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Old 02-27-2013, 08:46 PM   #1
forester06x
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Default 2006 Forester ECU Tuning with Eaton M62

Hi all:

First off, the "N/A with Bolt-On FI" forum doesn't get much hits so I've posted it here, mods feel free to move.

This summer up in Minnesota, I'm doing a 5MT swap and a custom supercharger project with a short-snout Eaton M62 and FMIC. I am doing this because, 1) My car has severe hail damage and won't resell for a 5MT car with the same mileage, 2) I want the low end torque and sexy whine of a supercharger, and 3) I just want to learn and get experience with grassroots tuning and working on Subarus. So my project is justified in this case.

I've got a couple questions regarding MAF sensors, intake routing, TB relocation, BPVs, and ECU tuning on my EJ253 that is soon to receive 5 psi of intercooled boost. 5 psi on premium should be plenty safe enough.

Here is my proposed intake tract setup:

Air filter--> MAF--> recirc lines from BPV + breather hoses--> supercharger--> FMIC--> BPV--> throttle body--> intake manifold and all that follows.

1. The ECU is programmed with how long it takes air flowing past the MAF sensor to reach the valves. When you move the MAF sensor around the intake tract or extend the tract, like with an FMIC kit, the MAF becomes "laggy" and throttle tip-in becomes SUPER rich to the point of smoking and stumbling. I've heard this is un-tuneable. With my proposed intake tract setup above, will I have a severe problem with this? Or is it impossible to tell until we start tuning the car?

2. With my proposed intake tract setup, the throttle body is AFTER the supercharger. Wat? Yes, it's possible, but in this situation a BPV is critical- unlike turbos that will just get compressor surge, a supercharger can't relieve pressure backwards if there is no pressure release as from a BPV or BOV. (I will use BPV because MAF sensor). Some say that 5+ psi of boost running through the very small BPV valve still puts a strain on the supercharger. What say ye? (this relates to question 3 as well)


Keeping the TB after the supercharger is easy because there's no TB relocation involved, but the negatives are:

-Really loud (as long as it's not a cop magnet I don't care)

-No boost control- it's either at full boost or no boost. The CBV is open with the vacuum at idle, and stays open and relieves pressure (read: PSSHHHH) until enough pressure from the supercharger slams it shut. So when the CBV does slam shut, boost goes suddenly rushing into the engine and power hits like a freight train. Cool and surprising for passengers , but inaccurate power delivery and certainly no fun for RallyX or AutoX.

3. Some say the pressure from the supercharger is too much for the BPV, and they say that I would need two BPVs and run them in parallel. What say ye? Do I need an extra BPV at only 5 psi?

4. Is it hard/worth it to relocate my throttle body BEFORE the supercharger like normal supercharged setups?

5. If I relocated my throttle body to BEFORE the supercharger, apparently because 5 psi is relatively low, that I would NOT need a BPV. What say ye?

If I relocated the TB to BEFORE the supercharger, it would look like this:

Filter--> MAF--> breather lines--> throttle body--> supercharger--> FMIC--> intake manifold.

6. If I relocated the throttle body, do you think I would have problems with the MAF being too far away from the intake manifold? Or you just can't tell until you get it tuned?

And the final questions:

7. I'm looking at NF Performance to possibly tune my car, as it's relatively close to where I'm working in Minneapolis MN and they've built some monster Subarus. Do you think they would be willing to tune my custom setup? On a second thought, I guess I should PM them about that.

