Currently working on tuning my 05 evo 8 with evoscan and I can’t control my boost to save my life. I’m working with my tuner remotely so all the troubleshooting is on my end and I’m looking for advice.
It’s a decent build and the issue related components are:

fic 1220 injectors
aem 340 fuel pump on e85
tial mvs wastegate with 16lb spring
tial q bov with 9lb spring
fp red ss
grimmspeed ebc
omnipower 4bar map
speed density
aem wideband o2 sensor

Tuner currently has it running pretty decent but boost is all over the place. Supposed to be running around 28psi.
1st/2nd gear sometimes jump to 33psi.
3rd gear usually hits around 28psi but sometimes jumps to 31psi.
4th gear usually hits around 24psi.

Tuner says fuel and timing are where they should be but boost has a mind of its own.
I have done 2 boost leak tests and got it to hold 30psi without any leaks with soapy water.
Wastegate opens around 16psi and currently the ebc makes the wastegate flutter open and shut at high boost.
Anyone have any ideas why boost is so erratic? It’s different with each pull.
thanks for any help!

 

Seems to me like you might be having an issue with the EBC itself possibly?
Have you tried just removing the EBC from the system and making sure it holds gate pressure? That is probably where I would start. If it holds gate pressure fine without the EBC, I would look at that. They are pretty cheap for the GM version so its worth having a spare anyways.

The other thing is that this could very easily be a tuning issue with gate duty cycle at given loads. Is the boost consistent run to run when in the same gear? Its a little unclear in your post as you mention its different pull to pull but only posted 1 example of it moving in each gear?

 

Figured out the issue. There is a setting in evoscan that controls boost error correction based on load and it was active so my boost was all over the place. It is now dialed in, thanks for responding!

 

Glad you got it sorted. That makes a lot of sense lol.