K swap FRS : Freddy McShreddy part deux

Do you feel that there are any handling changes due to what I'm guessing is a higher C.O.G.  going from a boxer to an inline? Big thumbs up for getting this done and documenting the work!

In reply to flat4_5spd :

Boxers tend to sit rather high up in the chassis compared to an inline because the crankshaft necessarily has to be in the middle of the engine, and there has to be room underneath for the exhaust.

It is sort of the same deal as with rotaries, kinda.  What little gains you might get with the engine get lost with how high up the trans has to be and stuff.  Look at an Impreza for example, the crank centerline is almost as high as the top of the bumper.  And there is no place for accessories but the top of the engine.

The overall package is flatter but it is also higher up, so it tends to be a wash.  The big advantage other Subarus have vs. transverse AWD is the engine is the only thing in front of the front axle, the heavy-ass transmission is behind it.  With a transverse arrangement, the engine AND trans are in front of the axle. Usually pushed forward of it enough that the axles point to the back of the car.

In reply to flat4_5spd :

Honestly it's hard to say as of yet. The chassis right now wants to understeer more than my previous setup but there's too many variables to blame it on the swap. Throttle will correct that real quick like though.

I will say this is my favorite version of the FRS/BRZ I've driven yet. It feels less wheezy down low, eager to rev, and the K swap most of all doesn't seem out of place. It feels like it's how it should have been from the factory. I would like to drive another modded fa20 on the same day to see if my bias towards where my wallet went isn't a thing. Hopefully I can get a couple track days and plenty of autocross next season to find out.

750 mile check in. Gas level gauge is still wonky. Right about 11 gallons into the tank the gauge jumped from just a hair above half to empty with the light illuminated. Nothing in between. That leaves 2 more gallons to get where I need to fill up, so about 40ish miles which is okay. Not exactly how I would prefer things to be but for now until the bug is fixed I shouldn't be running out of gas. I've been watching the trip meter between fills like a hawk and probably should carry around a 5 gallon emergency jerry can just in case.

I've been battling with this low speed/RPM jerkiness when hovering just under 2k or slightly above 2k RPM to sustain speed through and around my neighborhood though. On highway or on throttle the car drives great. But if there's just a hair of throttle backing out or in that's feather light things just get annoying. I live in a slightly hilly, curvy, low speed neighborhood and this is where it just makes me want to floor it or just roll around with it out of gear. So I've been tinkering with the Decel settings in Haltech but the problem remains no matter what values I adjust. So last night I shut Decel off below 30 mph. It drove glorious. But I need to run about 40 in one section and it started being a real jerk again. So I switched Decel off completely to make sure it was responsible for my woes. And just like that we are smooth as butter on minimal throttle in or out regardless of speed. Clearly there is some tweaking needed in the Decel but what I've tried may have barely lessened it. I'm looking for a remote tuner to start working on my tune but probably won't begin that journey until after the holidays.

Vibration I think is related to the trans tunnel clearance and not driveshaft. I think. I spent some time sustaining the RPM that vibration is most prevalent, and when I place my hand near where the trans could touch on the passenger tunnel carpet, it's the source of it. Moving my hand around I can pinpoint it exactly. I can touch the driver side tunnel and while there is some vibration the source appears to be passenger side where the clearance was tight. Going to investigate further when I change the oil in a month or so. Probably pull the whole enchilada and do some trans tunnel bashing.

I also rolled through somewhat of a milestone with the car. I purchased it with 99531 and rolled over 100k about 250 miles ago.

Sounds like the TPS threshold for fuel cut is set too high. I think you mentioned reducing the threshold previously but it would appear you're still running into light throttle situations that's triggering it. I would think you wouldn't want fuel cut to kick in unless TPS was under 1% or something. That being said the Elite has some awesome decel fuel cut settings. I've generally avoiding using it in my RX7 because I have an older Platinum Series ECU and the only criteria for fuel cut is TPS. If I recall correctly the Elite can consider TPS, RPM, vehicle speed, engine speed, A/C on/off setting and more.

infernosg said:

Sounds like the TPS threshold for fuel cut is set too high. I think you mentioned reducing the threshold previously but it would appear you're still running into light throttle situations that's triggering it. I would think you wouldn't want fuel cut to kick in unless TPS was under 1% or something. That being said the Elite has some awesome decel fuel cut settings. I've generally avoiding using it in my RX7 because I have an older Platinum Series ECU and the only criteria for fuel cut is TPS. If I recall correctly the Elite can consider TPS, RPM, vehicle speed, engine speed, A/C on/off setting and more.

