My stock 04 MCS feels a bit lethargic. It has no check engine light and otherwise drives fine. I read a lot of threads on the bypass valve and need a little more help testing mine. The lever springs back while the engine is off, but at idle it is very difficult to push in. Is this normal? When I force it in the idle does not change--should it?

Thanks.

 

Easiest way to check is to simply zip tie it closed and go drive. If the car pulls harder in the upper end, your valve is toast. Just know that in the lower RPM range, it will run like garbage as you are basically full boost all the time.

How old is that one?

If you do replace it, I would go this route.

http://www.detroittuned.com/detroit-tuned-bypass-valve/

I have been running this for several years and love it.

 

I'm not sure how old it is. It looks pretty original. I just got the car 2 months ago and it had no maintenance record (auction car). The carfax is blank. I contacted MINIUSA and they said it only had a recall and a window motor by their records.

 

My guess is that it is probably shot and either way, it is a fairly cheap and easy part to swap. I would probably do it anyway.

 

I'm almost in your exact situation with a new to me 160,000km MCS.
We just did my valve the other day as part of my solution, was only about an hour job.
Detroit Tuned have a great instructions/walkthrough and video available on the product page.
http://www.detroittuned.com/detroit-tuned-bypass-valve/

 

I Change My Bypass Valve For The
Detroit Tuned Bypass Valve.
N' Is Way Better.

Because With The Stock Bypass Valve
Was Alot YoYo.....

Is Like If You Push The Pedal Gas
N' Let Them Go That's The YoYo.

Feel Like That But Not.
Is Because The Spring Is Like Little Loose.

When I Change My I Feel The Difference
Because They Have More Response Quickly N'
They Give Me 1Lb Of Boost Extra.

Here Is My Video When I Changed N' My 2004 MCS

I Hope That Help You.