Cosworth Supercharger Owners Thread

[Cosworth_0686]

Originally Posted by gtengr

Have you tried pushing the elbow further onto throttle body? That should bring the pipe closer into alignment with the bracket.

I just went out and checked, and the end of the elbow is fully in contact with the throttle body; it can't go down any further. Also, I tried to see how many pieces of paper I could slide between the cold air pipe and the intake runner for cylinder 3(?), and it turned out that I couldn't even fit a single piece of paper down between them. It's down as far as it'll go, and there's no wiggle available.

[sly]

Not really Cosworth related but I put a catch can on the WRX today as well. We'll see how well these things work...

I checked the BRZ today. I've driven it with the can attached for about 100 miles so far. There is a little oil already collecting in the can. Not much, maybe a few drops. But it's enough to be able to swirl it around. So yes, the BRZ does have some blowby with the supercharger.

[Cosworth_0686]

Originally Posted by sly

The spacer pushes out on the GDI box so that it doesn't hit the injectors. As for the intake tube, are you sure you have your 90 elbow on correctly? My Cosworth logo is facing back towards the firewall but yours is facing toward the front. It's pretty difficult to get that bolt in. Mine's just slightly too high as well. I had to press down pretty hard on the intake tube to get the bolt to line up. If you push the intake tube back a little away from the mounting tab, you can get it to go down a little to get the bolt started.

I'll loosen up the side bolts a bit and try to push down to see if I can get it to budge. As for the COSWORTH lettering, my elbow has it on the front and back.

[sly]

Yes, remove the other bolts. You want to attach the top bolt first. Don't tighten it down until you get the others started. Once you have the top bolt and the two on the side started, then you can tighten them up all the way.

[gtengr]

Originally Posted by sly

Not really Cosworth related but I put a catch can on the WRX today as well. We'll see how well these things work...

I checked the BRZ today. I've driven it with the can attached for about 100 miles so far. There is a little oil already collecting in the can. Not much, maybe a few drops. But it's enough to be able to swirl it around. So yes, the BRZ does have some blowby with the supercharger.

Yep, I pulled the MAP sensor today, and it had a bit of oil residue on it. I plan to install a catch can tomorrow. Wish I'd done that from the start.

I'm still working on P0172 too. Cleaning the MAF no longer fixes it. I'm hoping I find a vacuum leak when I go to install the catch can, though I always thought an intake leak would result in a lean condition not rich. I'm also confused at how unplugging and cleaning the MAF initially fixed the issue and now it doesn't.

[sly]

Originally Posted by gtengr

Yep, I pulled the MAP sensor today, and it had a bit of oil residue on it. I plan to install a catch can tomorrow. Wish I'd done that from the start.

I'm still working on P0172 too. Cleaning the MAF no longer fixes it. I'm hoping I find a vacuum leak when I go to install the catch can, though I always thought an intake leak would result in a lean condition not rich. I'm also confused at how unplugging and cleaning the MAF initially fixed the issue and now it doesn't.

You still running the stock filter? I know that the Cosworth NEEDS more intake air flow than stock. I would get a high flow filter in first before doing any significant troubleshooting. You know that the filter is bad so I would recommend starting there first.

[gtengr]

Originally Posted by sly

You still running the stock filter? I know that the Cosworth NEEDS more intake air flow than stock. I would get a high flow filter in first before doing any significant troubleshooting. You know that the filter is bad so I would recommend starting there first.

Yes, stock air filter, but I don't think it's an issue. The surface area that Subaru lists for the stock +2017 air filter is sufficient to support this power level (a free flowing filter should make more power, but the car should have acceptable idling and low speed driveability with the stock filter).

The strangest thing about it all is that the initial ~400 miles were completely trouble free. Then it starts bogging a few days later, I unplug the MAF and clean it, that fixes it for a few miles, and then the rich/rough running comes back, and now MAF cleaning doesn't seem to help it. I'm going to take a better look at everything tomorrow when I install the catch can.

[Cosworth_0686]

Originally Posted by sly

Yes, remove the other bolts. You want to attach the top bolt first. Don't tighten it down until you get the others started. Once you have the top bolt and the two on the side started, then you can tighten them up all the way.

I put in the top first(loosely), then worked the front one in a little and managed to force the middle one in on its own, as the threads wouldn't even reach the intake runner with the gdi box and the spacer in place. With the top bolt in place the end of the pipe lines up with the air box much better, but the mounting flange on the side is quite separated from the intake runner. With the top bolt out, things bolt together nicely. With it in, nothing really wants to line up easily; it's like the jig that held things together while fabricating the part was messed up.

[gtengr]

I think I used just one of the side bolts along with the top bolt due to similar alignment issues. I'll confirm tomorrow.

[mrg666]

Originally Posted by gtengr

Yes, stock air filter, but I don't think it's an issue. The surface area that Subaru lists for the stock +2017 air filter is sufficient to support this power level (a free flowing filter should make more power, but the car should have acceptable idling and low speed driveability with the stock filter).

The strangest thing about it all is that the initial ~400 miles were completely trouble free. Then it starts bogging a few days later, I unplug the MAF and clean it, that fixes it for a few miles, and then the rich/rough running comes back, and now MAF cleaning doesn't seem to help it. I'm going to take a better look at everything tomorrow when I install the catch can.