It started out at 1% and I think I made it worse moving it to 3%. I could move it to 1/2 a percent and see? I'll give that try and report back.

So you have to basically tune this thing yourself with no support?

In reply to infernosg :

Looks like .5% fixed it!

In reply to docwyte :

Sort of. The base map gets you going but yes for optimal performance it needs tuned. Honestly the base tune isn't that bad but my throttle appears to be more sensitive causing a little kerfluffle. 

In reply to captainawesome :

That's awesome! 0.5% seems low to me but it's all dependent on the throttle setup. Maybe DBW has more fidelity than cable throttles, which is what I'm used to but I rarely find myself using <3% throttle while driving. Regardless, all that matters is you're able to smoothly drive around at low speed and decel fuel cut still triggers when it's supposed to. The only other advice I have would be to verify how TPS is being used since DBW uses both pedal and actual throttle position and they usually aren't 1:1 aside from at 0% and 100%. I'd assume the ECU would use the actual throttle position but I don't know for sure. I haven't played with DBW stuff enough but it's something I'm eventually looking to get into when I install my Elite 1500 next year.

In reply to infernosg :

Throttle position gets a little wonky if you are used to cable throttle, because there is no set "home" position and idle control through a separate valve.  It is all throttle plate all the time.  Deceleration fuel cutoff should only happen low enough when you are engine braking anyway, so we're talking super low throttle position at low RPM, especially with a small engine and huge throttle.

In reply to captainawesome :

So is there a shop locally that can tune the car for you on the dyno?  Is the stand alone really common and not hard to find a knowledgeable tuner?

In reply to docwyte :

Looking at a couple places to get my tune remotely and then a dyno session at a local buddy's shop with the same tuner. Tuned by Shawn knows the Haltech platform and Hondas so he's at the top of my list. Also Humble Performance out of Tulsa but I'm not sure they are interested in street tunes more than race and that's not what I'm looking for. I could be wrong. I've read some poor customer service reviews from them but zero from Tuned by Shawn so far. I'd rather pay for experience and depth of knowledge on this than save a few bucks trying to get a bargain bin tune.

Drivability is annoying because you spend 99% of your time there, but it also takes 99% of the time to calibrate well.  A lot of tuners focus on making a dyno hero for the main fuel and spark tables, and sort of phone it in for the rest of everything.

This is a lot of why people suggest starting with the OE computer if at all possible.  (Obvs. not possible for you if you want the gauges to work)  The annoying "everything else" is already mostly calibrated well.  That's all stuff that is going to have to be calibrated from the ground up with a standalone.

A tuner who is willing to work with you to get the drivability nailed, and I mean everything from cold start on up, is worth their price.  It might take a few iterations to get there.  It's also a good opportunity, if you are so inclined, to build a new skill.  Certainly you would have a strong incentive to get the calibration as well-honed as your standards are.

That's why I've always tried to stay with the stock ECU whenever I can.  The OEM's have spent a ton of time making sure that the car will start/idle/run in all sorts of situations.  I don't want to have to try and recreate that myself with a standalone...

Looks like I spoke too soon on the jerky throttle. Before I carry on trying to fix the problem I need to run some logs and see what exactly is happening when the throttle buck/jitter pops up. Until then I could be chucking medicine at symptoms that don't exist.

With the long holiday weekend I avoided car stuff for a few days. My wife insisted I go to the garage yesterday to get out of her hair. So I went down a short list of stuff and tried to knock a few out.

Last week I was reading that the CSG Tein Flex A can be a little understeery/pushy with the MY13-16 rear sway bar. This confirms what I've already experienced, so I wanted to see what the least intrusive option would be without stiffening everything up and creating a less compliant ride. Stock rear sway on mine is 14mm but in 2017 all of the twins switched to 16mm. This is a good way to neutralize handling but not suffer daily drivability. So I found one shipped for $65 on ebay and it just so happened to show up Sunday morning. Haven't got a chance to see how much it has effected any hard cornering but it should do the trick from what I've read.

