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2011 STI Hatch, Plasma Blue, Cobb stage 3
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Discussion Starter · #1 ·
Hi everyone!

I haven't posted much on here but have spent some time reading on different subjects. I need some help with my build......encountering an issue that no one locally (shops and protuner) can solve....just getting shrugs.

In March this year, I decided to further build my STI with the what I believe to be a 'reasonable' power output of 330 WHP (about 400 crank as I have noticed most stock subies dyno about 70 HP less to the wheels). For some reason, even after all the mods and cash I have into this car, it won't push past 270 WHP and even there, it doesn't like it.

The build details:
2011 STI Wagon, base option model car
I bought the car in Aug 2019 used at 60,000 miles with a fresh engine done 5k miles earlier in Jan 2019. Spun a rod bearing according to previous owner. New engine came with:
  • IAG Stg 1 block with forged pistons, "thicker OEM" conrods, nitrided crank. Vex Performance in Calgary AB then put on their built in house 'performance' heads. Probably just a refresh of the valve train really.
  • Killer B pickup tube with larger pan, baffled
  • Exedy Stage 1 race clutch
  • New timing belt with Tomei billet guide
  • New oil pump
  • AEM air intake
  • COBB turbo outlet and intercooler hoses
  • COBB turbo inlet from airbox
  • retained factory top mount IC
  • Air pump delete
  • TGVs removed/ported
  • Radium AOS
  • Grimmspeed downpipe
  • Accessport of course

Car was broken in on the dyno at that time and made a respectable 275 WHP. The tuner paired up with VEX in Calgary (AirBoy tuning).....sees tons of these cars per month. A stock STI on his Dyno Dynamics unit on 91 octane makes about 230 WHP. I drove it like this 1.5 years to get used to the car, all was well.

Fast forward to March this year. Car at 85,000 miles. Now has everything above PLUS:
  • Replaced the 'nameless' axle back exhaust (obnoxious) with new COBB system connected to the Grimmspeed downpipe (already larger diameter, still in good shape, no cat)
  • COBB TD05-20G turbo (i know there are better models out there but this was a reasonable price for my modest build)
  • AEM air intake replaced with COBB SF w/ air box......the ID of the tube is larger than AEM.
  • COBB fuel system upgrade kit (AEM 340 in tank, all lines and rails under the hood, ID 1050X injectors)
  • COBB fuel pressure sensor
  • COBB boost control solenoid
  • 1 step colder NGK iridium spark plugs

Brought the car back to Calgary to AirBoy tuning and he proceeded to check for boost leaks/smoke test, all good...... BUT made only the same 275 WHP @ 18 psi boost. Symptom was above 15 psi boost it just wouldn't make the proportional power increase (maybe 15 hp more) with additional boost/fuel and would just start to knock so he backed off. Good fuel pressure at steady 45 PSI differential. No misfires. Boost responding dead on to inputs. Smooth idle and lower power demand operation. Upon review of the engine bay, he noticed I was running an Rock Auto purchased MAF sensor. My OEM had died the year earlier....temp sensor went wonky.....reading way higher than ambient outside. Why did I do this? Cause it was a lot cheaper than one from the dealership. We chalked this up to potential issue with the MAF and perhaps a bad load of fuel. I went home unhappy. AirBoy also noticed that my ID1050X injectors had the wavesprings fully compressed....looked like a pancake stack of washers and wrong to him compared to other cars he sees. He suspected improper spacers used/supplied by COBB causing them to sit further up inside the fuel rail.

I then replaced that MAF with a $390 MAF new one from the dealership. Also made a few other small tweaks that AirBoy recommended like removing the rock screen/mesh I put in my intercooler scoop on the hood to keep rocks/bugs out since his testing shows it impacts air flow and cooling. I called COBB on the injectors and they said as long as they're not leaking the spacer setup is fine.

Tested a couple different fuel suppliers over the summer to establish norms on quality ---- watched my Feedback knock, Fine Knock Learn, DAM like a hawk and locked in my favorite of Shell 91 close to my work in Edmonton, AB.

Just over a week ago I went back down to AirBoy with a fresh load of 91 fuel and was excited to get my tune dialed in. Strapped it on the dyno and got.......you guessed it.....275 WHP @ 18 psi boost. Same symptoms. More fuel applied at 17-18 psi boost starts knocking. Grrrrrrrrrrrrr!!!

