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Old 03-16-2021, 10:06 AM   #251
stevieturbo
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I really cannot imagine it is surge, although I would agree to get rid of the MAF.
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Old 03-16-2021, 12:25 PM   #252
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Quote:
Originally Posted by WRXXXED View Post
I haven't read through this thread too much but why not use a speed density kit so you don't have to worry about maxing out the maf?

The MAF is sort of a secondary issue I just haven't gotten around to addressing yet. There is really not much support for speed density on a NA ECU. Either the open source version (MerpMod) or commercial (DimeMod), I'm not getting much help. I am sure someone has done it...


at the moment, I am leaning towards a calibrated MAF sensor where (in theory) I just drop it in and set the MAF ecu values to known airflow numbers and it should be pretty close right out of the box , which would save a bunch of work scaling and they are good for like 700g/s in a 2.75" ID tube if I am reading right. I do enjoy closed loop fueling since I do drive the car everyday in all weather , it is nice to not worry about cruise fueling.

Here is the calibated MAF sensor I have been eyeing.

https://www.pmas-maf.com/product/hpx...cement-engine/
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Old 03-16-2021, 12:50 PM   #253
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And what do they mean by calibrated ?

They actually offer data for your specific ecu/software ? and mode of install ?

Why not just go to a standalone ecu ?

Or why not just stick your MAF in a larger tube if you are maxing it out ?
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Old 03-16-2021, 01:49 PM   #254
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Yeah PMAS supplies airflow in g/s for 0-5v based on the tube size. Not sure how much fine tuning would be required, I am sure some. The sensor itself has a different resolution too. For example to get 700g/s @4.7v out of a factory Denso MAF, you would need a very large diameter pipe I am sure.

Standalone is a possibility, really not sure what is out there for NA cars.

For a larger tube, by the time I buy a new fat tube and filter, and tune it, I'm willing to pay a little more for the calibration and smaller form factor.
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Old 03-16-2021, 03:19 PM   #255
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Quote:
Originally Posted by pcampbell View Post
Yeah PMAS supplies airflow in g/s for 0-5v based on the tube size. Not sure how much fine tuning would be required, I am sure some. The sensor itself has a different resolution too. For example to get 700g/s @4.7v out of a factory Denso MAF, you would need a very large diameter pipe I am sure.

Standalone is a possibility, really not sure what is out there for NA cars.

For a larger tube, by the time I buy a new fat tube and filter, and tune it, I'm willing to pay a little more for the calibration and smaller form factor.
It really wouldn't take a small increase in tube diameter to have a large effect.

And whether the engine is turbo or n/a is irrelevant for an ecu. Use the ecu as you wish.
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Old 03-16-2021, 07:32 PM   #256
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Problem seemed to be gone today, tested about 4x pulls, it is about 40F out vs 15F yesterday, so if it is surge, it's right on the edge.
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Old 03-24-2021, 12:11 PM   #257
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Could anyone confirm that their turbo evap purge valve/solenoid does not leak boost - just pull the intake manifold side vac line coming off of it and use a hand vac to pressurize it a bit? Looks like my NA version leaks badly back to the fuel tank. It holds vacuum just fine. Seems less than ideal. It seems like a turbo solenoid will drop right in, same connector and bolt pattern etc.

Last edited by pcampbell; 03-24-2021 at 12:26 PM.
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Old 03-24-2021, 01:36 PM   #258
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Let the tank vent to atmos via the charcoal can, or into the airbox or something.

Normally the evap solenoid will only operate under light loads etc...but it's a fair question as to whether n/a or boosted operate slightly differently.

Can't say I've ever tested, and only really ever work on boosted cars.

Unpowered I would expect the solenoid to be closed though. You could monitor behaviour of power to the solenoid under various driving conditions.
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Old 03-24-2021, 07:10 PM   #259
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I am trying to follow the diagram on the turbo purge system and it looks like sort of like the turbo PCV, where it has an escape route through the intake (pre turbo) when the system is pressurized and otherwise can go directly to the intake manifold. I could be wrong on that.

But yeah just disconnecting and capping for right now seems like the easiest way to fix. I thought originally the turbo version of this solenoid would be fine with no other mods, but that wouldn't let the fuel tank vent when the car is boosting.... which is of course how it is now with the solenoid allowing boost pressure backwards through the solenoid.

Last edited by pcampbell; 03-24-2021 at 07:21 PM.
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Old 03-24-2021, 07:14 PM   #260
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It's not a case of the solenoid, more the control strategies.

n/a might allow tank venting at higher throttle openings or loads.

On a turbo car you could not do that as boost would then feed back into the tank. It could only allow air to pass at low loads, where there is vacuum or near to atmospheric in the intake as pretty sure it normally goes to the intake manifold on a turbo car.
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Old 04-19-2021, 07:32 PM   #261
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Well I was doing some dumb stuff , trying to dial in the fueling a bit with the water meth disabled and blew #4 . I did have race gas in the tank, but leaned out enough to , I assume break the ringland. Engine is out but I have not opened up the motor yet. But, after much debating on how to rebuilt the motor without breaking the bank decided to go with with an STi rod + Manley forged piston combo.

-New setup will not be anything too crazy different but slightly lower CR ~9:1.
-Moroso oil pickup
-Stiffer valve springs
-SOHC ARP studs
-Minor but switching the water meth lines to SS ... noticed the stupid plastic stuff was leaking at the quick disconnect fttings.

-IAG SS power steering hose because the stock formed hose has really been the way of the supercharger.

