Technical questions for a 2002 Z06, ~1100miles:

[First: Dealer found no problems and no codes (I have access to an AutoTap, which I'll try later)]

1. Vibration felt through clutch pedal and shifter handle. Resonant harmonics at 1600, 3200 (and probably 4800)

RPM's while in neutral. The car also vibrates under these conditions (not major, but noticeable). Local

Corvette expert states the clutch is out of balance. Dealer called GM's TAN; condition is "normal". I'll try to get access to an NVH Vibrometer. Will try another dealer. Question: Is this normal?

2. Engine hesitates after WOT in 1st when shifting to 2nd (shifting at 6000). Feels like fuel starvation. Is this normal?

3. Local Corvette expert states engine is louder than any of the others they have worked on. Bad lifter(s)?

Noisey injector(s)? Dealer states "Normal".

4. During decel (mostly while cold, sometimes while hot), afterfire is heard. This is felt through the seats, and appears to be coming from the right side only. This sound/effect can be described as a loud thump in the

exhaust. This is not to be confused with the normal "pop pop pop" sound of all LS1/LS6's. Local Corvette expert states this is not normal. Where is the extra fuel/air coming from to allow this to occur?

5. A very high pitched whine can be heard from the engine. Sounds like an air leak. The sound can be described as very similar to a supercharger whine (the car is stock), or even electronic noise while the radio is on (My first thought, until I turned off the radio and could still hear the sound (with the hood open while listening to the engine)). Local Corvette expert stated that most C5's they see have aftermarket air intakes, and suspects the sound may be coming from the stock air box. Is this normal for a stock vehicle?


Minor build quality issues (brought to the dealer to have fixed; no items fixed after 2 days in the shop, 26 miles put on the car, returned with RESERVE FUEL <empty>):

1. Exhaust jingle (solution: X-pipe?).
2. Driver's side window wind noise (common problem?). Window was adjusted by dealer. No effect (no longer seats weather stripping correctly; will take to another dealer). Solution?
3. Rattle in passenger side door (no big deal; nonetheless they did not fix it). Ideas how to fix?

Good News:

Engine was broken in with zero high RPM light load driving (500 miles). Now at ~1100 miles, driven normally, still no oil use. Will change oil at around 1500-2000 miles.

Thanks for any tips/help.

SportsCars

 

A little research turned up:

#01-08-58-001 Windnoise Around B-Pillar (Add Sealer) - (01/29/2001)

#01-08-64-009 Door Rattle with Moderate to High Audio System Volume (Insulate Door Components) - (06/11/2001)

1-2 shift hesitation solution?

#02-06-04-001 Lack of Power Following a Wide Open Throttle 4-2 or 3-2 Downshift and Subsequent 2-3 Upshift (Reprogram PCM) - (01/08/2002)

Is this for an A4, or does it also apply to the M12?

#01-07-30-023B Harsh 1-2 Upshift, SES, MIL, or CEL Illuminated, DTC P1870 Set (Replace Valve Body) - (03/22/2002)

High-pitched noise, 1-2 hesitation, afterfiring?

#02-06-01-021 Whistle Noise From Intake Manifold/Throttle Body (Replace Intake Manifold) - (05/22/2002)

#99-06-04-030 Hesitation, Sag, Stumble and/or Backfire on Acceleration (Reprogram PCM) - (08/16/1999)

Again, is vibration through clutch pedal+shifter normal? Please post if your Z06 does NOT have any vibration through the clutch pedal/shifter.

SportsCars

 

Mine is an 02 with 2600 miles and has no vibration through the shifter/clutch pedal.

 

Turning your traction control off will cure number 2.

 

Thanks for the info :-). I went to another dealer today and showed the salesman my car (vibrating at 3200 RPMs). He was kind enough to try the same test with a brand new Z06 on their lot. No vibration at all. :cool: I did hear the whistle noise, though. :confused:

These are all really minor issues. This is a great car. :flag

SportsCars

 

Thanks for the tip- I tried the car in Competition Mode (CM), straight line; no difference. It was my understanding that CM allows wheel spin and only just provides (Active Handling (AH)) yaw control? :confused:

I will try AH Off Mode...

SportsCars

 

950 miles,no vibration.

 

The tach is a little behind the actual RPM. Maybe you are hitting the rev limiter???

 

GasBoy- thanks for the data point.

Shaky-

That thought has crossed my mind. Perhaps the shifts were right on the edge of the rev limiter, such that it wasn't audible, but still active for a brief moment when going into second (granny shifts). Engine inertia carries the R's into the rev limit range after throttle is lifted; no rev limiter sound... That's a very good possibility. I'll try different shift points. Thanks for the tach-lag tip.

SportsCars