Good day all. I'm new to the forums but not to turbo vehicles. I have a 2014 WRX that is currently stage 2. Running a turbo back Invidia and AEM intake. My car has had an issue with over boosting I have an appointment with Cobb tuning next week but wanted to get opinions. My AP and peak recall both read 27psi when fuel cut hit, I didn't even think the stock turbo was capable of that kind of boost.i have fairly consistently seen as high as 21/22 but never 27. Any ideas would be helpful.
overboost can happen from a few things. the most common are downpipe and wastegate related.
when you add a full turboback exhaust it allows more exhaust flow and will spin your turbine faster without the ECU knowing so the boost will spike as the ECU commpensates for the extra air flow. you have a Cobb AP and you have loaded the proper map (i am assuming) so this is probably not your issue.
now the wastegate is probably your issue.
1) it could be completely broken and does work at all.
2) the actuator arm could be disconnected and its not pushing open the flap.
3) your wastegate duty cycles are somehow completely out of whack and you need a tune. (again, having a cobb ap would suggest this is not your problem as you can load a proper map.
if im to guess from your description, your problem is wastegate related. whatever the reason, its not openeing allowing the extra psi to bleed off. check your actuator arm and make sure its connected, then make sure your wastegate is actually working.
I'll add that in my case my exhaust is so much less restrictive (I went to quad tip without a cat instead of the horrid 1 tip) that I have a boost spike I cannot tune out without losing some boost or overboosting.
It's like this:
1). either let it overboosts and then smooths out to target boost to redline (feels great but regularly hits fuel cuts in higher gears)
2). aggressively tame down wastegate duty cycles AND turbo dynamics to reduce the spike at the expense of not being able to hit target boost later on
This happens on both the stock td-04 and the upgraded vf39.
I've been waiting to install an external waste gate for several months and finally got the parts to do it which should help me. This is likely not your case but if all else fails I wanted to chime in.
Possibly, unless of course one of the things titter mentioned up above is going on.
If you record a log of a pull in third gear and send it over I could take a look at what's happening and possibly give you pointers. But I don't tune with access port so I could only give you some direction.
Was the map you are using designed to work with the exhaust components you put on?
If not it's quite possible that the wastegate duty cycles are too high for your setup (in that the boost control solenoid is bleeding enough pressure from the wastegate's actuator to prevent it from opening when it needs to).
theres a small poosibility it could be your actual boost control solenoid not trigging your wastegate properly. borrow a friends that you know works and go for a drive. see what happens.
adjusting the arm travel could work just remember to go the right way. since your overboosting (flap not opening) you want to extend the arm so the flap is easier to open.
I think the key indicator will be in how the boost spikes. If it's all over the place I would think as titter said above.
On the flip side if it's a sudden spike after spool up than the physical dimension of the wastegate is not able to keep up with the rapid boost change needed to even out the boost to reach the target.
Did this spike occur after a quick gear drop an foot mashing the gas pedal? Try putting it into 3rd an over the course of 5 seconds go WOT. Then be in forth an drop into 3rd an mash the gas pedal.
I notice boost spikes when I do that. It was confirmed to me by my old Tuner as well when I told him what was happening. He said just try not to drop a gear an go WOT immediately. Its different when going through the gear from 1st to 4th to be WOT the entire time.
No it seems to be any WOT situation, I popped in the silencers to increase the back pressure and that has helped. Anyone know where to get a hold of new parts for these vf52's I want to order an exhaust housing so I can do a port without the car being down for too long. I will update once I get my hands on one. Gotta love the Subie nation though very supportive group of vehicle owners!
If you do all the work yourself and have some technical experience and understanding of how your vehicle works, the easiest way would be to use your AP to tune the spike out .
I can give you some reading material but if you tame down the wastegate duty cycles during spool up you can probably tune that out.
Lol that is probably true but maps scare the crap outa me. I've seen more than one fool blow his motor over a case of pride. If you don't mind schooling me a bit I'll give it a shot....and then buy a second turbo lol!
You want to have a 3d gear pull that captures rpm, engine load, target boost, manifold relative pressure (corrected), Fine Learning and Feedback Knock.
If you want to try, let me know when you can do this.
Problem fixed! Installed an avo top mount and silencers. Been running the crap outa the Subie and she is loving the new setup. I guess it needed a little more restriction on the exhaust and less on the intake side, just flows better. Peaking and able to hold 19psi +/- . Feels a lot quicker also. Thanks for the help everyone!!!
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