8. How much would a one-off custom tune such as this cost? I'm guessing anywhere from $50-$100 per hour...


Wow, that was a long post.
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Old 02-28-2013, 12:16 AM   #2
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That is a long post and to many questions sorry but I don't feel like writing one too. Sounds like a good project though.
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Old 02-28-2013, 09:23 AM   #3
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After some more research, I'm leaning towards putting the throttle body before the supercharger is best. Only 5 psi risks no engine damage so I don't need a BPV to mess with. I still might have problems with MAF lag and tip-in, so I'd like some help with that.
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Old 02-28-2013, 10:00 PM   #4
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Bump.
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Old 03-01-2013, 02:05 PM   #5
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Check the turbo/built motor forum. Many people have added FMIC and tuned successfully. The obvious solution seems to be to move the MAF sensor so that it keeps the ecu happy. Seems like relocating the MAF housing or getting a aftermarket housing and tuning the MAFv scaling would be the method.
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Old 03-01-2013, 08:01 PM   #6
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Thanks. Hadn't thought about an aftermarket MAF housing, I had just assumed I was going to re-use the stock housing to save money. I don't think I could put the MAF after the supercharger because the MAF can't measure pressure and adjust fuel tables accordingly? Or is there a MAP sensor somewhere in the EJ253 that I haven't heard of?
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Old 03-01-2013, 08:49 PM   #7
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Quote:
Originally Posted by forester06x View Post
Thanks. Hadn't thought about an aftermarket MAF housing, I had just assumed I was going to re-use the stock housing to save money. I don't think I could put the MAF after the supercharger because the MAF can't measure pressure and adjust fuel tables accordingly? Or is there a MAP sensor somewhere in the EJ253 that I haven't heard of?
There is a MAP sensor on the 253 and I think it is located just after the TB but I cannot confirm. Tuning for positive relative manifold pressure is also something that had already been done with a 253 AFAIK. Check out www.romraider.com forums, openecu.org for info on tuning and lots of documentation from the developers of the tuning software. The discussion is intelligent and very informative if you have a good idea of how a modern EFI system works.
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Old 03-02-2013, 03:10 PM   #8
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I am going to have it professionally tuned, probably by NF Performance up in St. Paul. I'm willing to do a lot of risky things with my car, but tuning is not one of them. I will go ahead and check out the tuning for manifold pressure, that sounds pretty interesting. I wonder if the MAP sensor on the EJ253 is even sensitive all the way up to 5-6 psi considering it's not meant to be boosted.
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Old 03-02-2013, 04:44 PM   #9
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Quote:
Originally Posted by forester06x View Post
I am going to have it professionally tuned, probably by NF Performance up in St. Paul. I'm willing to do a lot of risky things with my car, but tuning is not one of them. I will go ahead and check out the tuning for manifold pressure, that sounds pretty interesting. I wonder if the MAP sensor on the EJ253 is even sensitive all the way up to 5-6 psi considering it's not meant to be boosted.
Many "professional" tuners use open-source tuning like romraider or openecu because it provides access to tuning parameters and tables that other subaru tuning systems do not. I'd also lets you customize table resolution. It offers development and support by the people that wrote the software, develop the programs, etc. I'm not a open-source fan boy but for someone who has an idea of what they are doing, it's the best way to go.
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Old 03-02-2013, 07:22 PM   #10
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Yeah, open source tuning is what I meant by professionally tuned. I think they probably will use Romraider because the 05+ ECUs are can bus and can be tuned that way. Do you have an idea of what it would cost per hour for a tune? How long do you think it would take to tune it, or is there just no way to tell especially with my unique setup? I would be willing to bet that they don't have any base 2006 Forester 2.5X AT maps. They would have to change the idle maps because of the AT--> 5MT swap as well, but that's a simple fix.

I'd love to learn how to tune myself through Romraider and the Tactrix 2.0 box, but I don't have the time to learn/practice, and if I screw something up the consequences are huge. For a high school junior like me, blown engine basically = no car until I get out of college.