-Oil pump, may add 1 shim to bring the bypass above 70psi, not sure if I need it for revving to ~7400rpm....
-May throw an 06+ WRX clutch and flywheel in there

Other stuff to be decided, welcome suggestions that won't leave me broke

gratuitous messy engine bay pic (engine cradle and rack and pinion out for cleaning and replacement parts)

Last edited by pcampbell; 04-19-2021 at 08:11 PM.
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Old 04-20-2021, 01:02 PM   #262
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Push fit fittings are convenient, but they do suck.

Do proper teflon lines and screwed fittings. I wouldnt go to the hassle of full stainless hardline though.
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Old 04-24-2021, 08:32 PM   #263
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Pistons look pretty good to me for 210,000. Bottom one is the one where I suspect to find a broken ring land. Wonder if the water meth cleans them????
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Old 04-25-2021, 04:21 AM   #264
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water of any kind in the chamber will clean pistons ( and chamber ) over time.
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Old 04-25-2021, 04:06 PM   #265
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The old hotrodders trick was to trickle water through the carb into a warm running engine to remove carbon deposits. The water can boil quickly enough when hitting a hot surface to physically remove the carbon by blowing it off the piston dome.
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Old 05-05-2021, 12:40 PM   #266
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So I actually decided to put my spare stock ej259 motor in. Was feeling a bit not sure about the rebuilt shortblock and for almost $2k, I have some other ideas for the future for not much more.

I wanted to pull the #4 piston to make sure it was cracked since I couldn't tell anything from the top. the bore itself is really unscathed. Just a couple little cracks on the piston.





Just waiting on my heads from the machine shop right now to put it back together.
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Old 05-05-2021, 01:18 PM   #267
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You caught it early before the piston got a lot worse.

They break soo easy from a little detonation.
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Old 06-24-2021, 05:56 PM   #268
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Any ideas on this?


On a WOT pull the left side bank leans out starting around 6k, to a peak lean condition at 6400 before richening again to expected AFR.

Note these are the factory AFR sensors that bolt right up to the head. The only thing I can think of is that I have UELs.. The driver side is much shorter. But I don't really see how that could make it do this. And why would it go lean, then back to normal.

Factory fuel rail
Factory FPR
Fuel injector clinic 750cc injectors
DW 300c fuel pump

I don't think it's a fuel pressure issue , wouldn't that cause both banks to go lean?

Ignore it and just trust thhe rear wideband???

I tried swapping injectors left /right and I tried swapping front AFR sensors left / right separately with no change in behavior.

Last edited by pcampbell; 06-24-2021 at 06:20 PM.
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Old 06-24-2021, 09:23 PM   #269
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Injector compensation table may help.
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Old 06-25-2021, 06:44 AM   #270
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Default Vortech supercharger for ~500whp? Si Too big?

Quote:
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Injector compensation table may help.


Yeah i guess I could tune it out with per injector computer but still can’t figure out why it would happen. Seems very odd to go lean and then back.

Also why the first 2 cylinders in the fuel rail would get less fuel than others... that is if it is legitimate.

Last edited by pcampbell; 06-25-2021 at 06:56 AM.
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Old 06-25-2021, 02:05 PM   #271
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Do I read your table correctly - the Passenger side head AFR is off scale on the low side and you are in the range of 11.5-12.5ish on the Driver side head?

See some posts by TurboQueef where he had a header with bungs installed so he could test the per cylinder AFR's and tune that out. His shared that a tuner had commented that this AFR variation is a real issue with Subarus and why some EJs pop.

I would stay out of significant boost until you figure this out.
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Old 06-26-2021, 08:16 AM   #272
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Default Vortech supercharger for ~500whp? Si Too big?

Right. Usually both factory sides read 11 and wideband (behind and combined) read 10.9-11.x. There is a bit of methanol in the mix so it is not as rich as it sounds.

But the odd thing is that it only happens at a particular range. Only wot and only around 6400rpm although it comes on slow enough that I can see it coming and then Richening again after 6400.

Unfortunately cyl 2/4 exhaust are already combined inside the head. It’s a weird 2 year setup.

So even if I were to guess and do cylinder fueling comp I don’t really know which one is the problem.
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Old 06-26-2021, 04:38 PM   #273
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Good feedback. That driver-side AFR is a conundrum to me unless Subaru has a self-destruct built into the ECU by leaning out one head under boost and WOT.

Just one point - the AFR probes detect oxygen partial pressure (concentration) in the combustion gases and that is correlated back to AFR in the ECU or W/B electronics. In principle, the probe does not care if you are burning gasoline, ethanol, methanol, etc, and unless you configure it differently, will read in terms of a gasoline AFR. So the mixture really is at 11.0, regardless of the presence of methanol injection.
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Old 06-26-2021, 07:08 PM   #274
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Default Vortech supercharger for ~500whp? Si Too big?

Ah yeah I guess I mean that ~10.9:1gasoline and methanol mixture is not as torque robbing as it sounds since peak torque afr for methanol is like 6:1. It’s about 12:1 gasoline and the rest of that comes from methanol.
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Old 10-11-2021, 09:05 AM   #275
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Trying to decide whether to go for NAS Performance billet SOHC cams. They are "high" lift and long duration to the point where they require semi custom pistons with bigger valve reliefs. So it is a pretty big project, requiring a new shortblock (~$3500), ~500 valve springs and ~$850 cams. The goal would be ~500whp around 8000rpm. The Vortech will put out 20-22psi in stock form around 52-55k rpm right up to about 700 crank HP. There are aftermarket billet impellers to bump that up a little and they are not actually very expensive. Any thoughts as to whether this will work?

Unfortunately I haven't dyno'd in current form. Good guess is ~300whp @ 13psi at 45k rpm and 7000rpm engine speed. So it would need to put out a lot more at high rpm but, that is what the cam is designed to do.

https://cdn.shopify.com/s/files/1/07...87759233695377
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