I just completed my first mod to my 06 Evo. It is a Zeitronics Zt2 datalogger. So sweet, I go and run it hard for a while, all gears, all rpms. Hit the peak button and the highest recorded MAP is 16.6? I teed the zeitronic map sensor off the bov vacuum line right at the intake manifold. All connections soldered; no hack.
The car is bone stock and has never ever been modified. I do run 91 octane and am at 5k feet. It was 65 degrees today. Could these circumstances pulled back boost? The car runs perfectly otherwise. It feels strong but I've never driven another evo. I'm concerned because I'm about to start modifying the car heavily but want it running perfectly before I start.

 

I'd get a manual boost gauge and verify what your data logger is telling you.

My two guesses are:

1. Boost leaks - check for leaks. I've heard of people having major boost leaks on stock cars.

2. The data logger may only have a 2-bar pressure sensor (vacuum and ~15.7 lbs) which may be reading 16.6 if it's not exactly a 2-bar sensor.
- Edit: Just looked at your datalogger, and it shouldn't be this problem as the smallest MAP was good to 50psi.

 

I have the stock mr gauge, it shows boost to 1.2 or 1.3 of whatever the scale is. How does this correspond to psi? I havn't done any checking for boost leaks, but from what I've read elsewhere they are either sudden drops or it takes a long time to build boost; neither of which this car exhibits.

 

i think the stock are in bar so with that 1.25 ~ 18psi

 

And the accuracy of that gauge is also going to be very questionable. I would guess that your datalogger is accurate.

Boost leaks don't necessarily behave as you've stated in your post. A boost leak will just be a clamp or hose or whatever that isn't sealed 100%. The clamps could be under tightened, over tightened (mine were), or you could have holes somewhere. Depending on the size of the hole or nature of the leak, you will either always be loosing or as you said will see a drop off at higher boosts... but it won't be a sudden drop unless something pops off.

As for taking a while to build boost, I'm not saying it isn't possible, but I don't see how a boost leak could keep you from building boost unless its a horrible leak, in which case your car will run like crap, or you won't build any boost.

Do the boost leak test. It will only take a little while to check and you could find some free power.

 

conversion is 1 Bar ~ 14.5psi

so:

1.2 Bar = 17.4 psi
1.3 Bar = 18.85 psi

 

All right, leak test it is. I'll report back and thanks for the input.

 

I just pumped 30 psi into it. Sure enough there is a leak, it's the throttle body accel pivot rod. It's obvious, but it still takes 30 seconds to purge the system of pressure. This is not helping but I can't believe enough volume of air is escaping that the turbo can't keep up with it.

 

16.6 is around 1.1 bar

 

I don't think the stock gauge reads BAR. It says kg/cm2

 

What next? I replace the tb seals with mil spec seals. Put it all back together and now I have 17 tapering to 14. wtf hardly the improvement I was looking for. Again, car idles great, runs well at all rpms, has 10k miles, all stock only mod is the datalogger.

 

Throw it on a dyno. There is a good chance that the boost logger is off by a bit. A dyno will tell you if you are where you should be or are running crap.

 

You did install them properly right i put mine in backward at first and still was doing the same thing and still had the boost leak at the same place even worse do another boost leak test make sure the tb is not leaking anymore

 

The seal should be installed with the lip facing out, just like the stock seal right? I have to drive 1500 miles this weekend. A new leak test might have to wait.

 

Yeah that would be the correct way they go it was pita wasnt it