EJ255 Primary wastegate duty

Hi guys! I am currently learning to tune boost on my 2014 wrx. Everything is stock, turbo and all. Bought it as a project car to learn efi tuning. The issue I’m running into is in the datalogging I’m seeing for primary wastegate duty. The car is hitting desired boost and even overshooting when spooling up in the lower rev ranges. However in the higher rev ranges boost is steadily tapering off. I noticed when logging primary wastegate duty cycle that I’m somewhat close to primary wastegate duty target in the lower rpm ranges, and in the higher rpm ranges wastegate duty tapers off steadily down to about 4% nowhere close to my target. At a face a value what do you guys think? Could it possibly be the wastegate spring is a limiting factor? Again I’m pretty new to this just wanted to pick some brains. Any input would be greatly appreciated thanks guys for the help!!!

Figured it out myself lol it was the intake air temperature compensation tables that were screwing up wastegate duty and target boost at low temperatures because it's cold in CT right now. Didn't even think of it at the time! Zeroed out the tables and my wastegate duty is right on the money now

Generally those need to vary as temp does in order to achieve boost targets with minimal correction, so while it may have been too extreme for your liking, zeroing it out generally won't give ideal results either. Just something to work on as you continue...

i bought a 3 port boost control solenoid and plumbed it up, but am still having issues getting my boost control within an acceptable range in open loop tuning without any PID assistance. I can get it pretty close to within give or take 2 psi of my targets. I think my target boost and wastegate duty cycles are pretty accurate for what i want to achieve, but I am pulling my hair out trying to get the boost dialed in open loop lol. only targeting about 7 psi around 3200 rpm, and 17 by 4400 rpm which the stock turbo can definitely do, even overshooting at times. I just dont seem to be seeing a whole lot of consistency in my boost error graph using megalog viewer hd for the same duty cycles which is what concerns me. I know we are targeting a constantly moving target here, but just feel like I should be getting a little closer and seeing more consistent data. I know theres a lot of possibilities, but any sort of advice at all would be appreciated!! Keep in mind I do live in CT and it is pretty cold here, so my wastegate actual duty is decreased by a certain percentage via the IAT comp tables which I do understand. (put the Intake air temp comp tables back to normal per the factory tune instead of having them zeroed out) Do I just wait till it gets warmer out to try accurately tuning the boost for the targets I want??

Air density is a big factor, so use the baro pressure and IAT comps to help you make things more consistent, but also understand there are other factors involved.

For example load is another factor, so wastegate duty compensation by gear helps normalize the boost behavior across gears. If using COBB that's available, if using something else, take a look for it.

In spool areas, heat in the exhaust system is a big factor. The hotter the exhaust is when you start the pull, the quicker it will spool as more energy is transferred to the turbine wheel. This is not something you'll be able to account for in open loop, but you'll notice it impacts things less towards the top end of the pull.

You're doing the right thing by getting the open loop, feed forward systems dialed in first. Once you've gone as far as you reasonably can with those systems, then use the closed loop system to take care of the rest.