2018 BRZ FA24 Swap

[MX-5RACER]

I completed an FA24 swap into my newly acquired 2018 BRZ. When cool, it will run normally and rev freely. I drove it around the block and it held load, but as the car warms up, it will not rev past a certain point. It will stop at 4k, then 3k and then when fully warmed up it will not rev past 2k. I hooked up my scan tool and watching live data, I can see it logging misfires on every cylinder.


When first fired up I was getting a P000D code, which I was able to resolve with swapping the OCV on the exhaust cam on the driver's side and the code has not come back. The tune is the factory FA20 tune.


The car came with an OFT, and I confirmed it is on the factory tune. I did a datalog, but I cannot for the life of me figure out where it is saving it when I export it.

[MX-5RACER]

I am still having issues with this car and it is driving me crazy.

Some of the things I have tested:
Swapped MAP sensor from the FA24 to the FA20
Installed a new MAF sensor
I verified that the throttle plate is matching the throttle pedal command when hot and cold.
I verified no vacuum leaks with a smoke machine, injected at 10psi.

I was getting an issue only when hot, and only when trying to rev above 2k rpms. I took the intake manifold off yesterday to check the wiring changes and connections. When I reassembled and restarted, I experienced the issues much sooner than previously and now it does not want to idle hot. I seemed to have made it worse, which may be a good thing. I plan to pull the intake manifold this evening and redo the crank sensor wiring. I just want to double check and try to eliminate it as an issue.

Anyone else have any suggestions?

[RT-BRZ]

The symptoms you listed (not revving past 2k rpm) sounds like the car is in limp mode. If you are using an OFT, search for any faults/CELs that haven't triggered the dash light. Limp mode occurs when the ECU is protecting the engine due to something being wrong. I haven't done your swap but I've read that you have to change things like the reluctor wheel(s) and other hardware. I also believe the OEM tune will run that engine properly. I'm not an expert on this but no one else has responded.

Also, if you don't have a tuner, get one.

[MX-5RACER]

My car is a 2018, and on the 2017+ up cars, there are minimal changes that need to be made. You need to change or adapt the following sensor plugs: Crank sensor, Coolant Temp, Evap solenoid and the oil temp. sensor. You also need to move the FA20 fuel pressure sensor over to the FA24. I sometimes get a P0300 code for multiple/random misfire.

I have been trying to figure out my issue. So far, I have swapped coil packs and spark plugs, I changed out the MAF, changed out the MAP sensor, cleaned and redid all the grounds, and replaced the DI Controller. Nothing so far has corrected my issue. I did get a hold of a 2018 service manual, and I have been going through the diagnostic procedure for P0300. One of the tests was to check the resistance between the two pins on the high-pressure fuel pump. My pump is showing higher resistance than the specification for the 2022+ FA24 pump. Spec is 0.45 - 0.55 ohms from what I can find online, which is the same for the FA20. My pump is reading 1.0 ohm. I am trying to source a new pump. If anyone has one they can test to confirm what a functioning pump should be, that would be awesome.

[Lynxis]

To run the OEM ECU and tune, you also need to either modify the existing cam reluctor wheels, or change them with modified ones from RS motors. I see you didn't mention this, so I'm guessing this is your problem.

Alternatively, you can use the existing fa24 wheels and position censor if you run the Link ECU and get a tune, but the combined cost of this is roughly twice as much as the RS motors kit.

[MX-5RACER]

Originally Posted by Lynxis

To run the OEM ECU and tune, you also need to either modify the existing cam reluctor wheels, or change them with modified ones from RS motors. I see you didn't mention this, so I'm guessing this is your problem.

Alternatively, you can use the existing fa24 wheels and position censor if you run the Link ECU and get a tune, but the combined cost of this is roughly twice as much as the RS motors kit.

I appreciate the response. I am not sure you are correct about the cam pick ups as my car is a 2018. From what I have read on the forum and on the links on Hachi Electronics site, the 2017+ cars already use the same cam pick wheels as the FA24.

I have a question for the people who have completed this swap and still running on the factory tune (or at least ran it for a short time before getting a tune), what intake manifold and throttle body did you use?

I am currently running the FA24 intake manifold and throttle body. My current thoughts are the direct injectors could be clogged and do not operate correctly when warm. I am going to pull the direct injectors and have them cleaned and flow tested as I am hoping to find a smoking gun. I am also thinking about putting the 2018 intake manifold and throttle body on the car before I pull the direct injectors.

[MX-5RACER]

The saga continues. I have purchased an OBD2 cable and Techstream software and have been trying to run through the diagnostic process laid out in the service manual for P0300. Part of that process is to use the Techstream Active Test to control the Injection mode. The problem I am having is my fuel system is staying in NG (No Good) status and not OK status which is NFG (No F&CKING Good) for me. One of the conditions is the EVAP test has to be completed prior to allowing the fuel system to go into OK status to initialize the test. The EVAP test is performed between 1/4 and 3/4 of a tank of fuel, as mentioned above my car was filled with fresh 93.

