Suspended NASCAR Sprint Cup driver A.J. Allmendinger has released some more information about his sudden failed drug test and suspension, but is still leaving some questions unanswered.

FOX News Radio's Lisa Brady reports:

Without admitting any guilt, A.J. Allmendinger says a stimulant is what turned up in his drug test.  A statement released by his business manager doesn't specify which stimulant, but says Allmendinger has never knowingly taken any prohibited substance, and that the driver's medicines and supplements are being collected to test for any possible over-the-counter link.

Allmendinger's also requesting that his alternate urine sample be tested.  The 30-year-old first-year Penske driver was suspended last Saturday, just hours before a race.  Already replaced for this weekend, too.

Lisa Brady, FOX News Radio.