I recently had a 2014 stingray Z5, 18000 miles checked out for pre-purchase. The inspector said that performance was flawless, “However, during upshifts at low revs (under 2,000 rpm), traction appeared diminished, resulting in some chattering until the car returned to the previous lower gear. Upshifting above 2,000 rpm, as well as all downshifts, occurred without any problems.”

by the way this is a manual 7 speed.
anybody have any idea what this might be? TIA.

 

I'm no expert but it sounds to me like he was, what we used to call, "lugging the motor". In other words, he was shifting into too high of a gear at too low of a rpm. Under what circumstance would you want to upshift when you are under 2K rpms in your current gear? That rpm range is barely above idle. Again, I'm no expert, but that's my take.

 

It's pure nonsense!

 

thanks for the helpful comment

 

What does, "traction appears diminished" mean?

 

I think it was tires were slipping and gripping, but tires are new.

 

Up shifting under 2000 RPM's and tires loosing traction, I don't think so. Was it the 4 cylinder mode kicking in and out?

 

First, there should be no issue with shifting to a higher gear when rpm is between 1000 and 2000 rpm smooth shifts and engine operation are normal in that rpm range. The LT1 engine has over 300 lb-ft of torque at 1000 rpm and more at higher rpm so there is plenty of torque. Corvettes don't have rubber bands for motors like some cars have. I have a Z06 Vs a Stingray and the OM warns drivers not to operate either engine under 900 rpm. Above 900 rpm you are not lugging the engine and if it bucks or stutters the throttle body more than likely needs cleaning. That isn't a difficult job and can be done by almost any DIYer with the correct screwdrivers, a cloth and some safe solvent (use something that won't damage the surface of the metal). Other causes could be a loose spark plug wire, a bad spark plug or something else.

I am not sure what the inspector meant by traction being diminished on shifts less than 2000 rpm. AFM isn't active unless the Drive Mode is set to ECO. Unlike the A8 cars, it isn't active unless ECO is selected. Even if the Drive Mode selector is set to ECO AFM isn't active in 1st, 2nd or 3rd gears. It is active in 4th, 5th, 6th and 7th gears.

I drive my Z06 around town at less than 1500 rpm all the time and know I can do so with the LT1 as well. The inspector wasn't lugging the vehicle's engine.

Bill

 

None of that comment makes sense but regardless I wonder if it was the skip shift?

 

I don't get the "losing traction" part, especially at the RPM stated (2000). Seems unlikely.