Yes, this can't be stressed enough. Go ahead and tell your tuner that your TB shaft seals are leaking. If he/she tells you that its ok, then your next step is to find another tuner. It's your money, so do what you want. Lemme break it down to you, shotgun style:

mil spec shaft seals - $18-$20
another tune - upwards of $300+

Which would you rather pay?

I know you're anxious. I just had my first tune done this past October, and patience is not a virtue of mine, but I made sure there were no boost leaks and the car was locked/cocked/ready to rock beforehand. We are only trying to save you money/time/headaches in the long run.

 

https://www.evolutionm.net/forums/ev...yone-read.html

Make sure you fix all your boost leaks before you do any type of tuning. It is absolutely pointless to get a tune without fixing them.. as stated above by Chad @ CBRD.

 

Definitely a good investment..even though mine have gone 50k with 30psi no issues.

 

Absolutely 100% correct. Just add in a new and inexpensive TB gasket also

Not to mention that it's not really how much boost you lose. It's more about your MAF calculating the amount of air being drawn in. Your ECU then tells your injectors the amount to spray for that calculated air. If you have a leak after the MAF it will throw off your fuel. Your computer is throwing fuel at air that might not really be there because it leaked out. Hope that's not confusing...lol

This is the easiest way to think about it: 1. MAF sees "X" amount of air. 2. leak and only "A" amount of air gets to the cylinder. 3. Injectors added fuel for "X" amount of air, NOT "A" amount. Since it's a leak, its probably not linear or a constant. That means "A" could always change, throwing your tune out of wack.

Another thing to think about. Depending on how many leaks and how bad they are, it can also cause your turbo to work harder just to make up for the leaks.

I could go on and on...lol

Sorry for the ramblings....

 

there is no way to calculate that...

it will change with temps/pressure, etc...

plain and simple, if you have never replaced them... DO IT, you need them.

EVERY evo we've pressure tested recently has needed them if they werent replaced before!

cheers

cb

 

I have a great before and after dyno chart showing the spool I gained by fixing my shaft seals. I'll post it up when I get home.

 

Here it is. Blue run was with the TB seals leaking. On the red run, I had repaired the seals with WORKS high pressure seals and I also switched from the oem 9.8 housing to the 10.5 housing (which in theory could cause a loss in spool up). This graph isn't back to back...they are separated by about a year...but conditions are very similar. Besides, we aren't comparing power, just spool up. I don't think a relatively drastic increase in spool like that can be called idiopathic, whereas power may change from day to day. I am VERY confident that the increase in spool is due to fixing that leak...

 

Sorry if this isn't the place to ask but does your boost gauge bounce around because of the boost leak in the TB.

 

What mileage do these generally start to go at? Now im concerned about mine.

 

They leak from the factory and only get worse. If getting tuned, replace them. The idea of replacing them may sound intimidating, but it is a pretty simple task, especially when following a how-to.

A boost gauge that is bouncing is most likely a faulty gauge or sending unit.

 

Made 437.7WHP with a pretty big leak from those seals

 

Well that's what I thought it was. So I bought a new boost gauge and it still does it. I did a boost leak test and I was diffentily leaking out of my TB.

 

Im fully picking up a set of the works seals. Done deal.

 

Nice numbers, too bad the seals leaked. Coulda made more!

 

Did you only replace the gauge? The sensors are the more common thing to malfunction on those.