P0172 generally means that there is less air going to the intake manifold than what MAF is reporting which causes more than ideal mix of gas injected. MAF is most probably reporting air flow right but there should be an air leak after that. You need to chase the hoses and clamp the leaking connections. I had four locations and the o-ring gasket of MAF itself. The solenoid under the intake manifold has two unclamped hoses connected to it. I had to clamp both ends of those two hoses. Just like you said, there was no problem initially but those hoses came completely loose after driving a while with FI. Also, I would make sure MAF is mounted flush with a tight seal.

Check MAF reading with an OBD-II device before and after. I had idle MAF reading of 3.4-3.5 g/s before fixing the air leaks. After fixing, MAF reading went down to 2.8-2.9 g/s.

[sly]

Originally Posted by gtengr

The strangest thing about it all is that the initial ~400 miles were completely trouble free. Then it starts bogging a few days later, I unplug the MAF and clean it, that fixes it for a few miles, and then the rich/rough running comes back, and now MAF cleaning doesn't seem to help it. I'm going to take a better look at everything tomorrow when I install the catch can.

Be sure to check your air cleaner for overtightness. Step 1 is to see if your cat has any answers. Together we determined that the problem was the hose clamp was too tight and it had deformed the air cleaner box. If you overtighten the clamp, it will deform the plastic and you will get a leak. I took a plastic funnel and a heat gun and warmed my air filter box and pressed the funnel down into the opening to round it back out. Then be sure to reattach the clamp just so it's snug but not tight.

[gtengr]

Originally Posted by mrg666

P0172 generally means that there is less air going to the intake manifold than what MAF is reporting which causes more than ideal mix of gas injected. MAF is most probably reporting air flow right but there should be an air leak after that. You need to chase the hoses and clamp the leaking connections. I had four locations and the o-ring gasket of MAF itself. The solenoid under the intake manifold has two unclamped hoses connected to it. I had to clamp both ends of those two hoses. Just like you said, there was no problem initially but those hoses came completely loose after driving a while with FI. Also, I would make sure MAF is mounted flush with a tight seal.

Check MAF reading with an OBD-II device before and after. I had idle MAF reading of 3.4-3.5 g/s before fixing the air leaks. After fixing, MAF reading went down to 2.8-2.9 g/s.

Thanks for your input. I went through a few packs of clamps during the install and made sure to clamp every connection to the blower on both hose ends. Doesn't mean something didn't tear or get pinched though. I should have time to tear into it tonight or tomorrow to confirm.

My MAF logs from when it idled acceptably was ~4.3 - 4.4 g/s. That was with a raised ~920 rpm idle.

Originally Posted by sly

Be sure to check your air cleaner for overtightness. Step 1 is to see if your cat has any answers. Together we determined that the problem was the hose clamp was too tight and it had deformed the air cleaner box. If you overtighten the clamp, it will deform the plastic and you will get a leak. I took a plastic funnel and a heat gun and warmed my air filter box and pressed the funnel down into the opening to round it back out. Then be sure to reattach the clamp just so it's snug but not tight.

Thanks for the pics! I tried to feel for that, but didn't realize the deformation is that mild, so I'm not sure I would have been able to detect it by feel under a hose. Seems a likely cause as this would explain the slow onset of the issue, and my thinking that cleaning the MAF was fixing something may have just been me shifting this connection a tad during the MAF removal/re-install.

[BoostTheBrz]

Originally Posted by Cosworth_0686

What did you get? I've got a 2017 and ran into the same issue.


Also, upon fitting the cold air pipe, it seems that it won't line up with the mounting point at the back of the IC core. There doesn't seem to be any room to push it down for the hole to line up, as it'd hit the intake runners. The short end of the 90° is connected down at the throttle body. Could this fastener have been welded on too high?
The GDI driver box also seems to be twisted out away from the engine at the top end by the supplied spacer (20045323); it still bolts up, but seems to be under more stress than it really should be. Any thoughts?

Hello!


I got this coupler: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


And this filter: https://www.ft86speedfactory.com/bli...17-brz-86.html


Both have been working great. I did have to fanagle with the intake tube quite a bit to get the holes to line up, even then I can't get the spacer to fit with the longer hex bolt. I found out my cooling issue was a bad charge cooler, I'll have to post those pictures soon.

[gtengr]

Here is the list I'm working through right now, any thoughts or additions?

1. Remove airbox, check for warped connection to hose coupler. Replace coupler with better fitting part. Cosworth coupler seems about an inch too short for solid fit between stock +2017 airbox and Cosworth intake tube.

2. Remove intake pipe.

3. Check/replace crankcase line. I had to add a splice here on original install, I'm going to remove the splice and use a single hose.

4. Add catch can to PVC line.

5. Check torque on main supercharger bolts to head.

6. Re-install everything. Idle test.

7. If idle test fails, replace brake booster line even though it's clamped on each end and appears fine.

My research suggests 3/8" line from PCV to can, then 1/2" line from can to throttle body. Anyone know the line size on the crankcase line? I haven't found that in my search yet and want to make sure everything is on hand before I continue.