I'm pretty much decided on relocating the throttle body to be in front of the supercharger now. Any other opinions? Thanks.
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Old 03-02-2013, 09:09 PM   #11
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Quote:
Originally Posted by forester06x View Post
Yeah, open source tuning is what I meant by professionally tuned. I think they probably will use Romraider because the 05+ ECUs are can bus and can be tuned that way. Do you have an idea of what it would cost per hour for a tune? How long do you think it would take to tune it, or is there just no way to tell especially with my unique setup? I would be willing to bet that they don't have any base 2006 Forester 2.5X AT maps. They would have to change the idle maps because of the AT--> 5MT swap as well, but that's a simple fix.

I'd love to learn how to tune myself through Romraider and the Tactrix 2.0 box, but I don't have the time to learn/practice, and if I screw something up the consequences are huge. For a high school junior like me, blown engine basically = no car until I get out of college.

I'm pretty much decided on relocating the throttle body to be in front of the supercharger now. Any other opinions? Thanks.
I couldn't guess what a tune would cost for this type of setup. One local tuner that does mostly turbo subaru/Mitsubishi stuff said he would tune my ej253 for $200 flat rate until it was perfect if I paid for dyno time at half the dyno shop rate. That was 3+ years ago. And for a unique setup I would think it would be much more difficult to iron it out.

There have been others that have converted n/a ej engines to supercharged. I think I read about one or more that used the supercharger from Mercedes CLK Kompressor's. Try the search tool, you should find some results and at the least be able to pm the author of the thread about what they learned. I think the forums at rom raider would also be fruitful.
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Old 03-02-2013, 10:49 PM   #12
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The supercharger I am using is the same one, an Eaton M62 short-snout from the CLK230. I've read just about all those threads, but tuning on 90% of them doesn't apply at all for me because I have the MAF sensor and DBW. A guy did an M90 build on his 06 Impreza 2.5i and also custom Romraider tuned it. I think our maps would be dang similar, except his supercharger is much bigger and has a different volumetric efficiency map so that would be factored in. He is running an FMIC as well and had big problems with the MAF sensor lag mentioned in my OP, which is why I created this thread. I will do some poking around the Romraider forums and maybe post a similar thread at RS25 as well.

Come to think of it, I highly doubt that the maps from the M90 build would have anything to do with mine, as I am running an M62 at only 5 psi, whereas his M90 was running 6-7 psi. It looks like I'm back to square one with the Romraider forums. I have an old PC that would be sick as an onboard tuning computer.....
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Old 03-06-2013, 04:18 PM   #13
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Well I ordered the supercharger. If I go with the throttle body in front of the supercharger, would I not need to run a BPV? I'm only going to run 5-6 psi.
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Old 03-06-2013, 04:21 PM   #14
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You're going to need a bypass valve for a roots blower to function correctly and allow you to actually run in vacuum.

if not, tuning should be easy because you'll have 5-6psi all of the time. maybe even boost at idle.



edit: BPV on supercharger is opposite of a turbo car. You're bypassing at idle and when you don't want boost. Keep the bypass contained with the blower or close to it.

Should have turbo'd it.
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Old 03-06-2013, 06:35 PM   #15
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At idle wouldn't the supercharger just be sucking air through the IACV because the throttle plate is closed?
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Old 03-08-2013, 09:54 AM   #16
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No IACV on a DBW subaru...

Quote:
Originally Posted by forester06x View Post
At idle wouldn't the supercharger just be sucking air through the IACV because the throttle plate is closed?
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Old 03-08-2013, 11:50 AM   #17
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I wondered about that. So at idle is the throttle plate just barely cracked open then? I wasn't able to observe that when doing the SeaFoam treatment with the intake tract removed. At idle the supercharger would be "boosting in vacuum" because it would be trying to suck a bunch of air through the cracked open throttle plate. So would a CBV be necessary with the throttle body in front of the supercharger?
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Old 03-16-2013, 09:59 AM   #18
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Bump for the question above. ^^^ Pics of the FMIC test fitted on my custom steel lower bumper beam. Nothing's bolted in because I mis-drilled two holes.



So you can see the MAF sensor will be much farther away from the intake manifold with the FMIC piping than it was with the stock intake.
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