I will have to drain some fuel or see if the Techstream software can force the EVAP test to complete.

Going by some live data, I was able to really heat soak the motor at idle and it started running rough and eventually died. During this time, I was monitoring the low pressure fuel pump with an install gauge and the HPFP data in Techstream. I am seeing correct low pressure fuel numbers (fluctuating at idle between 40 and 60 psi, with a steady 58psi with throttle applied), however the HPFP data is showing the HPF oscillating a bit from 700 down to 240-ish when being commanded to 580.

I am going to try and fit another HPFP and see what happens.

[MX-5RACER]

Ok, I was able to resolve my issue. Long story short, don‘t be cheap like me; buy the Hatchi Electronics wire harness adaptors. I decided to use the FA24 harness that came with my engine and cut and splice the connectors on to my original FA20 harness. I made another mistake and decided, against my better judgement, to use the heat shrink solder tubes, instead of my usual ”Western Union Splice” with shrink tubing. I must have had a cold solder joint on one or multiple wires I had spliced using the heat shrink solder tubes. Clipping them off and soldering them the correct way has resolved my issues!

Now I have some minor issues to correct. I have to figure out what I am going to do about the gauge cluster hood as the vinyl cover has shrunk and has peeled off the back. I also have to replace the alternator as the diode in the voltage regulator is toast and is putting 12 volts out of the field wire. The is also an issue with the A/C. The compressor clutch is engaging, so there is ”Freon” in it, but probably not enough.

I picked up a GR86 steering wheel, and I dyed the stitching red, as my wheel was toast from sun damage from sitting in the S. FL sun for a year when the car was parked. I will be installing that at some point this week.

[RT-BRZ]

Originally Posted by MX-5RACER

Ok, I was able to resolve my issue. Long story short....

Congrats man. I know stuff like that drives you crazy. I'm glad you got it figured out.

[MX-5RACER]

Time for an update:
My engine did not come with the FA24 exhaust manifold, so I had to reuse the FA20 exhaust manifold. After some internet research, it seems the FA20 exhaust manifold is a potential restriction. I sourced a used, low mileage, FA24 exhaust manifold and swapped it over. This will cause me headaches shortly.

I had some minor teething issues like having to put a little bit of R134a into the A/C to get it to blow cold, but I am driving the car around. I have been working with a tuner getting some revisions to the tune. My car came with an Open Flash Tablet and as I said before, I am cheap, so I have been trying to stick to using it.

I was not a fan of the wheels that came on the car so after some Facebook Marketplace deals I was able to score a set of 17x9 RPF1's, in gold, with RT660's for $360 (After selling the 18" wheels that came on the car).

Baby got new shoes!


The car came with a Tomei titanium single exit exhaust and while the tone is nice, ITS TOO DAMN LOUD! I have acquired an HKS HiPower V2 exhaust and through some Ebay searching I was able to score what I think is a Gruppe-S overpipe. After some cleanup on the overpipe, I wrapped it with DEI exhaust wrap and installed it and the HKS exhaust.


Now for those of you playing along with the home game, you may already know the issue I will have. For those of you who do not know, the flange on the FA24 exhaust manifold to the overpipe is at a slightly different angle than the one on the FA20 exhaust manifold. This causes the larger overpipe to contact the subframe. I have loosened everything and realigned it, loosened and realigned, loosened and realigned, still no joy. Last night I gave up and went to the autoparts store and bought the widest grade 8 washer I could and jacked the motor up and put the washer on the passenger side engine mount, tilting the entire engine 2-3mm. So far there is no more contact on the subframe and I like the HKS exhaust, but it is a bit too quiet now... picky, I know.

Things still left to do:
Get this thing to a dyno.
Change the oil and filter again.
Drop the oil pan and check for RTV in the pick-up (Not sure about this one).
Look for a front pipe to potentially unlock more HP?
Sell the Tomei exhaust and the FA20 Red intake manifold.

[Joon525]

I ran into the same situation with my FA24 swap.
I have the MA Performance header which is designed around the FA24 which has the header flange/overpipe flange rotated.
I only found out about the difference when I tried to bolt up the Gen 1 overpipe I had.

So to repeat the issue for anyone else, if you are swapping the FA24 and using a header designed for the Gen 2, you should also be using a Gen 2 overpipe.

If you use a Gen 1 header, use a Gen 1 overpipe.

[Teseo]

Check the a/c compressor. Sometimes those o-rings get toasted and leak from there. Very common when they age