I am new to this site. I have looked at most of the posts on here about bad gas or dirty fuel filters, But can anyone who has had bad gas or dirty filter tell me how their MCS was acting?! I only put premium in my car, however I think it was bad. My car will idle fine, start fine, and drive. However when driving it loses power, then gets it back (it jerks and jerks). It is ruff idling some to but not much...

 

Could be you just got a huge dose of the winter conditioned gas in there from last fill up, and the ECU has not finished making it's adjustments.

If you don't want to wait the usual two tank loads before it smooths out, you could always reset the ECU manually.

 

Do you hear any audible knocking or pinging too?

Assuming you have an R56 (07+), your fuel pump is most likely on its way out. Very common issue.

 

It gets bad and dies when you are driven down the road and I have to restart it!!! Not sure it is safe to drive...

 

I have a 2004 mini s 6 speed manual (not sure what the R5S is). I do not hear anything!!! I have been reading on the site and have found how to locate the fuel filter ... ... I may even be able to change the fuel filter with the post on here it is great I am still new to the mini world I am loving this site!!!