Decided to take Airboy's advice, and this week I:
  • ripped the whole intake out, intercooler, fuel rails, injectors. Re-reading COBB's instructions they say my rail spacers should measure 0.625" = 5/8". Mine are only 1/2"......explains the wavespring crunch.
  • brought my 1050x injectors to a local flow/bench tester. He did the full suite of tests and cleaning on them....inspected and replaced the inlet filters (weren't bad though). His as-received test showed a flow of ~950 CC/min.....but all 4 about the same. I had hoped I had a weak one. After a few cleaning cycles, he got them all to about 1000 CC/min. All were within 0.5% of each other. 1/2 hour leak check had no dripping.
  • reconfirmed routing of all fuel lines compared to COBB instructions, looks good.
  • Compression tested my cylinders.....got (in psi) Cyl 1 = 122, Cyl 2 = 119, Cyl 3 = 126, Cyl 4 = 120 ----- generally OK.
  • Checked gapping on my 1 step colder iridiums: all were about 0.029" with cyl 2 being 0.034". I squeezed that one down to 0.029" to match the others
  • Pulled my intercooler y--pipe off to make sure no rag/paper towel from build work was left in.....there was not. Decided to acetone flush and then soapy water flush the whole intercooler just in case. Looking down through my removed/deleted TGVs, i can clearly see nothing stuck down in the intake runners to the valves....all clear.
  • With the intake off, I'm going to get some additional bungs added/tapped for future gauge expansion since its out of the car now.

So in summary, the only things I have found wrong are:
1) COBB sent the wrong spacers in their fuel rail kit, so injectors sit farther into the rail. I can't really see this causing the issue but I will remedy to make sure
2) the one spark plug was about 0.034". Could be it but no misfiring detected. Maybe the 1 step colder are the issue?

At this point, the car is still apart in my garage after the above work. I'm pulling my hair out trying to figure out what could be wrong. Any takers? If you read all this I'm impressed.....thanks for your attention! ;) I welcome any thoughts no matter how small they might seem.
 

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I assume Sunny logged the WGDC? Did he have any comments?

My fully built 2011 with +1MM valves, s2 cams, FMIC, and 94+Meth made 343whp / 425 wtq on a rotated GTX2863 with a .63 A/R housing on their dyno. This turbo is slightly smaller than yours, but might have newer aero technology.

If you are seeing knock you could add meth injection, or go with toluene in the fuel, or boostane. Could load it up with race gas and see if its phantom knock. AFD sells SL99 at the pump for like $2.75/L
 

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2011 STI Hatch, Plasma Blue, Cobb stage 3
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Discussion Starter · #3 ·
Thanks for the response! He did check the wastegate duty and didn’t have any comment about it. I could press him a little further on the issue. The next time I head down it will be with a full load of Petro 94 at the minimum. Forgive my ignorance….AFD?
 

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Discussion Starter · #5 ·
Oh, Sunny also said to check to see if the knock sensor is a bit loose. I’ll check the torque on it. Has anyone seen these go “bad” for any reason? I know I’m reaching here. Maybe I should just replace it to make me feel better ;)
 

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Thanks for the response! He did check the wastegate duty and didn’t have any comment about it. I could press him a little further on the issue. The next time I head down it will be with a full load of Petro 94 at the minimum. Forgive my ignorance….AFD?
AFD Petroleum. Local fuel supplier
Address: 1444 78 Ave NW, Edmonton

You just drive into the lot and go in the side door, lady will send someone out to pump SL99 for you (highest unleaded they sell) then you just go back and pay. Or they'll fill a jug if you want. Mightn't hurt to cut your 91/94 with a little 99 to see if your knock is an octane issue.
 

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Discussion Starter · #7 ·
Ah, thanks Alistairh.....that's quite close to my work actually! Nice! 99 octane!!!

YamahaSHO, what file extension does this site accept? It won't take the CSV file I have from the last log I took. It was after putting in the OEM MAF sensor. Up till that point, and to a small degree with the new sensor.....I can detect a 'chugging' sensation under heavy throttle...say from 3000-5000 RPM. Then it seemed to smoothen out. At it's worst it could be seen a few cycle per second variation in the MAF flow reading. I put in a chart below to show what i mean. Like I said, the new MAF smoothened that out quite a bit, but still detectable.

Rectangle Slope Plot Font Parallel
 

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Discussion Starter · #12 ·
Thanks Alistair, I’ll do that tonight when I get back home. Jason kindly looked at my log and noted that the timing didn’t seem very advanced (13 deg at WOT near 6000 rpm) and should be closer to 15-18. I believe Sunny left it this way (safer) since he was detecting knock. Jason reminded me that these forged pistons make more noise in the base case so the knock sensor should have its sensitivity adjusted to see if the knock is real.
 

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Yeah, good advice. You can also throw a ton of octane at it to see if its real knock or not.
Also I think I now remember reading that Sunny did some testing and Petro 94 isn't as good, or is as good as shell 91? I dunno. You might want to ask him what his opinions are on ideal gas in this province.
To get ~95 octane you'd need ~28L each of 91 and 99 which would just about fill a STi fuel tank from empty.

You could put some 99 in, enough to raise the octane several points, email sunny and ask for a tune that has a bit more timing in it, then log and see what happens. I think that might give you your answer.
 

