Subaru WRX Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
161 Posts
Discussion Starter · #1 ·
So since the beginning of my journey with this car, I've noticed what I would call "turbo surge" when at high speeds. Say I'm going 80 (legal in MT) and I want to pass a trucker before the exit, I'll step on it. When i do this, the car seems to surge and you can hear the turbo/intake noise pick up, and then drop. repeatedly. If I remember right I could even feel when this would happen, as the car would somewhat surge in acceleration. It's gotten to be hardly noticeable now, but I remember back then I could feel it. I can only feel this in 4th or 5th, so I'm trying to figure it out. I don't have a boost gauge(its in transit now) so I'm having a hard time telling what's going on. I somewhat think it's the wastegate letting too much by intermittently, but then I've also wondered about the bpv. Maybe that's letting air go by? The car has a nameless catless uppipe & downpipe. The only other thing I can think of is the hacked snorkus mod, and some aftermarket ~red~ intercooler hoses. Has anyone heard of something like this before?
 

·
Master Baiter
Joined
·
12,649 Posts
Are you downshifting before "stepping on it"?
 

·
Registered
Joined
·
427 Posts
my bugeye does that sometimes too. I've probably got different mods than you though.

I haven't really looked at it cause it only happened a couple of times when I had to safely swing around a tractor trailer to catch an exit.

I think it's something to do with the boost control system. I've got a self-made tune(it sucks, needs work) GM boost solenoid, PNPed turbo, most of the headers PNPed, GS topmount and 3in turbo back. I'm planning on putting a manual boost controller in the mix so I'll have a hybrid boost control setup. That should make it easier to tune out the boost surge/ oscillation.

I'm not 100% sure though about what is causing it. My bugeye has been doing it for a few years and it ain't blowed up yet.
 

·
Registered
Joined
·
161 Posts
Discussion Starter · #5 ·
I assumed it must come from the boost control system as well. I mean that's pretty much what seems like is happening. Do you have a boost gauge? I'm unable to monitor mine when this happens because my gauge hasn't arrived yet. Also, could this problem be because we don't have correct tunes? I have no idea what my car is running and if your self made tune is sucky, that could be our issue.
 

·
Premium Member
Joined
·
12,314 Posts
His is what I would consider an advanced setup that he is developing still - good info but not apples to oranges.

OP - A map is not critical for bugeyes (only) with no cats (and stock boost control) as long as the intake is stock. I don't recall the snorkus delete changing that but can't confirm 100% without searching. But yes you want one, and it is better in every way, and may help.

I think it is about finding a leak, checking for the restrictor pills etc.. Check everything after the turbo - gaskets under the intercooler, clamps & hoses to and from the intercooler BPV gaskets. How To Boostleak Test a Subaru

If your BPV is dumping you might be able to hear it.
 

·
Registered
Joined
·
427 Posts
I do have a boost gauge and logged it once or twice. Couldn't nail the problem down though, yeh still working on the "advanced setup".

The boost gauge would bounce up and down. It would go to peak boost then drop about 5 psi and bounce right back and would repeat until I got off the throttle.

I have had a few smaller boost leaks but I fixed those and the problem remained.

I've been away from home and my car for a good while though, almost 5 months, yeh work sucks sometimes.

I know it is kinda apples to oranges because I have more parts for problems to show up.
The biggest thing I wanted to let OP know was my car hasn't blown up yet.

Checking for leaks (both hot and cold side of turbo), doing some logging, and re-evaluate my tune is my planned method of attack. I am going to throw a manual boost controller at it at some point to. Matty said I had to or I was a punk... something like that anyway.
 

·
Registered
Joined
·
161 Posts
Discussion Starter · #10 · (Edited)
Update

Just got the gauge installed and took it for a short drive. Haven't got around to leak testing yet. The drive made me freak out a little. I guess I don't know what normal numbers are, so I'll say mine and hopefully someone can tell me these are okay.

Idle: -20
Driving(1000-3000 rpm): bounces around but eventually settles at around -19
Harder throttle(4000 rpm): peak boost hit was 17 but backs off to around 10. 10 is pretty constant for accelerating on the interstate.

My concerns:
20 in vacuum seems really low to me, but I could be wrong...
so, for peak boost. I did a little pull to monitor the gauge as I felt the surging.. I didn't notice it hit 17 until I did "peak recall" but after it hit 17 it bounced down to about 9. Back up to 13ish, down to 10. Somewhat leveled out around 10-12 but I backed off the throttle soon after. Doesn't 17 seem pretty high? I'm sure the previous owner messed with the ECU because 17 seems high.
Also one thing to note, I'm pretty sure through gear 1 and 2 the gauge never passed 0, so it was in vacuum the whole time. Seems weird to me.

Now along with the check engine light coming on during my ride home from work(before gauge was fully installed), I've got a lot to think and worry about.. hopefully you guys can shed some light on what's going on with the boost issues. I still agree with the leaks but I think it's weird it can still make its way up to 17.
Thanks guys.
 

