snaps2k

Today as I parked and turned the ignition key to 'off' the car continued to run irregularly with a grinding noise and light white smoke from underneath the throttle cable/headers area. Turning the key back to 'on' stopped the grinding and the car would idle and rev normally with no issue, but any attempt to turn the car off like normal would result in more of the grinding and burning/ozone smell.

After purposely stalling the engine to get it to stop running, the ignition button now clicks but the car no longer starts. All electronics still seem to work in the cabin and dash lights, and there is no CEL on the dash.

From what I figure, I experienced Run-on or dieseling (http://mgaguru.com/mgtech/engine/ro101.htm), but I'm not sure why that would have affected the starter motor. The last maintenance I performed was cleaning the PCV valve, IACV and performing a map whack, but that was over a month ago and the car has been driven daily with no issues until now. This did happen on a new tank of Arco 91 premium gas, so perhaps they had quality issues with that batch of gas?

I've ordered a new starter motor for now, but is there anything else it could possibly be?

EDIT:
I successfully replaced the starter motor and that seems to have fixed the problem! The old starter definitely smelled 'burnt' and the car started and ran with no further issues. I'm hoping it was just the Bendix spring failing as windhund mentioned, causing the starter to grind itself to death. Thanks everyone!

s2000Junky

Well this is weird. First ive heard of such a problem with a s2k. The starter may be fried now, but that would not be the cause of the engine run on. Also, typical dieseling is really a thing of the past with new gen cars such as the s2k. The main causes of dieseling was caused from poor carburation and tune and or leaded fuel leaving deposits in the cylinders, which then could heat up enough to continue to ignite left over fuel even though spark from ignition system was cut, hence the term (dieseling)so I have no idea what would cause a seemingly similar situation in your case. I doubt it was "dieseling" per say in the firm definition, but maybe "run on" would be more accurate, but i wasn't there to hear it. I'm just not sure exactly what would cause that, unless something in your ignition system has gone wonky. Get anything wet? Id probably start checking some fuses, not that I think a blown fuse would cause this problem, but it might better direct you to a source or group of sources. Could be a strait up ecu issue.

windhund116

Sounds like the Bendix spring mechanism in your starter and/or starter solenoid maybe sticking or broken. Pull the starter and solenoid ---> inspect springs and action.

snaps2k

Thanks for the response, guys. I was able to push-start the car to drive it home with no other issues but the ignition still isn't working.
I'll definitely try checking the starter and solenoid today and report back.