Hi All

driving home yesterday I lost power in my 2007 R52 (gen 1 engine) MCS convertible.

Car the EML + DCS + service engine lights lights were on (battery light came on the first time) car was relegated to 30mph but got me somewhere safe to pull over. Temp, Oil pressure, and oil temperature were normal on the gauges. When I popped the hood there looked to be a little oil on the upper part of the engine compartment behind the valve cover. I made sure the oil cap was tight. When I restarted the car the service engine light stayed on other were not lit and the car drove and felt normal. after two starts the SES was off and the fluid that I noticed in the car had evaporated making me think it was not actually oil perhaps coolant.

Anyway the Limp mode returned on the way home and as the distance was short I restarted and took her home. Coolant levels were normal and coolant looked ok. Oil was a wee low but also did not look chalky and no tail pipe smoke. At a bit of a loss as to what this could be?

head gasket or valve cover gasket. I think it must be a leak because my belt started squealing (not badly but enough to make me think something was getting on it)

If anyone has experienced this limp mode and a list of possible limp mode causes I would be most grateful in my question for repair

 

Go to your local auto parts store and have them read codes. I just threw a code that was a throttle position sensor bad but when they read the code it also said possible low voltage. I charged my battery, which was at 85%, and my limp mode went away and has not come back.

 

Look at the crank damper on the passenger side (us) of the motor...
When they fail, they slip and then grab a bit...then heat up...slip..basicly the rubber between the metal inner and outer edges(it is a dampener pulley) fails...
When it is slipping you have no sc, no water pump, no alternator, and no ac...so might not be your case, but the squeel, limp mode, makes me me look...also has an odd smell from the rubber...more of a popcorn smell than burning rubber...
If that seems OK...try to get the codes read....
Just be cautious...
Codes tell you what sensors are reading that is out of limit...it COULD be a sensor, or simply the sensor us reporting something upstream has failed...
Many things cause "limp" mode...it is just the computer saying "this data coming in makes nonsense, I give up".

 

Thank you all come to think of it there was a funny smell that I could not place. Battery is about 5 years old as well. Dropping it off at my shop tomorrow as I do not have the time currently to work on this will forward the data when I get it and will update you on your well thought out hypotheses

 

I've had this a few times now, always under hard acceleration. I don't think I was WOT but maybe, I'm pretty sure I didn't redline (eyes were on the road). The car limps until I restart, the after two more restarts the Service Engine Soon light goes off and all seems normal. The last time, I put it in neutral and restarted while still rolling forward in my lane. Is it bad that I've learned how to resolve this without pulling off the road? LOL!

 

It was the pulley as you suggested Zippy thank you!!!


Edit as you said codes were Airflow codes which were tossed because the supercharger was not functioning correctly pushing air into a thankfully functioning MAF

 

Glad to hear you found it!!