Hi. I have a 05 MCS that has around 85K miles. At first it seemed as though I started to feel the real power around 3k rpm and now it seems like it is later around 4k or so (supercharger kicking in later than before, does that make sense?). Any ideas?

 

check the bypass / blow off valve and inter cooler boots. The SC may need service but if it's not making noise look at the other stuff 1st.

 

Thanks for the quick reply. When you say check the intercooler bolts, does that mean see if they are loose? I thought I saw a tread on the bypass valve, I will look for it.

Thanks
John

 

Towards the end of this thread they talk about the bypass valve and have pictures of where to look.

https://www.northamericanmotoring.co...o-results.html

 

Boots, not bolts. The rubber connectors between the intercooler and the SC horn and intake. They don't usually loosen spontaneously, but they're easy to check.

 

it's not the bolts it's the rubber of the boots. Some have leaked when they dry out from none use. We see this with MINI's here in Chicago that are stored for the winter.

 

Hi All,

I replaced the BPV with a new one from DT. The old one seemed to be ok, just not as strong as the DT (spring). Now that I have it all back together, I'm getting the Unmettered airflow error (on EML) #1498, plus while the engine is idling, it goes up and down about 500 rpm, like someone is pushing the pedal and letting of, over and over. Anyone ever seen that?

Thanks
John

 

sounds like a vacuum leak -- recheck all your hose connections and make sure everything is hooked up right

 

I will thanks! The vacuum line to the TB makes sense, it must be faulty. Also when you let of the gas comming to a stop, it floats for a bit then let's off. How does the vacuum for the BPV work? There was just a line from it to itself

 

Stupid question.....have you checked you belt lately? Might be slipping a bit at higher rpm....you should be on your second or third belt for an '05 with your mileage ...the most recent problem does sound like a vacuum leak...have you reset you computer since the new valve install?

 

Your symptoms (initially) sounded a lot like what I'm seeing - not yo-yo- but the power lag I talk about later in the thread, that was evident after the yo-yo was fixed - power feeling like it "comes on" at about 4000 RPM. Some other folks have reported the same symptom, with different mods, tunes, etc. Very perplexing. Mine went away for a little while - and now it's back.

https://www.northamericanmotoring.co...h-a-twist.html

 

Thanks all. I can't seem to find any issues with the vacuum, but no real way to test other than replacing the part going to the TB (at least I'm assuming that is the only one that would be causing the problem). I've got the TB out now and just going to put it all back together, reseat vacuum lines, etc. and see if it works any better.

I reset the computer after I put the BPV in.

 

Put it all back together and reset the computer. No problems as of yet. Not sure what the problem was, but must have been a vacuum issue.

I will probably get a new belt as well.

Thanks everyone!