As the cars pass from new owners through to 2nd and even 3rd hand owners, a lot of information DOES NOT get passed on from one owner to the next. This is something that was not discussed openly as these issues sometimes arised from insufficient fueling capacity of the stock DISI drivetrain and 2007 MS3's suffered this when hard parts were added and no tuning solution was available and the HPFP couldn't keep up. Many owners at the time and still are concerned about resale value and these issues weighed heavily but never discussed.
Recently, there are a number of guys that came to MSpeed looking for a tune... From the get-go, I'm weary of tuning cars and owners that I don't know personally but I was open to meeting the new guys and helping them out. I was also insistent on doing a engine compression test and boost leak test on top of tuning, as part of the diagnostic service. Most passed...some required tightening of hoses...but some also had low engine compression. The cause(s) of low compression is discussed at length on MSF so I am not going to go into details. Mechanically speaking, it's a matter of overheating...and there are many and varied potential causes, one of which is tuning. At MSpeed, my tuning philosophy is tune for smoothness and the power will come naturally. This stems from our group's shared interest in road racing and the need for a smooth and consistent tune is paramount over power...it just so happens a nice track tune translates into pretty awesome street tunes in the right hands.
Beyond this, there's also methanol injection and guys getting tuned for meth and running out. One of the fastest MS3's to have been on Mosport GP track ran his hot tune without meth for 2 days and lost his engine. It's not rocket science, but compared to stock cars where you just change oil and add gas, sometimes our cars might as well be...if not a risky science fair project.
Anyway, a few guys here have recently remedied their engines with low compression. Some of us rebuild...some of us replace parts...some of us don't do anything, and that's fine cuz low compression in most cases, doesn't mean your car will blow up. In fact, all else being equal and unless you did something stupid to cause it, low compression usually just means you ain't making anymore power tomorrow than you did today...bro...
I will talk a bit more on that last point in the next installment of the Mod Path on Med/Big Turbo's. In the meantime, I want to see if the guys who have recently completed a rebuild are willing to share their experience.
Low compression doesn't mean your car is dead. There may be other issues that are causing it to make it worse and it can be fixed. So let's hear it...let's start with @mikey32235. Please share with us how you discovered the issue and how you went about dealing with it.
@MPS