2001 A4, at Laguna Seca Monday, my 8th trip to that track.

On my first session I noticed what seemed to be the engine bogging when coming out of turns, particularly noticeable after 2-3 shifts; 1- 2 seconds later acceleration resumed as normal. It felt like brake(s) were being lightly applied or maybe timing being significantly retarded.

Tracking since 2011, this symptom has not appeared before. Always tracked with the active handling system ON in the past.

For the second session I put the active handling system into COMPETITIVE DRIVING mode and the bogging disappeared.

Reading about the system, brakes cannot be applied unless there is pressure from the master cylinder, so that seems unlikely.

No PCM or TCS codes at the end of the day.

It also appears to me that in Competitive driving, you cannot read GAUGES on the DIC because the DIC displays COMPETITIVE DRIVING. If you clear the competitive driving annotation so you can, for instance, read oil temperature, the system goes back to active handling on. Is that right?

Any thoughts or insights?

 

Thanks, I will check codes from time to time before shutdown and report back when/ if I find the problem.

 

It seems you're confusing traction control and active handling and/or using the terms interchangeably.

The "symptom" you're describing is the action of traction control, not active handling. Traction control is what cuts engine power through timing retard/throttle modulation. Active handling just keeps you going where you're pointed using the service brakes only (yes, without pressure from the master cylinder, not sure where you read that). In competitive driving mode, traction control is turned off but active handling is still on. That means you can spin the tires without engine power being cut.

It is possible that you simply triggered traction control for the first time that day, so you thought it was a problem. Maybe the weather was cooler or your tires are a little worn out compared to usual, either way, you lost rear wheel traction and the car reacted by cutting power. This is normal with traction control on.

By the way, hitting the reset button to remove the competitive driving message on your DIC does not change what mode you're in. You will still be in that mode until you either turn traction control back on (or off) or cycle the ignition.

Typically, the symptoms you will have from a failing steering wheel position sensor is unwanted active handling activation. This can happen in either competitive driving or regular modes. The symptom would ultimately be pulling to one side or another for a short time without steering input combined with the message "Active Handling" on the DIC. This does not seem to be your issue.


This thread sheds some extra light on what you're describing and uses all the correct terminology:
https://www.corvetteforum.com/forums...trol-work.html

 

Not sure how much power you're pushing, but my stock Z06 will activate T/C HARD on aggressive 2-3 shifts. Feels like intense power cut.

 

Thanks for that information from both vipmiller803 and ArtClassShank.

I will save the posts/ links and have read it all and will read again. I am now thinking that there is nothing wrong with the car but will monitor codes as noted previously.

Very nice to know that I can clear the COMPETITIVE DRIVING message and monitor oil and transmission fluid temperatures while staying in that mode.

The engine is stock but I changed to 3.73 rear drive ratio with Wavetrac differential and I am thinking that, and the post from ArtClassShank is the reason there may be some wheelspin on the 2-3 shift at times, particularly when still pulling some G out of a turn.

I was also surprised to leave some tire smoke and two black stripes leaving the hot pits on Monday for the first time in COMPETITIVE DRIVING mode.

My avatar is turn 5 on Monday in COMPETITIVE DRIVING mode for the first time-

 

Yeah,,, I was going to tell you to glance down at the DIC when you feel the car do weird stuff and you should see ACTIVE HANDLING "ACTIVE" or TRACTION CONTROL "ACTIVE" if they really did intervene during the event. The message only stays there for a very short period of time.