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SWP 2012 GR Hatch
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Yeah, good advice. You can also throw a ton of octane at it to see if its real knock or not.
Also I think I now remember reading that Sunny did some testing and Petro 94 isn't as good, or is as good as shell 91? I dunno. You might want to ask him what his opinions are on ideal gas in this province.
To get ~95 octane you'd need ~28L each of 91 and 99 which would just about fill a STi fuel tank from empty.

You could put some 99 in, enough to raise the octane several points, email sunny and ask for a tune that has a bit more timing in it, then log and see what happens. I think that might give you your answer.
Just a comment on the gas;
I run Petro 94 exclusively.
Car has pretty well run 94 all it's life, I have a 3" stack of receipts to prove it.
When I picked up my Accessport, I installed the Stage 1 ACN tune and monitored a couple tanks of Shell 91 gas just to test.
I was going on long cruises from Toronto>MTL often at the time, so lots of miles quickly.
I had a few instances of higher FNL or FBK while on cruise at highway speed, some north of 3, so I opted to switch back to the Petro 94.
Haven't encountered the issue since, even on the same drive.
While the Shell 91 is 'no ethanol', which is good to some degree, it still doesn't have the knock resistance of the Petro 94 in my experience.
Neither gas knocked at full-throttle, but the Shell wasn't as good at partial throttle or cruise.
 

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2011 STI Hatch, Plasma Blue, Cobb stage 3
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Discussion Starter · #15 ·
Thanks for the feedback on the fuel quality and different octanes. Austin, I have found similar results with fuel in Edmonton on my car. Shell 91 will knock (sometimes FBK, sometimes FKL) at part throttle. In the 90F summer temps it would pull 3 degrees. Maybe one out of 6 or 8 hard pulls would exhibit some WOT knock (1.4 - 2.8) as well. Once putting in Petro 94, almost all of that subsides. Maybe once in 25 miles/40km it will show part throttle knock while moving from say 15% throttle to 25% throttle. 0.7 to 1.4. Rarely any timing pull at 100%.
 

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Discussion Starter · #16 ·
Just had another thought. Before I took this car to Sunny for tuning after the build this spring, I thought I would let a local shop take a swing at the tuning instead of driving the 3 hrs each way to Calgary. Guy claimed to have tuned a lot of them with success. Wasn’t the case. Whatever he did caused it to run very rich on the dyno….dropping below 9. Black smoke coming out. He did about 1/2 dozen pulls like that then gave up. My new spark plugs were sooty enough that I replaced them. Any chance this might have plugged up/screwed up the cat? Perhaps it’s restricting exhaust flow? Seems that could result in less power output and perhaps knock from back pressure/heat?
 

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I wouldn't think the cat would be plugged by that.

Send me you full mod list in an e-mail. I'll send you a map to run a couple low load logs on and see if I see anything. It's just easier for me that way.
 

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Discussion Starter · #18 ·
Well, small update…looks like this will take some time yet. Hogged out my cat (now hollow) and spent several hours reassembling the engine and started it for the first time after a month. Got cylinder 4 misfire code and running rough.
Set the accessport to watch cylinder roughness on all cylinders…only #4 is acting up….continually cycling up to 99. Tried twice after resetting codes.
Figured maybe my ******* spark plug gapping method (bench vice ;) screwed up the plug so i swapped with cylinder 2 and tried again. No change. Still cyl 4.
Then figured maybe the coil pack stopped working for whatever reason. Swapped it out with cyl 2 and tried again. Same problem.
Then thought perhaps I plugged in cyl 4 fuel injector backwards (polarity). Online reading told me solenoids shouldn’t make a difference. But when I took the connectors apart again, I saw they can only go together one way.
Ran the engine with cyl 4 injector unplugged so I could check voltage across the pins on wire harness side….get 10.9-11V but that is on a straight DC setting on my multimeter and I know it is probably struggling to interpret pulses. I just wanted to ensure a line hadn’t gotten torn and just reading zero.
Tightened the ‘pins’ in the connectors to ensure a tighter fit and reclipped back together. Ran again, no change.
I was sure nothing was left in the intake manifold (rags) when I reassembled. Any ideas before I rip this fuel system apart again? Perhaps when I break the lines and fuel sprays out I might just toss a match and walk away!
 

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Discussion Starter · #19 ·
Alright, just in case this helps someone else (I haven’t tried yet….Will tonight) I phoned the guy who flow tested my injectors 3 weeks ago and he said there is a chance it is ‘stuck’/seized. Claims he’s seen it happen on a number of 1050x series injectors. He recommended ‘lightly’ rapping on it with a plastic/rubber mallet via screw driver or similar to give it enough shock/vibration that the solenoid gets unstuck and starts working again. Wish me luck!!
 

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If you had one seized injector, you should be able to see it on plugs and logs. Cylinder roughness and knock "noise" should be pretty apparent.

Can't say I've seen any ID1050's have this issue before.
 
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