·
Registered
Joined
·
161 Posts
Discussion Starter · #11 ·
After a couple more days and some interstate driving, I've seen a couple things. First off, I stepped on the gas the other day and hit something like 18 to 19 psi. I've noticed it will bounce back down and hold at 10 while accelerating. I still haven't gotten around to boost leak testing because it's hot as balls where I live and it seems like a long process to make a boost leak tester. I'm going to look into getting the parts tonight.
 

·
Registered
Joined
·
161 Posts
Discussion Starter · #12 ·
Found most of the problem! My purge valve + surrounding hoses were super hard, creating little to no seal. I hooked it up in a JDM fashion, deleting the purge valve and capping off some nipples. I started it up soon after and saw a huge difference. The boost gauge was much more responsive and I could actually see boost spikes. I notices as the hood was open after started it up that there was a high pitched squealing... now just have to find that leak... Boost now will hold around 12. STILL haven't made a boost leak tester. Hopefully I'll have more time to make one now that I'm headed off to college, but we'll see. I really shouldn't be procrastinating on that
 

·
Registered
Joined
·
161 Posts
Discussion Starter · #13 · (Edited)
Well, about a year later I made a boost leak tester. I threw my tester in turbo inlet, turned the valve, expecting to hear a hissing sound, but instead heard rushing air. I couldn't hold 1 psi. Check the IC hoses, and find that one of them doesn't even have a clamp on it.. really happy about that one. I tracked down a few leaks, I think I made things a lot better. I'm pretty sure I have a few more to find though.. Also, I was trying to follow
DIY Boost Leak Tester <------ that link. It says to cap off a lot of ****, but I was so excited to use my shiny new tester that I didn't follow the instructions.. I ended up sending a LOT of air through my oil. If I had the cap off, I couldn't hold any pressure. I'm pretty sure this is because I wasn't following instructions, but I'll try and do that next weekend...

BTW here it is



Please
Excuse
My
Dirty
Ass
Steering fluid reservoir

 

·
Premium Member
Joined
·
12,314 Posts
Good to hear it worked out.
 

·
Registered
Joined
·
161 Posts
Discussion Starter · #15 ·
Well... I've put a hose clamp or ziptie on nearly every rubber hose I've seen. I used a lot of zipties. Truly, I don't know how my wastegate is supposed to work. Is it normal to have spiking to 18 to have it drop down? I just took off the gauge last night so I could install more, but it seemed like it would settle around the stock boost setting, which was good. Maybe I have a sticky wastegate? It just seems like I still have this surging, just later than before. I can get above 14, but it will drop back down to 14.. It just bugs me because it is easy to feel while driving. I cant remember correctly, but is the solenoid controlled electronically? I'm wondering if the previous owner messed with it. I'll recheck all BVP lines again, but I just can't seem to get it.

I'm really happy that it holds at 10 psi, cause before it would either surge up at that point or drop down. Honestly things look and feel great, I'd just really like to nail it down before I get it tuned. I'll have to see what my tuner thinks as well. Thanks for all your guys' help, I really appreciate it.
 

·
Registered
Joined
·
161 Posts
Discussion Starter · #16 ·
So... with a wideband I can now really see what harm a boost leak can have. Under good amounts of boost(10- 15 psi) I'll see ithe AFR dip to about 11.5, and when take my foot off the gas at about 4k rpms, I'll shoot up to 20.0(the highest it will go). This means that a lot of air is escaping under boost, and also that a huge amount of unmetered air is coming in when under heavy vacuum. This is obviously terrifically frustrating. The only thing I can think of is that it could be that my passenger side tgv gasket is blown out. Either the manifold to tgv, or tgv to engine. The noise sounded like it was coming out of the turbo inlet hose, but I've capped everything off in that area, so it leads me to believe that it's at the bottom of the intake manifold... I want to test soon, and since I don't have a vape or anything to make smoke, I might be picking up a cheap cigar tonight.. To me it seems easier than other methods, and I don't really know where to pick up dry ice.

I'm not sure what it's possible to tune to, but I think it's likely that the previous owner set the wastegate to activate after 20+ psi. I live about 3 miles off pavement in the country, so I can really hammer down to see if I have fixed anything when doing these tests. Every time I get closer to stopping most leaks, but I'm finding that my boost keeps spiking higher and higher. It makes me a little worried, but right after I find this leak and fix it, I'm getting tuned.

Thinking back, if I would've known it had these issues(anyone who knows anything about boost would've been able to tell), I would've looked for a different car. I hate myself for being so naive at that point, and it just sucks that this was the car I chose to buy. I haven't seen anyone having these extensive leak issues right off the bat.. I've put a ton of time into the car trying to get it to run the way it should've when I bought it. It's so damn frustrating.
 
1 - 16 of 16 Posts
Top