While I had the car in the air I decided to look and see what my trans clearance looks like. I was hoping this was the smoking gun to my vibration but it's not touching and shows no sign of touching under load. It doesn't look like a two piece driveshaft is possible utilizing the stock carrier bearing bolt locations, and I'm not interested in any hackery solution to move it rearward. For now I'm just going to deal with the vibes and maybe sometime in January I'll pull everything and see if I'm mistaken. For sure I'll make more room in the trans tunnel, and also track down the weeping coolant at the coolant neck on the rear of the head.

A week or two ago I had cleaned and re-greased all of the caliper sliding pins. I noticed the rubber bushings on the lower front calipers were missing so I ordered some new ones to replace them all. I decided to do the rear along with the front since they were cheap, but also because they were a little swollen when I put them back in. I think someone used a grease that isn't compatible with rubber and with it being a little larger will cause some binding of the pins. Didn't take long to get them all done but it felt good to wrap up that little project. Going to order some new soft lines soon. The stock ones look fine, but I'd like to put fresh ones on before I get on a track as well as a more aggressive pad compound for street/autocross. I've got some Carbotechs for the rear when I go to track, but still need to find a deal on some fronts and a new set of Centric blanks for just those pads.

I also ordered up a DRL kit for the Winjet headlight buckets. The LED strip that runs across the face of the headlight is only on under DRL and switches off as soon as the headlights are on. Either in high or low beams, so the cheapie ebay kit solves that issue. Now I have a tiny bit of added light at night and it just looks cooler.

When I set up all of the flex fuel sensor stuff I was still waiting on the 8 pin connector I had ordered to plug into the stock harness. Kpower had sent me the info on where the wires needed to go, so I got to pinning. It was easy as pie to get it all put together and looks factoryish. I haven't configured the sensor in the Haltech yet, but hopefully it's all as it should be. Just a matter of swapping the upsized injectors and a tune when it's time to add the corn juice now.

Do you have stock injectors in the K24? Wideband? Curious what your injector duty cycle and AFR look like when it's bucking during light throttle.

In reply to obsolete :

Stock injectors currently. Hopefully I can get a few logs tomorrow and see what's what. If not I'll switch decel off until I get a chance to tinker.

Captain awesome,

Thanks for sharing your build with us.

I can't get this setup out of my head. I have passed over the twins a few times specifically because of the subaru engine. I love the honda K engines. The age of both donors is ideal. 

What are you doing for stability control and ABS?

Will your stand alone ECM interact with the ABS for traction control? Will ABS act independently of whatever the engine is doing?

Thanks again for sharing.

In reply to daytonaer :

To my knowledge and understanding the stock ABS and TSC still are working like factory as that's all talking nicely to the Haltech through CAN protocols.
 

I'm so far really happy with the swap. I can't say it's been financially an intelligent decision but I'm having fun with cars so can't complain too much.

If working on cars was an intelligent financial decision, I think this forum would be full of rich people. Sadly, that's not the case.

Great work on the swap so far. 

Welp. I went to Cabo with the family for New Years and came back with Covid. While in quarantine I might as well tinker a little so that's what I did today.

Before I left town I had tried out my new camber gauge which was showing over -3 degrees camber in the rear. This sucks because I don't want to raise the car any and the SPC camber arms I had before were a nightmare to set camber AND toe. They also used eccentrics which ruined two pairs of tires from letting loose on two different occasions. It just so happened that a buddy of mine decided to back out of k swapping his FRS and had some fancy SPL lower control arms and Verus toe arms. They were a few hundred under MSRP and brandy new so I paid the man. Today I installed them. Nice, pretty, lighter, and best of all lovely adjustment that doesn't let loose. I'm now at -2.5 degrees in the rear where I like things to be.

The Verus toe arms also have something cool worth mentioning. They have a spacer to drop the arm back to parallel for lowered cars. Restores geometry close to where stock would be which I "think" allows less aggressive toe curve with suspension travel?

Was hoping my corner marker lights were going to show up today but they never did. Maybe tomorrow. Probably spend some time placing felt in spots to reduce some interior rattles.

How'd you get back home if you have covid?  I was in Cabo too, needed to take a test 24 hours before my flight home 

In reply to docwyte :

Took test day before and was negative along with the family. Had symptoms of sinus crap that next day when we got home. I tested the next day to be sure and there it was. Whole family has been vaccinated and even the wife has had a booster. Kids still haven't shown any signs, just me and the wife. Luckily it's all been mild and manageable. So I guess I'm assuming I got it in Cabo?

Sounds it.  Glad you're not feeling too badly...