bullshit stuff like bog fix from bms and procede, never fixed my problem from either.
I've heard shift slower and at less rpm like 6000, this sometimes worked for me, but when racing it is kinda hard to shift slow.
Now I will try with Cobb as soon as my turbos arrive to see what we can do with it.
I know your pain, I hate that one second delay.

[themyst]

piggyback + 6mt you will bog and bog badly. flash tunes seem to resolve the issue.

[roadkillrob]

The power drops off pretty significantly before redline and there really is no reason to shift at redline as the car is faster shifted earlier. Stock and most tunes drop off significantly at 6700 rpm and some aggressive tunes taper much earlier and are hardly worth revving past 6500 or even 6000 - no reason to be bouncing it off the limiter, it will actually slow you down unless you just need to use it more like it is over rev because you don't have enough room to shift.

[n54door]

Try to shift a tad earlier, but still quick, and if you can manage, don't fully let off the throttle (but dont floor it either), while shifting to the next gear. It's sort of like flat foot shifting, but without holding the gas pedal all the way to the floor, just halfway maybe. This will allow the boost to hold for that extra second.

Works for me!

[GtiGyver]

Thanks guys,
makes sense. I agree, on these cars it is definitely useless to go deep into the revs past 6500rpm, but I just was unable to hear my car, I could only hear the mustang next to me lol.
I'll maybe try to play with the boost settings on the JB4 to cut boost significantly at the top end so I can get a 'feel' for the shift point.

Cheers!!

[Mike@N54Tuning.com]

You can also bog running flash only without much effort. The only real fix is no lift shifting. The JB4 supports NLS but you normally also need the back end flash loaded for fueling to work out properly with it in place.

Mike

[themyst]

bogging killed me when I had a 6MT... I dont know whats worse, flatlining on 6AT or bogging on 6MT.

[Mike@N54Tuning.com]

Originally Posted by themyst

bogging killed me when I had a 6MT... I dont know whats worse, flatlining on 6AT or bogging on 6MT.

How is this for power after the shift. This is a 3-4-5 dynojet run using the JB4 no lift shifting and RB turbos.

Mike